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Brief Report Reduced Negative Priming in Schizotypal Subjects does reflect Reduced Cognitive Inhibition Frances L Watson & Steven P Tipper Published online: 09 Sep 2010.
To cite this article: Frances L Watson & Steven P Tipper (1997) Brief Report Reduced Negative Priming in Schizotypal Subjects does reflect Reduced Cognitive Inhibition, Cognitive Neuropsychiatry, 2:1, 67-80, DOI: 10.1080/135468097396423 To link to this article: http://dx.doi.org/10.1080/135468097396423
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C O G N IT IV E N E U R O P S Y C H IA T R Y , 1 9 9 7 , 2 (1 ), 6 7 ±7 9
B r ie f R e p o r t R e d u c e d N e g a tiv e P r im in g in S c h iz o ty p a l S u b je c ts d o e s r e fle c t R e d u c e d C o g n itiv e In h ib itio n Downloaded by [Adams State University] at 11:05 10 December 2014
F ra nc e s L . W a tso n a n d S te v e n P . T ipp e r S ch o ol o f P sy ch o log y , U n iv ersity of W a le s, B an g o r, U K
N u m e ro u s s tu d ie s h a ve s ug g es te d , v ia th e inter p re ta tio n o f th e ne g a tive p rim ing e f fe c t a s a m ea s ur e o f c og n itiv e in h ib itio n , tha t sc h iz o ty pa l su b je c ts a r e le ss ab le to in hib it irre le v a nt dist ra c tin g inf or m a tion . R ec e n t r es ea r ch h as r ev e ale d, h o w e ve r, th at n e ga tiv e p rim in g e ff ec ts c a n b e ca u se d b y tw o q uite d iff er e nt p ro c es se s: d ist ra cto r in h ib itio n a n d p er c ep tua l r e v ie w . T h e r ef or e , u n e q uivo c a l c o nc lu s io ns c o n ce rn in g le ss e ff ic ien t inh ib ition in s c hizo typ a l in d iv id u a ls a re n o t po s sib le f ro m p r e v io u s re se a r c h . T h e p r e s e n t e x p e r im e n t m in im is e s th e c o n tr ib u t io n o f p e rc e p tu al re v ie w to n e ga tiv e p rim in g a n d d e m o ns trate s th a t w he n a pu r er m ea s ur e o f in h ib itio n is ta k en , s ch iz o ty p al s ub je c ts ar e in d ee d le ss a ble to in h ib it irr e le v an t d istra c tin g st im u li.
IN T R O D U C TIO N A n in a bility to ign o re irre lev a n t stim u li h as be en re g a rde d a s a ce n tra l u nd e rlyin g fe a tu re o f sch izo p hr en ia sinc e th e d iso rd er w as first d e scr ib e d (B le ule r, 19 1 1 / 19 5 0 ): ``T h e sele ctio n w h ic h a tte ntio n e xe rcise s o v er n orm al se n so ry im p re ssio n s m a y b e red u ce d to z ero , so tha t a lm o st ev e ry th in g tha t m e e ts the se n ses is re g iste red .’ ’ L a te r, M cG h ie an d C h a p m a n (1 9 61 ) p ro po se d ``a b rea k d ow n in th is selec tive -inh ib ito ry fu nc tion o f a tte ntio n ’ ’ th a t lea d s to an o v e r-in clu sio n o f irre le v an t in form atio n an d th e n , to se c on d a ry d istu rba n ce s in pe rc ep tio n a n d th o u g ht. F rith (19 7 9 ) h a s a lso p ro po se d a ``d e fe c t in th e m ec h an ism tha t lim its a n d co n trols th e c o n te n ts o f c o n scio u sne ss’ ’ as the ba sis fo r the po sitiv e sy m p to m s (h a llu c in a tio n s, d e lu sio ns, th o u g ht d iso rd er) o f sch izo p hr en ia.
R e q u e s ts fo r re p ri n t s s h o u ld b e se n t t o D r F ra n c e s W a t so n o r P ro fe s s o r S t ev e n T ip p e r, S c h o o l o f P s y c h o l o g y , U W B , B a n g o r, G w y n e d d L L 5 7 2 D G , U K . T h is r es e a rc h w a s s u p p o r te d b y th e H ig h e r E d u c a tio n F u n d in g C o u n c il fo r W a le s . W e ar e g ra te fu l to D r M . J ac k s o n a n d P ro fe s so r J .M .G . W ill ia m s fo r a c c e s s t o t h e i r s u b je c t s a m p l e , a n d to B r u c e W e a v e r fo r te c h n ic a l s u p p o rt.
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1 9 9 7 P s y c h o l o g y P re s s , a n im p ri n t o f E rlb a u m (U K ) T a y lo r & F ra n c is L t d
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S u ch in hib itio n-b a sed th eo ries o f sch izo p h ren ia a re su p p orte d b y ex p e rim en tal ev id en c e; p eo p le w ith sch iz op h ren ia p e rform po o rly o n ta sks th at d em a n d the sele ction o f re lev a nt in fo rm a tio n fro m a n irre lev a n t b ac k gr ou n d , c om p a re d to he a lth y c o n tro ls. F u rth e rm o re, h e althy in div idu a ls w h o re p ort p ers on a lity traits th a t rese m b le p sy ch o tic sy m p tom s (sc h izo typ a l p e rso n a lities) a lso p e rfo rm p o orly on the se ta sk s re lative to lo w sc h iz o typ a l in d iv id ua ls. P a tie nts w ith sch izo p h re n ia an d sch izo ty pa l su b jec ts h a ve b e en rep o rte d to sho w re la tiv e d eficits on th e W isc o ns in C ard S o rtin g T e st (B raff et a l., 1 9 91 ; L en z en w e g er & K o rfin e, 1 9 94 ), laten t in hib itio n (B aru c h, H em sley , & G ra y , 1 9 88 a ,b ; D e la C a sa , R u iz, & L ub o w , 1 9 9 3), th e in h ib ition of in ap p ro p ria te m ea n in g s o f a m b ig uo u s w o rd s (B u llen & H em sley , 1 9 8 4; C h a p m a n , C ha p m a n , & M ille r, 1 9 64 ), c ro ss-m o da l set sw itc h in g (S prin g, 1 98 0 ; W ilk in s & V e n a ble s, 1 9 92 ), sim p le re ac tio n tim e (R T ) p rep a rato ry in terv a l cro ss-o v er (R o sen b au m , S h o re , & C h a pin , 1 9 8 8), a nd v ig ila n ce (C P T ) (C o rn b latt, L en z en w e g er, & E rle n m e y er-K im lin g , 1 9 89 ; L e nz e n w e g er, C o rnb latt, & P u tn ick , 1 9 9 2; O bio ls, G a rc ia -D o m in g o , de T rin ch e ria , & D o m e ne c h , 1 9 9 3 ). T h ese rep o rte d p a rallels s u g g e s t th a t sc h iz o ty p a l su b je c ts e x p re s s t h e sa m e fo r m o f a tte n tio n a l in e ffic ie n c y a s p a tie n t s w ith s c h iz o p h r e n ia , a n d th a t sc h iz o ty p a l g r o u p d iffe re nc e s in sele ctive a tte n tio n p rov id e a m o d e l fo r a tte ntio n al d e fic its in sc hiz o p hre n ia . S u ch fin d ing s p ro v ide stro n g su p po rt fo r th e d im e n sio n a l h yp o th esis o f p sy ch o sis (e .g . C larid ge , 1 9 8 5, 1 9 8 7). T h is p ro p os es th a t a n u n d erly in g c on tin uo u s p re disp o sitio n to d e v elo p sch izo p h ren ia ex ists w ith in th e h ea lth y p o pu la tio n a nd th a t the p re disp o sitio n h as bio log ic al, p erso n ality , a nd co g nitive m an ifesta tio ns . C la rid g e (1 9 85 ) sug g e sts th at m e asu re s of sch izo ty p y sim u ltan eo u sly re fle ct a h ea lthy in d iv id u al’ s pre disp o sitio n to sc h iz o p hre n ia as w ell a s sp ec ific asp e cts o f th eir p e rs on a lity . T h e rep o rte d p a ra lle ls b e tw e en co g nitive p roc e ssing in sch izo ty pa l p e rson a lities an d p e op le w h o h av e sc h iz o p hre n ia th ere fore p o in t to c om m on m ec h an ism s op e ra tin g in bo th h ea lth y a n d clinic al state s, a n d sug g ests th at e v id e nc e fro m sch izo ty p al ind iv id u als m ay b e u sed a s a m od e l fo r sch izo p h ren ia . F u rth e r e v id e n ce fo r an inh ib ito ry d e fic it in sc h iz o ph re n ia an d in sc hiz oty p al p ers on a litie s h a s c o m e fro m stu d ies of n e g ativ e prim in g, a p a rad igm th at p rov id e s a pa rtic u la rly dire ct m ea su re o f th e ca pa c ity to ign o re a n d inh ib it irre le va n t stim u li (e.g . B e e ch , B a y lis, S m ith so n , & C la rid g e, 1 98 9 a ; B e ec h , P o w e ll, M cW illiam , & C la rid g e , 19 8 9 b; L a p lan te, E v ere tt, & T h o m a s, 19 9 2 ). N e g ative prim in g re fers to th e re lative ly slo w re sp on se s th at are m ad e to re ce n tly ig no re d stim u li. W h en a stim ulu s tha t w a s p rev iou sly irrele va n t a nd ig no re d b e co m e s the ta rg et, resp o n se s to th at ta rg e t h av e b e en fou n d to be slo w e r th an u n p rim ed re sp on se s (N eil, 1 9 7 7; T ip p e r, 1 9 8 5). In a ty p ic al n e g ativ e p rim in g ta sk (e .g . T ip p er, 19 8 5 ), tw o pa rtia lly su p er im po se d p ic ture s a re p res en ted in d iffere n t c o lo u rs. T he su b je c t is instru c te d to n a m e re d p ic tu re s a nd to ign o re gre en p ic tu re s. F o r e x am ple , o n th e in itial prim e tria l, a c ha ir is sh ow n in g ree n an d ig n o re d , a nd a d o g is sh ow n in red an d na m ed . O n th e su b seq u en t
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pro b e tria l, the red ta rg et is th e p re v io u sly ig n ore d d ra w in g of a c h air an d th e gre e n d istra c to r is a ne w dra w in g . U n d e r n o rm al c on d itio n s, it ta ke s lo n g er to na m e the red c ha ir pro b e w h en it h a s be e n ig no re d o n the pre v io u s tria l (ig no re d re p e titio n ) th a n w h e n th e d r aw i n g h a s n o t b e e n se e n b e fo re ( c o n tro l). P ara d ox ica lly , in div idu a ls w ith eithe r sch izo ty pa l p e rs on a litie s (e .g . B e ec h e t al., 1 9 8 9 a) or sch iz op h re nia (e .g . B ee ch e t a l., 19 8 9 b) ten d n ot to sho w the se slo w er re sp o nse s. In h ib ition -b a sed m o de ls o f sele ctive atten tio n (e .g . N e ill, 1 97 7 ; T ip p e r & C ra nsto n , 1 9 8 5) in te rp ret n eg a tiv e prim in g effe cts a s ev id en c e fo r d istra cto r in h ib ition , w h ic h is th ou g h t to fa cilita te th e selec tion a nd p ro c e ssin g o f relev a n t in fo rm a tio n . It is a ssu m e d th a t th e re p rese n tatio n o f a n in hib ited d istra cto r is le ss ac ce ssib le fo r fu rthe r p ro ce ssin g, w h ich resu lts in sig n ific an tly lon g e r re spo n se tim e s if a d istra cto r b ec o m e s th e n e x t ta rge t. T h u s, re du c e d ne g ativ e p rim in g effec ts in sc hiz o ph re n ia an d sch izo ty py h av e b ee n in te rp rete d a s ev id en c e fo r re d u ce d co g n itiv e in hib itio n in the se gro u p s. T his is co n siste n t w ith th e pre d o m ina n t v iew o f atten tio n in sch izo p h ren ia, n am ely , th a t in d iv id ua ls w ith sch izo p h ren ia e x pe rien c e a bre ak d o w n in in h ibito ry c on tro l p ro ce sse s an d a re un a ble to in hib it d istra ctin g in form atio n.
PE R C EP TU AL R EV IE W O R IN H IB IT IO N ? A p ro b lem fo r th e fore g o in g in te rp retatio n is th a t pre v io u sly re p o rte d n eg a tiv e prim in g e ffec ts m ay n o t u n am b ig u o u sly re flec t the in h ibitio n o f distra c tors. It w a s rec en tly rea lise d th at ne g ativ e p rim in g e ffec ts m ig h t a lso reflec t th e m o re c o m p le x p ro c e s sin g th a t c o u ld re su lt fro m th e d is co v e ry o f p er c e p tu a l differe n ce s b e tw e e n the prim e distra c tor an d th e p rob e ta rg e t. K a h n em an , T re ism a n, a nd G ib bs (19 9 2 ) h av e p ro p o se d a p e rce p tu a l re v iew pro ce ss w h ich , by c om p arin g c u rre n t a n d im m e d ia tely pre c ed ing stim u li, w o u ld d isco v e r su c h distrac tor-targ e t d iffe re n ce s. T h e y su gg e st tha t a n au to m a tic rev iew of v e ry re c en t p erc e ptu al e v en ts is a p a rt of p erc e ptu a l p ro ce ssin g th a t is c ritica l fo r th e in teg ra tio n o f su cc e ssiv e p erc e ptu al ev e nts. T h is p roc e ss a cc e sses fe a tu re s o f ob je cts tha t are n o lo n g er in vie w an d lin k s cu rre nt a nd p a st in fo rm a tio n to g e th e r to p rod u c e a c oh e ren t p ic ture o f th e w o rld . O u r ow n rec e n t w o rk on se le c tiv e atten tion (M illik en , T ipp e r, & W ea v er, 1 99 4 ) c le a rly su p p orts th e hy p o the sis th a t p e rce p tu a l re v ie w c an co n trib u te to ne g ativ e p rim ing e ffe c ts in som e circu m stan ce s. F o r e x am p le , if a p ic tur e o f a c ha ir a pp e a rs first in gre e n, a s th e prim e d istra cto r, an d th en in red , as th e p ro b e targ et, the d ela y ed re sp on se to tha t ta rge t m a y re fle c t e ith e r in h ib itio n of th e c ha ir re p rese n ta tio n o r th e re so lu tio n o f th e c o lo u r m ism atc h b etw ee n th e tw o stim u li. T h e attem p t to lin k th e tw o pe rc ep tua l o b je c ts tog e th e r is h in d e re d b y th e m ism a tch in g info rm a tio n . S uc h a n in c re a se in pro c essin g tim e co u ld p ro du c e a n eg a tiv e p rim in g e ffec t th at is en tire ly u n rela te d to inh ib itio n. T h is o bse rv ation ha s a fu nd a m e n ta l im p lic a tio n fo r all stud ie s d esc ribin g ne g ativ e p rim in g effe cts. N eg ativ e prim in g effe cts c an n o lo n ge r b e assu m e d to
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re fle c t, u n eq u ivo c ally , distra c to r in h ib itio n , a nd th e d iffe re nt le ve ls o f n e g ativ e p rim in g ob se rve d in c lin ic a l an d p erso n ality gro u p s m a y in fac t reflec t a re du c ed c ap a c ity to rev iew re c e nt p erc e p tu a l ev e nts, rath er th a n a d efic it in th e ca p ac ity to in h ib it irrele va n t in fo rm a tio n . E x isting ev id en ce fo r the rela tio ns hip be tw ee n sc h izo typ y an d n e g ativ e p rim in g h a s a ll b e en o b ta ine d u sin g e x pe rim e n ta l ta sk s in w h ich in h ib itio n a nd p erc e p tu a l rev iew p ro c esse s ha v e b ee n c on fo u n de d . T h is c o nfo u nd o cc u rs w h en th e ta rge t is v e ry sim ila r (b u t n o t id en tica l) to the p rec e din g distra cto r stim u lus . In ne g ativ e p rim ing m a n ipu lation s o f th e S tro o p c o lo u r in terfe re n ce task , w h e re sc hiz o ty p y d iffe ren c es ha v e be e n rep o rte d (B e e c h e t a l., 1 9 8 9 a; B ee ch & C la rid ge , 1 98 7 ; P e ters, P ick e rin g , & H e m sl ey , 1 99 4 ), th e to -be -n am ed ta rg et c olo u r h u e in th e p ro b e d ispla y h as th e sa m e se m a ntic ide n tity a s the pre ce d ing to -b e -ign o red co lo ur w o rd . A lth o ug h th e ig no red d istra cto r w ord an d th e n am ed c olo u r h u e ta rg e t h av e th e sa m e sem an tic ide n tity, th e p rev io u sly ign o red in fo rm ation , w h ich is re p rese n te d ve rb ally b y a c olo u r n a m e , c an n o t, by d efin itio n , m atch p e rce ptu a lly w ith the v isu al h ue rep re se nta tio n of th e ta rg e t. T he re fore , so m e o f th e in d iv id u al v ariatio n in th e n eg ativ e prim in g elicite d by th is ty pe of task m ay ha v e b ee n attrib u tab le to d iffe ren c e s in th e c a pa c ity to p roc e ss this typ e o f m ism a tc h ra th e r th a n to d iffere nc e s in distra cto r in hib itio n . P erso n a lity differ en ce s in n eg a tiv e prim in g h av e a lso b ee n o b serv e d in e xp e rim e nts w h e re th e p rim e d istra cto r an d th e pro b e targ et a re the sa m e w o rd , b u t a re p re se nte d in d iffe re n t co lo urs a n d/o r in d iffere nt p o sitio ns (B e ec h , M cM an u s, B a y lis, T ipp e r, & A g ar, 1 9 9 1; C la rid g e , C la rk , & B ee ch , 1 9 92 ; T ip p e r & B ay lis, 19 8 7 ; W illia m s, 1 9 9 5). A g a in, th e se m a nip ula tio n s ine v ita bly p rod u c e p erc ep tu al d iffere n ce s b e tw e e n th e p rim e d istra c to r a n d the pro b e ta rg e t w h ic h m e a n th a t all o r som e pa rt of th e rep o rte d n eg a tiv e prim in g e ffe cts c o uld b e th e re su lt o f p e rce p tua l m ism a tch ing ra th e r th an in hib itio n . C on se q u en tly , re d u ce d n eg a tiv e p rim in g in p atie n ts w ith sc hiz op h re nia a nd sc hiz o ty p a l su b jec ts m ay n ot reflec t red u ce d in h ib itio n , b u t in ste a d m ay be d ue to a red u ce d a bility to re vie w rec e nt p e rce p tu a l in p u ts. T his p o ssibility is p artic ula rly relev a n t to on e th e o ry o f sc h iz o p hr en ia (H em sley , 1 9 8 7, 19 9 4 ), w h ic h p ro po se s th a t a pe rc ep tu al in te g ration de ficit m ay u n d erlie som e o f the sy m pto m s tha t pa tie n ts e xp e rie n ce . O u r n e w e x pe rim e n ta l te ch n iq u e s (M illik en e t al., 1 99 4 ; T ipp e r, W ea v er, & M illik en , 19 9 5 ), th at a re d esig n e d to p rev e nt re vie w p roc e sse s c on tribu ting to ne g ativ e p rim ing e ffe cts, w ill re ve a l w h eth er it is a failure o f inh ib ition , rath er th a n pe rce p tua l rev iew , tha t u nd e rlie s red u c ed n eg a tive p rim in g in sc hiz oty p al ind iv idu a ls.
E X PE R IM E N T In div id ua ls w ith h ig h an d lo w sc h iz o ty pa l traits w e re co m p are d u sing a sp atial n eg a tive prim in g ta sk in w h ic h th e y w e re re q uire d to selec t an d lo c a te th e la rge r o f tw o circ le s p re sen ted o n ea ch d isp lay (T ip p e r et a l., 1 99 5 ) (se e F ig . 1 ). A
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Illu s tra ti o n o f th e a rr o w m a rk e rs a n d ex p e rim e n t a l c o n d it io n s . T h e t ar g e t w a s d e fin ed as th e
la rg er o f th e tw o c irc l e s. T h e p rim e ta rg e t w a s a lw a y s s iz e 3 (w ith si z e 2 d i s tra c to r) an d t h e p ro b e ta rg et w a s al w a y s si z e 2 ( w i th s i ze 1 d is tr ac t o r) . O n i g n o re d re p e ti tio n tri a ls , th e p ro b e ta rg e t a p p e ar ed in th e s a m e lo c a t io n a s t h e id e n tic al p r im e d is t ra c t o r. T h e n u m b e rs w e re n o t a c tu a lly p re s e n t e d , t h e y ar e d is p la y e d fo r d e s c rip tiv e p u rp o s e s o n l y .
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n eg a tive prim in g effec t of ±2 6 m illisec o nd s (c on trol 4 58 m se c; ig n o red rep e tition 4 8 4m se c) ha s be e n re po rted fo r y ou n g h e althy v olu nte ers o n this ta sk u sin g the sa m e -size d stim u li (T ip p e r et a l., 19 9 5 ). A s th e p rim e d istra c tor a n d th e p ro be targ e t are id en tic al on ig n ore d rep e titio n trials, th e n eg a tiv e p rim in g o b tain ed is a ssum e d to re flec t th e e xte nt to w h ic h th e distrac to r rep rese n tation h as b e en 1 in hib ite d d u rin g sele c tio n. A sig n ific a nt asso c ia tion b etw ee n sch izo ty py a nd n eg a tive p rim in g w o uld in d ic a te th at sch izo ty p al pe rso na lity tra its are re la ted to th e e xte n t to w h ich d istra c to r in h ib ition is utilise d in sele ctio n. S ch iz o ty p y d iffe re nc e s w e re m e a sure d u sin g the rec en tly d ev e lo pe d O x fo rd ± L iv e rp oo l In v en to ry of F e eling s a nd E xp e rie n c es (O L IF E ), w hic h y ield s fou r r el a tiv e ly in d e p e n d e n t s c h iz o ty p y m e a s u re s fro m a 1 5 9 - ite m s e lf-r e p o rt q u estio nn a ire (M a son , C larid ge , & Jac k so n , 1 9 9 5 ). S u b je c ts w ere se lec ted on th e b a sis of th eir ``U nu su a l E x pe rie n c e’ ’ sc ale sco re w h ic h co n ta in s pe rce p tu a l, h allu cin a to ry , a nd m a gic al thin k ing item s an d is d esc rib e d as ``c on sisten t w ith `p ositiv e’ sy m pto m s of psy c ho sis’ ’ (M a son e t a l., 1 9 9 5). T he U n u su al E xp e rie n c e (U N E X ) sca le w a s u se d b ec a use it w a s th e m o st c lo se ly re late d to C la rid g e’ s S T A (C la ridg e & B rok s, 1 98 4 ) m e asu re in b o th th e O L IF E d ev e lo pm en t sam p le (M a son e t a l., 1 9 9 5) a n d in th e sam p le (N = 2 13 ) from w h ic h th e p re se nt g rou p s w e re rec ru ite d (Ja ck so n , p erso n al c om m u n ica tio n ). T he S T A h as b ee n use d in a lm o st e v ery p rev iou s stu dy in w h ich a n a sso cia tio n be tw e e n sc h iz o ty py a nd n eg a tive p rim in g ha s b e en rep o rte d , an d it a pp e ars to c a ptu re the re lev a nt p ers on a lity in fo rm atio n. G iv e n th at inh ib itio n-b a sed the o rie s o f sc h iz o p hre n ia (e .g . M c G h ie & C h ap m an , 1 96 1 ) link atte n tio n a l de ficits to p ositiv e ra the r th an n eg a tive sy m p to m s, a h ig h ly relate d, b u t m o re sp e cific a lly p ositiv e sy m p to m sc ale w as co n sid e red a pp ro p ria te. E v id en ce fo r o ur a ssu m p tion th at p o sitive sy m pto m sc hiz o ty p y tra its a re the m o st lik e ly to re la te to va ria tion in n e g ativ e p rim in g w a s also re c en tly re po rte d b y W illiam s (19 9 5 ).
M E TH O D S ub jects T w e n ty -n in e sub je cts w ith hig h U n u sua l E x pe rie n ce (U N E X ) sco re s a nd 28 su b jec ts w ith lo w U n u su al E xp e rie nc e sco re s w e re re c ru ited from a su b sa m p le o f 17 6 sub jec ts w h o ha d co m p le te d th e O L IF E a s p art of an o the r un rela ted stu d y. T h e se le c tio n su b je cts w e re 35 ye a rs of ag e o r le ss a n d h ad a L ie sc or e 1
A v a ri et y o f d i ff e re n t ta s k p ro c e d u re s h a v e b e e n in v e s ti g a te d . F o r e x a m p le , i n T i p p e r e t a l.
(1 9 9 5 ), m a rk e rs i n th e d i sp la y p ro v i d e d a b a c k g ro u n d c o n te x t a g a i n s t w h i c h th e s ti m u l i w er e p e rc ei v e d . T h i s b a c k g ro u n d c o n te x t e n su re d th a t t h e i g n o re d p rim e a n d s u b s e q u e n t p ro b e w er e p e rc ei v e d a s th e s a m e s i ze , w h i c h i n c re a s e d t h e p e rc e p t u a l s im i la rit y o f t h e s e s tim u li. W e d id n o t u se s u ch p ro c e d u re s h e re b ec a u s e t h e c o n te x t m a rk e rs c o n s id e ra b ly in c re a s e th e c o m p le x i ty o f th e d is p la y
and
w o u ld re d u c e th e p ro b a b ili ty o f s e v e re ly im p a i re d g ro u p s ( e .g . p a tie n t s w ith
s c h i z o p h r en ia , A lz h e im e r’ s D is e a s e , e tc .) c o m p le t in g th e t as k e a si ly . H o w e v er , t h e p at te rn o f n e g a ti v e p ri m in g ef f ec t s o b ta i n e d u si n g t h e c o n te x t m a rk e rs a re t h e sa m e a s th o se o b ta in e d w ith th e ta s k re p o rte d h e re .
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(E y se nc k & E y se nc k , 1 9 75 ) o f 9 or less. In d ivid u als w ere in v ite d to pa rtic ipa te if th e y w e re am o ng th e 6 0 hig he st U N E X sc o re rs or the 6 0 lo w e st U N E X sco re rs in the sam p le. T h e vo lun te ers w er e stu de n ts an d sta ff at th e U n ive rsity o f W a les, B a n go r. T h ere w e re 9 m ale p artic ipa n ts in ea ch U N E X gro u p . T h e h ig h sco ring sa m p le ha d a m e an U N E X sc o re o f 1 9 .8 (S D = 4 .0 3, ran g e 15 ±2 9) , a m e an a ge o f 2 1.5 ye a rs (S D = 4 .0 ), an d a m ea n L ie sc o re o f 4 .0 (SD = 2.6 ). T h e lo w sco rin g sa m p le ha d a m e a n U N E X sc ore of 2 .9 (S D = 1.7 3 ra ng e 0 ±5 ) a n d a m e an ag e o f 2 2.9 ye a rs (S D = 3 .8 ), a nd a m ea n sco re o f 4.3 (S D = 2 .9 ). A ll su b je c ts h a d n o rm al o r co rrec ted -to-n o rm a l vision a nd n o rm a l c o lo u r vision . S u b jec ts w e re p a id fo r th e ir p artic ip a tio n.
Ap p ara tu s an d S tim uli T h e ex p er im en t w as c a rrie d ou t o n a V ig le n 4 86 /3 3 m icro c om p ute r w ith a S V G A co lou r m o nito r. T h e ap p ro xim a te v ie w in g d istan c e w a s 70 ce ntim e tre s. A ll stim u li w e re p re se n te d in V G A m e d iu m re s o lu tio n g r a p h ic s m o d e . R e sp on se s w e re m ad e w ith a K raft K C 30 jo y stic k in te rfa ce d to th e co m p ute r via a stan d ard g am e p ort. R e ac tio n tim e s w ere c o m p u ted usin g th e ro u tin e s pu b lish e d by B ov e n s an d B ry sb ae rt (1 9 9 0). T h e stim u li w e re so lid d a rk g re y c irc les of th re e differe n t siz es (d es crib ed a s siz es 1 , 2 , a nd 3 ). A t a v iew in g d ista n c e o f a bo u t 70 c m , th e d ia m e te rs o f th e circle s (in de g re e s of visu a l a ng le ) w ere 0.4 9 d eg re es fo r siz e 1 , 0.7 4 d eg re es fo r siz e 2, an d 0 .9 8 d eg ree s fo r siz e 3. T h e circ le s ap p e are d on a lig h t g re y ba c kg ro u n d in tw o of fou r po ssible lo c atio n s, w ith fo u r da rk g re y arro w s (p o intin g u p , d o w n , le ft, a n d rig ht fro m th e c e ntre o f the scre en ) u sed to m a rk th e fo u r p ossib le lo ca tio n s. T h e d ista n ce fro m th e tip o f th e le ft p o in ting a rrow to th e tip o f th e rig h t po in tin g a rro w a n d from th e tip o f the u p w a rd po intin g arro w to th e tip o f th e d o w n w a rd po in tin g a rrow w as 3 .0 3 d e g re e s. E ac h c irc le w as ce n tre d on a po int 1 .0 6 de g ree s from th e tip of its arro w m ark e r.
Proced u re S ub je cts w e re to ld tha t d urin g e ac h tria l, th ey w o u ld see tw o c irc les on th e scre en an d tha t o n e c irc le w ou ld b e la rge r th an th e o th e r. T h e su b je c t’ s ta sk w a s to in d ic a te th e loc a tio n o f th e la rge r c irc le a s q uic k ly as po ssib le b y m ak in g a sp a tia lly c o m p a tib le m o v e m e n t o f th e jo y stic k (U P , D O W N , L E F T , o r R IG H T ). E a ch p a ir of trials b eg a n w ith a v isua l p rom p t fo r th e su bje cts to p ress th e sta rt ke y . Im m e dia te ly after th e sta rt k ey w a s p re sse d, th e fo ur a rrow m ark er s ap p ea re d o n th e sc ree n . T h e a rrow s rem ain ed v isib le th ro u gh o u t ea ch tria l: 15 0 0 m se c a fte r the sta rt ke y h ad be en p resse d, th e first o f tw o d isp lay s (th e prim e ) w as pre se nte d. O n e c irc le w a s d ispla y ed at th e tip of e a ch o f tw o a rro w s. In th e p rim e d isp la y , the larg er (targ e t) circ le w as a lw a y s a size 3 c ircle an d th e sm a lle r circle w a s alw a ys siz e 2 .
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T h e p rim e d isp lay re m a ine d o n the sc ree n u ntil a re sp o n se w a s m a d e (i.e. the su b jec t m o v e d th e jo y stic k u p , d ow n , le ft, o r righ t). A u ditory fee d ba c k allo w ed 2 th e su b je ct to d istin g u ish b e tw e en c orre ct resp o n ses a n d e rrors. F o llo w in g the re sp on se , the disp lay v an ish ed , lea v ing on ly th e arro w s o n th e sc ree n fo r 3 5 7m se c. T h e p ro b e d isp lay w a s th e n p rese n te d . A s in th e p rim e , th ere w e re tw o c irc les, o n e larg er th a n the oth er. T he la rg e r c irc le w as alw ay s size 2 a n d the sm aller circle w as a lw a ys size 1 . T h e p ro be disp la y c irc les also re m a in e d o n the sc ree n un til th e su b je c t m ad e a jo ystick re spo n se. T h e scre e n w as th e n c lea red a nd th e p ro m p t to p re ss the start ke y rea p pe a red .
D esig n T he p ro b e trials c o nta in e d a w ith in -su b jec t prim in g tria ls fac tor; trials w e re d ivid ed b e tw e e n co n tro l a nd ig no re d re p e titio n . O n c o ntro l trials, th e tw o p ro be c irc les a pp e a re d in th e tw o lo c atio ns th at ha d n ot be e n o c cu p ie d by eith er c irc le o n the pre vio u s p rim e tria l. O n ig n ore d rep e tition trials, the p ro b e ta rge t (size 2 c irc le) alw a ys a pp e a re d in th e lo c atio n tha t h ad b ee n o c cu p ie d b y th e ide n tic al p r im e d istr a c to r. T h e re w e re 1 8 in itia l p ra ct ic e tria ls , f o llo w e d b y 9 0 e xp e rim e nta l tria ls. In a n a tte m p t to co n ce a l th e n eg a tiv e prim in g m an ip ula tio n , o n ly o n e-th ird o f the e xp e rim en tal trials w ere ign o re d re p etitio n trials. T rials w e re p rese n te d in b lo c k s o f n in e , an d w ith in e ac h blo ck , th e th ree ign o red re pe titio n tria ls w e re alloc a ted ra n d om ly . T h e lo c a tio n s u sed in the prim e d isp la y w e re se lec ted a t ra nd o m o n all tria ls; th e lo ca tio n s o f th e p ro b e stim u li w e re d ete rm in ed b y th e tria l ty p e .
R ES U LT S P ro b e D isp lay R Ts an d Erro rs M ea n o f m ed ia n R T s an d e rror p e rc en tag e s fo r the tw o U N E X g ro u p s a re sh ow n in F igs 2 A an d 2 B . T h ere w er e la rge r n e ga tiv e p rim ing effec ts o n R T an d e rro rs in th e L o w U N E X g ro up th a n in th e H ig h U N E X g ro up . T h e m ea n n e g ativ e p rim in g R T e ffec ts, ob ta in e d b y su b tra ctin g the m ea n ig no re d re pe tition R T fro m th e m ea n co n tro l R T , w e re ±2 7.4 m se c for the L o w U N E X g rou p (c om p ara b le to th e ±2 6m se c e ffec t o b tain ed b y T ip pe r et a l., 1 9 95 ) a nd ±1 4.4 m se c fo r the H ig h U N E X gro u p. T h e m e a n n e ga tive p rim in g e rro r p erc e n ta g e effe cts, ob tain e d in th e sa m e w ay , w ere ±0 .9 5 fo r the L o w U N E X g rou p a n d ±0 .5 7 fo r the H ig h U N E X g rou p . T h e m ed ia n R T s w ere a n aly sed in a 2 ´ 2 m ixe d a n aly sis o f v a ria n c e (A N O V A ). T h e b etw e en -su bje cts fa cto r w as U N E X g rou p a nd th e w ith in 2
A n er ro r w a s re co rd e d if n o re s p o n s e w a s m ad e w ith in 3 .5 s e c o n d s o f th e c irc l e p re s e n t at io n , o r if
th e d ire c ti o n o f t h e j o y s tic k m o v e m e n t d e v ia t e d b y m o re th a n 4 5 d eg re e s (to e it h e r s i d e ) f ro m th e c o rr e c t d i re c t io n .
Downloaded by [Adams State University] at 11:05 10 December 2014 FIG . 2 (A an d B ).
M e a n s o f m e d ia n re s p o n s e t im e s (R T s ) a n d e rr o r p e rc e n ta g e s fo r th e h ig h a n d
lo w U N E X s u b j e ct g ro u p s .
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su b jec ts fac tor w as p rim ing co n d itio n (co n tro l vs. ig no re d rep e titio n). T he a na ly sis re v e aled a sign ifica n t p rim in g c on d itio n m a in e ffec t [F (1 ,5 5 ) = 9 0 .3 , M S E = 13 7 .6 , P < .0 0 0 1] an d a sig n ifica n t p rim in g c o nd itio n ´ U N E X g rou p in te ra ction [F (1 ,5 5 ) = 8 .8 , M SE = 1 3 7 .6 , P < .0 0 5]. S e p ara te o ne -w ay A N O V A s re ve a le d sig n ific an t ne g ativ e p rim in g in the R T da ta o f bo th th e H igh U N E X g rou p [F (1 ,2 8 ) = 2 9 .6 , M S E = 1 01 .3 , P < .0 00 1 ] an d the L o w U N E X g rou p 3 [F (1 ,2 7 ) = 5 9 .9 , M S E = 1 7 5.3 , P < .0 0 01 ]. T h e m e d ia n erro r p e rce n ta g es w e re a lso su b m itte d to a 2 ´ 2 A N O V A , w h ic h re v e a le d a n o v e r a l l n e g a t iv e p ri m i n g e f fe c t i n th e e r r o r r a t e s [F (1 ,5 5 ) = 4 .5 , M S E = 3 .6 , P = .0 4 ] b ut n o inte rac tio n b etw ee n n e ga tive p rim ing a nd U N E X g ro up .
C O N C L U S IO N S T he p re sen t stud y h as fo c u sed o n the in hib itio n m e ch a n ism b y rem o vin g a ny p e rc e p t u a l m is m a tc h b e tw e e n p ri m e d is tra c to r a n d p ro b e ta rg e t in th e e xp e rim e nta l ta sk . T h e resu lts a re c lea r: N e g a tiv e prim in g e ffe c ts are sm alle r in th e hig h U N E X su b jec ts, e ve n w he n the ign o red p rim e a n d su b se q ue n t p ro be a re id e n tic al o b jec ts, su p p or tin g th e c laim o f o th e rs (e .g . B e ec h e t a l., 19 9 1 , 1 9 89 a ,b ) th at sc h izo typ a l su bje cts a re le ss a ble to in h ib it d istra ctin g in fo rm a tio n . In ad d itio n , th is w o rk h as de m o n strate d th a t sc h iz o typ y d iffe re nc es in in hib itio n ca n be d ete cted w ith a n ew ty pe o f n e g ativ e p rim in g task . A ll p re v io u s stu d ie s o f ne g ativ e p rim ing in sc hiz o ty p al g rou p s h a ve re qu ire d su b jec ts to id en tify a stim u lus, su ch a s na m in g a co lo ur, w o rd , o r p ic ture . T h e pre sen t e xp e rim e nt h a s d e m o n stra ted th at in d iv id ua l d iffe ren c e s in th e u se of in h ibition d u rin g sele c tio n a ffe ct low e r le v e l lo ca lisatio n re sp on se s as w e ll a s h igh e r le v el se m a n tic pro c esse s. T h e se re su lts are clea rly c o nsisten t w ith th e e xiste nc e o f an inh ib ito ry d e fic it in sch izo p h ren ia an d re la ted state s. T h e R T d ata c ollec ted h e re in dic a te tha t the lo w e r lev e ls o f inh ibitio n o b serv e d in th e sch izo ty pa l gro u p do n o t slo w o r im p a ir ta sk p e rform an c e, w h ic h m a y m e an tha t sch izo ty p al ind iv idu a ls a c hie ve e ffic ie n t targ et se lec tio n v ia o th e r e x cita to ry p ro c e sses. It is assu m e d h ere th at in div idu a ls w ith sc hiz oty p a l p e rson a lities are m o re lik e ly to d ev e lo p p sy ch o tic d iso rd e rs th a n in d iv id u als w h o are n ot sc h iz o typ a l, a nd th at the y a lso sh a re so m e c ha ra cte ristics (in clu d in g co g n itiv e p ro ce ssin g a ttribu te s) w ith pe o ple w ho h a ve d ev e lo pe d p syc h o ses (e .g . C la rid g e , 1 9 85 ). It m ay b e the n th at m ost p e op le w h o d e v elo p p sy c h o tic sy m p to m s alre a d y h av e a re la tiv e ly la rg e n u m b e r o f 3
A lt h o u g h t h e s e d a ta d e m o n s tra t e t h a t h ig h U N E X s u b je c ts u t ili se le s s i n h ib it io n th a n lo w U N E X
s u b je c t s, i t is re c o g n is e d th a t th is a s so c ia ti o n m ay n o t b e u n iq u e to U n u s u a l E x p e rie n ce s s ca l e a n d c o u l d re fl ec t a c l o s e r as s o ci a tio n b e tw e e n i n h ib iti o n a n d an o th er c o rr e la te d m ea s u re o f s c h i z o ty p y . U n fo rt u n a te ly , h o w e v e r, t h e s e le c ti o n o f e x tre m e U N E X g ro u p s in t h e p re s e n t s t u d y m e a n s th a t U N E X a n d t h e o th e r O L IF E s c a le s (w h ic h h a d c o n ti n u o u s d i s trib u t io n s in th e p re se n t s a m p l e) ca n n o t b e v a li d l y c o m p a re d a s c o rr e la te s o f th e in h i b i tio n m e a s u re .
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sym p tom -re late d p e rson a lity tra its. It is p e rh a p s o nly if an d w he n sc hiz op h re nia de v elo p s in su ch ind iv id u a ls, an d w h e n oth er (n orm ally co m p e nsa to ry) c og n itiv e pro c esse s b e g in to d e te rio ra te , th a t th e re du c e d in h ib ition see n in he a lth y sch izo ty pa l su bje cts a ssum es a n y fu n ctio na l sig n ific an c e . Ind iv id u a ls w h o de v elo p c lin ic a l sym p tom s m ay th en su ffe r th e e ffec ts of re d u ce d c og n itiv e in h ib ition , w hic h is e x po se d a n d co m po u n d ed by o th er co g nitiv e de fic its, a n d ex p erie nc e th e in fo rm a tio n o v e rlo a d th at p atien ts ha v e de sc rib e d. It is a lso im p o rtan t to n o te tha t th is re se arc h ca n sa y little ab o ut in div idu a l differe n ce s in th e p erc ep tu a l rev iew p ro ce ss; th e de tec tio n o f re du c ed in hib itio n in sc hiz oty p a l p e rson a lities d o es no t ex c lu d e th e po ssib ility th at th e o p era tio n o f pe rc ep tua l re vie w p ro c e sses is also asso c iate d w ith sc hiz oty p y . A de fic it in th e ca p ac ity to lin k p e rce p tua l e v en ts a c ro ss tim e c ou ld b e re lev a nt to th e sy m p to m s of sc hiz op h re n ia an d to sc h iz o ty p y . S c hiz oty p y d iffere n ce s in n eg a tiv e p rim in g ta sk s th a t inv o lve p erc e ptu al rev iew w ill th e re fo re b e in ve stig a ted in fu tu re re se arc h . M a n u s c ri p t re c e i v e d 1 2 J u n e 1 9 9 6 R e v i se d m a n u s cr i p t r ec e iv e d 2 9 O c t o b e r 1 9 9 6
R EFE R E N C ES B a ru c h , J ., H e m s le y , D ., & G ra y , J .A . (1 9 8 8 a ). L at e n t in h ib i ti o n a n d `p s y c h o t ic -p ro n e n e s s’ in n o rm a l su b je c ts . P e r s o n a lit y a n d In d iv i d u a l D i ffe r e n ce s , 9 , 7 7 7 ±7 8 4 . B a ru c h , J ., H e m s le y , D ., & G ra y , J .A . (1 9 8 8 b ). D iffe re n tia l p e rf o rm a n c e o f ac u te a n d c h r o n ic s c h iz o p h re n ic s in a la t en t i n h ib it io n ta s k . J o u r n a l o f N er v o u s a n d M en ta l D is e a se s , 1 7 6 , 5 9 8 ± 6 0 6. B e e ch , A ., B a y lis , G ., S m it h s o n , P ., & C l ar i d g e , G . (1 9 8 9 a ). In d iv id u a l d i ff e re n c e s in s c h iz o ty p y a s r ef l e c te d in m e a s u re s o f c o g n it iv e in h ib iti o n . B r i tis h J o u r n a l o f P s y ch o lo g y , 2 8 , 1 1 7 ±1 2 9 . B e e ch , A ., & C la rid g e , G . (1 9 8 7 ) . In d i v i d u a l d i ff e re n c e s in n e g a tiv e p rim i n g : R e la t io n s w i th s c h iz o ty p a l p er so n al ity tra it s. B r iti s h J o u r n a l o f P sy c h o l o g y , 7 8 , 3 4 9 ±3 5 6 . B e e ch , A ., M c M a n u s , D ., B a y l is , G ., T i p p e r, S .P ., & A g a r, K . (1 9 9 1 ). In d iv id u a l d iffe re n c e s in c o g n i tiv e p r o c e s s es : T o w a rd s a n e x p l a n a ti o n o f s c h iz o p h re n ic s y m p t o m a t o lo g y . B r iti s h J o u rn a l o f P s yc h o l o g y , 8 2 , 4 1 7 ±4 2 6 . B e e ch , A ., P o w e l l, T ., M cW il lia m , J ., & C la rid g e, G . (1 9 8 9 b ). E v id en c e o f re d u c e d `c o g n iti v e i n h ib it io n ’ in s c h i zo p h re n i a. B r it is h J o u r n a l o f P s yc h o lo g y, 2 8 , 1 0 9 ±1 1 6 . B le u le r, E . (1 9 5 0 ). D e m e n tia P r a e c o x o f th e g r o u p o f s c h iz o p h r e n i a s . N e w Y o r k : In t er n a ti o n a l U n iv e rs iti e s P re s s . (O rig in a l w o rk p u b lis h e d 1 9 1 1 ) B o v e n s , N ., & B ry s b a e rt, M . (1 9 9 0 ). IB M P C /X T / A T a n d P S / 2 T u rb o P a s c a l tim i n g w it h e x te n d ed r es o lu tio n . B e h a v io r R e s e a r c h M e th o d s , In st ru m e n t s a n d C o m p u te rs , 2 2 , 3 3 2 ±3 3 4 . B ra ff , D .L ., H ea t o n , R .K ., K u c k , J ., C u l lu m , M o ra n v i lle , J., G ra n t, I. , & Z is o o k , S . (1 9 9 1 ). T h e g e n er al iz e d p at te rn o f n eu ro p s y c h o l o g ic a l d ef ic its in o u tp a tie n ts w i th c h ro n i c s c h i z o p h r en ia w i th h e te ro g e n e o u s W is c o n s in C a rd S o rti n g T e s t re s u lts . A r c h iv e s o f G e n e r a l P sy c h ia try , 4 8 , 8 9 1 ± 8 9 8. B u l le n , J .G ., & H em s le y , D .R . (1 9 8 4 ). P s y c h o tic is m an d v is u a l re c o g n i tio n th re s h o ld s . P e rs o n a li ty a n d In d i v id u a l D iff e re n c e s, 6 , 7 3 5 ±7 3 9 . C h a p m a n , L ., C h a p m an , J .P ., & M il le r, G .A . ( 1 9 6 4 ). A th e o ry o f v e rb a l b e h a v io r i n s c h i zo p h re n ia . P r o g r e ss in E x p er i m e n ta l P e r s o n a lit y R e s ea r c h , 1 , 4 9 ±7 7 . C la rid g e, G .S . (1 9 8 5 ). O r ig i n s o f m e n t a l i lln e s s . O x fo rd : B la c k w e ll .
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C l ar id g e , G .S . (1 9 8 7 ). `T h e s c h i z o p h r en ia a s n e rv o u s t y p e s’ re v is i te d . B ri tis h J o u r n a l o f P s y c h i a t ry , 1 5 1 , 7 3 5 ±7 4 3 . C l a r i d g e , G .S .,
&
B ro k s , P . ( 1 9 8 4 ) . S c h i z o t y p y
and
h e m i s p h e re
f u n c t i o n : I. T h e o r e t i c a l
c o n s id e ra tio n s a n d t h e m e a s u re m e n t o f s c h iz o t y p y . P e r s o n a l ity a n d In d iv i d u a l D i ffe r e n ce s , 5 , 6 3 3 ±6 4 8 . C l ar id g e , G .S ., C la rk , K .H ., & B e ec h , A .R . (1 9 9 2 ). L at e ra liz a ti o n o f th e `n e g at iv e p ri m i n g ’ e ff e c t: R e la t io n s h ip s w ith s c h i zo ty p y a n d w ith g e n d er . B r iti s h J o u r n a l o f P sy c h o lo g y , 8 3 , 1 3 ±2 3 . C o rn b l at t, B .A ., L e n z e n w e g e r, M .F ., & E rl e n m e y e r- K im l in g , L . (1 9 8 9 ). T h e C o n tin u o u s P e rf o rm a n c e T e st , Id e n tic a l P a irs V e rs io n II : C o n tra s tin g a tte n ti o n p ro fi le s in s c h iz o p h re n ic a n d d ep re s s ed p a t ie n t s. P s y c h ia tr y R e se a r ch , 2 9 , 6 5 ±8 5 . D e l a C a s a , L .G ., R u iz , G ., & L u b o w , R .E . (1 9 9 3 ). L a te n t in h ib it io n a n d re c a ll /re c o g n it io n o f
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irre l e v a n t s tim u li as a fu n c tio n o f p re -e x p o s u re d u ra tio n i n h i g h a n d lo w p sy c h o ti c -p ro n e n o rm a l s u b je c ts . B r iti sh J o u r n a l o f P s y c h o lo g y , 8 4 , 1 1 9 ±1 3 2 . E y s e n c k , H .J ., & E y s e n c k , S .B .G . (1 9 7 5 ). M a n u a l o f E y s e n ck p e r s o n a lit y q u e s ti o n n a ir e. L o n d o n : H o d d e r & S to u g h t o n . F r ith , C .D . (1 9 7 9 ). C o n s c io u s n e s s , in fo r m a ti o n p ro c es s in g a n d s ch iz o p h re n ia . B ri tis h J o u r n a l o f P s y c h ia t r y, 1 3 4 , 2 2 5 ±2 3 5 . H e m s le y , D .R . (1 9 8 7 ). A n e x p er i m e n ta l p s y c h o lo g i c a l m o d e l fo r s c h i z o p h r en ia . In H . H a fn e r, W .F . G a tta z , & W . J a n z a rik (E d s .) , S e a r c h f o r th e c a u s e s o f s c h i z o p h r e n ia . H e id e lb e rg : S p ri n g e r. H e m s le y , D .R . (1 9 9 4 ). P e rc ep tu a l a n d co g n i tiv e a b n o rm a lit ie s a s th e b a s es fo r sc h iz o p h re n ic s y m p to m s . In A .S . D a v id & J .C . C u tti n g (E d s .) , T h e n eu r o p s y c h o l o g y o f s c h i z o p h r e n ia . H o v e , U K : L a w re n c e E rlb a u m A ss o c ia te s L td . K a h n e m a n , D ., T r ei s m a n , A ., & G ib b s , B .J . (1 9 9 2 ). T h e re v ie w in g o f o b je c t fil e s: o b j e ct -s p e c ifi c in te g ra tio n o f in fo rm at io n . C o g n it iv e P s y c h o lo g y , 2 4 , 1 7 5 ±2 1 9 . L ap la n te , L ., E v e re tt, J., & T h o m a s , J . (1 9 9 2 ). In h ib it io n t h ro u g h n e g a tiv e p r im in g w i th S t ro o p s tim u li i n sc h iz o p h re n ia . B r iti sh J o u r n a l o f C li n i c a l P sy c h o l o g y, 3 1 , 3 0 7 ±3 2 6 . L en z e n w e g er , M .F ., C o rn b la t te, B .A ., & P u t n i ck , M . (1 9 9 2 ). S c h i zo ty p y a n d su s ta in e d a tt e n t io n . J o u r n a l o f A b n o r m a l P s y c h o l o g y , 1 0 0 , 8 4 ±8 9 . L en z e n w e g er , M .F ., & K o rfin e , L . (1 9 9 4 ) . P e rc e p tu a l a b er ra tio n s , s c h iz o t y p y an d th e W is c o n s in C a rd S o rtin g T a sk . S c h i zo p h r e n ia B u ll et in , 2 0 , 3 4 5 ±3 5 7 . M as o n , O ., C la ri d g e, G .S ., & J a c k s o n , M . (1 9 9 5 ). N e w s c a le s fo r th e a s s es s m e n t o f s c h i z o ty p y . P e r s o n a lit y a n d In d iv i d u a l D iff e re n c e s , 1 8 , 7 ±1 3 . M cG h ie , A ., & C h a p m a n , J. (1 9 6 1 ). D i so rd e rs o f a tt e n t io n an d p e rc ep ti o n i n e a rly s c h iz o p h re n ia . B r i tis h Jo u rn a l o f M e d ic a l P s y c h o lo g y , 3 4 , 1 0 3 ±1 1 5 . M ill ik en , B ., T ip p e r, S .P ., & W e a v e r, B . (1 9 9 4 ). N e g a ti v e p ri m in g in a s p a ti a l lo c al iz a tio n t a sk : F e a tu re m i s m at c h i n g a n d d is tra c to r in h ib it io n . J o u r n a l o f E x p e r im en ta l P s y c h o lo g y : H u m a n P e r c e p t io n a n d P e r fo r m a n c e , 2 0 , 6 2 4 ±6 4 6 . N e i ll , W .T . (1 9 7 7 ) . In h ib i to ry
a nd
fa c il i ta t o ry
p ro c e s s e s in
se le c t iv e
a tt e n ti o n . J o u r n a l o f
E x p e r im e n ta l P sy c h o l o g y : H u m a n P e r c ep ti o n a n d P e rf o r m a n c e , 3 , 4 4 4 ±4 5 0 . O b io ls , J .E ., G ar c i a -D o m in g o , M ., d e T ri n c h e ri a, I., &
D o m e n e c h , E . (1 9 9 3 ). P s y c h o m e tric
s c h i zo ty p y a n d s u s ta in e d a tte n ti o n in y o u n g m a l es . P e r s o n a lity a n d In d iv i d u a l D iff e re n c e s , 1 4 , 3 8 1 ±3 8 4 . P e t e rs, E .R ., P i c k e ri n g , A .D ., &
H e m sl e y , D .R . (1 9 9 4 ). `C o g n iti v e in h i b i tio n ’
and
p o s it iv e
s y m p to m a to lo g y i n s c h i z o t y p y . B r iti sh J o u r n a l o f C li n i c a l P sy c h o l o g y, 3 3 , 3 3 ±4 8 . R o s e n b a u m , G ., S h o re , D .L ., &
C h a p in , K . (1 9 8 8 ). A tt e n t io n d e fic it in s c h i z o p h re n ia a n d
s c h i zo ty p y : M ar k e r v e rs u s s y m p t o m v a ria b le s . Jo u rn a l o f A b n o rm a l P s y c h o l o g y, 9 7 , 4 1 ±4 7 . S p rin g , B .J . (1 9 8 0 ). S h ift o f a tt e n t io n in s ch iz o p h re n ic s , s ib li n g s o f s c h i z o p h re n ic s a n d d e p re s s e d p at ie n ts . J o u r n a l o f N e r v o u s a n d M e n t a l D i se a s e, 1 6 8 , 1 3 3 ±1 4 0 . T ip p e r, S .P . (1 9 8 5 ). T h e n e g a tiv e p ri m in g e ff e c t: In h i b i to ry e ff e c ts o f i g n o re d p ri m e s. Q u a r t er l y J o u r n a l o f E xp e r im e n ta l P s yc h o l o g y, 3 7 A , 5 7 1 ±5 9 0 .
S C H IZ O T YP Y A N D D IS T R A CT O R IN H IB IT IO N
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T ip p er , S .P ., & B a y l is , G .C . (1 9 8 7 ). In d iv id u al d iffe re n c e s in s e le c ti v e a tte n ti o n : T h e r el a tio n o f p rim i n g an d in te rf e re n c e to c o g n i tiv e f ai lu re . P e r s o n a l ity a n d In d iv id u a l D iffe r e n c e s, 8 , 6 6 7 ±6 7 5 . T ip p er , S .P ., & C ra n st o n , M . (1 9 8 5 ) . S e le c ti v e at te n tio n a n d p rim in g : In h ib it o ry a n d f ac i lit a to r y e ff e c t s o f ig n o re d p rim e s . Q u a r te r ly J o u r n a l o f E xp e r im en ta l P s y c h o l o g y, 3 7 A , 5 9 1 ±6 1 1 . T ip p er , S .P ., W e a v e r, B ., & M il lik e n , B . (1 9 9 5 ). S p a tia l n e g a tiv e p rim in g w ith o u t m i s m at c h i n g : C o m m e n t o n P a rk a n d K a n w is h e r (1 9 9 4 ). J o u r n a l o f E x p e r i m e n ta l P s y c h o lo g y : H u m a n P e r ce p ti o n a n d P e rf o r m a n c e, 2 1 , 1 2 2 0 ±1 2 2 9 . W il k i n s , S ., &
V e n a b le s , P .H . (1 9 9 2 ). D is o rd er o f a t te n t io n in i n d iv id u a ls w ith s c h iz o t y p a l
p e rs o n a li ty . S c h iz o p h re n i a B u l le ti n , 1 8 , 7 1 7 ±7 2 3 . W i ll i am s, L .M . ( 1 9 9 5 ). F u r th e r e v i d e n c e fo r a m u l ti d im e n s i o n a l p e rs o n a li t y
d is p o s it io n
to
s c h iz o p h re n ia i n te rm s o f c o g n it iv e i n h ib it io n . B r it is h Jo u rn a l o f C lin ic a l P sy c h o l o g y, 3 4 ,
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1 9 3 ±2 1 3 .
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Cognitive Neuropsychiatry Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/ pcnp20
Brief Report Reduced Negative Priming in Schizotypal Subjects does reflect Reduced Cognitive Inhibition Frances L Watson & Steven P Tipper Published online: 09 Sep 2010.
To cite this article: Frances L Watson & Steven P Tipper (1997) Brief Report Reduced Negative Priming in Schizotypal Subjects does reflect Reduced Cognitive Inhibition, Cognitive Neuropsychiatry, 2:1, 67-80, DOI: 10.1080/135468097396423 To link to this article: http://dx.doi.org/10.1080/135468097396423
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C O G N IT IV E N E U R O P S Y C H IA T R Y , 1 9 9 7 , 2 (1 ), 6 7 ±7 9
B r ie f R e p o r t R e d u c e d N e g a tiv e P r im in g in S c h iz o ty p a l S u b je c ts d o e s r e fle c t R e d u c e d C o g n itiv e In h ib itio n Downloaded by [Adams State University] at 11:05 10 December 2014
F ra nc e s L . W a tso n a n d S te v e n P . T ipp e r S ch o ol o f P sy ch o log y , U n iv ersity of W a le s, B an g o r, U K
N u m e ro u s s tu d ie s h a ve s ug g es te d , v ia th e inter p re ta tio n o f th e ne g a tive p rim ing e f fe c t a s a m ea s ur e o f c og n itiv e in h ib itio n , tha t sc h iz o ty pa l su b je c ts a r e le ss ab le to in hib it irre le v a nt dist ra c tin g inf or m a tion . R ec e n t r es ea r ch h as r ev e ale d, h o w e ve r, th at n e ga tiv e p rim in g e ff ec ts c a n b e ca u se d b y tw o q uite d iff er e nt p ro c es se s: d ist ra cto r in h ib itio n a n d p er c ep tua l r e v ie w . T h e r ef or e , u n e q uivo c a l c o nc lu s io ns c o n ce rn in g le ss e ff ic ien t inh ib ition in s c hizo typ a l in d iv id u a ls a re n o t po s sib le f ro m p r e v io u s re se a r c h . T h e p r e s e n t e x p e r im e n t m in im is e s th e c o n tr ib u t io n o f p e rc e p tu al re v ie w to n e ga tiv e p rim in g a n d d e m o ns trate s th a t w he n a pu r er m ea s ur e o f in h ib itio n is ta k en , s ch iz o ty p al s ub je c ts ar e in d ee d le ss a ble to in h ib it irr e le v an t d istra c tin g st im u li.
IN T R O D U C TIO N A n in a bility to ign o re irre lev a n t stim u li h as be en re g a rde d a s a ce n tra l u nd e rlyin g fe a tu re o f sch izo p hr en ia sinc e th e d iso rd er w as first d e scr ib e d (B le ule r, 19 1 1 / 19 5 0 ): ``T h e sele ctio n w h ic h a tte ntio n e xe rcise s o v er n orm al se n so ry im p re ssio n s m a y b e red u ce d to z ero , so tha t a lm o st ev e ry th in g tha t m e e ts the se n ses is re g iste red .’ ’ L a te r, M cG h ie an d C h a p m a n (1 9 61 ) p ro po se d ``a b rea k d ow n in th is selec tive -inh ib ito ry fu nc tion o f a tte ntio n ’ ’ th a t lea d s to an o v e r-in clu sio n o f irre le v an t in form atio n an d th e n , to se c on d a ry d istu rba n ce s in pe rc ep tio n a n d th o u g ht. F rith (19 7 9 ) h a s a lso p ro po se d a ``d e fe c t in th e m ec h an ism tha t lim its a n d co n trols th e c o n te n ts o f c o n scio u sne ss’ ’ as the ba sis fo r the po sitiv e sy m p to m s (h a llu c in a tio n s, d e lu sio ns, th o u g ht d iso rd er) o f sch izo p hr en ia.
R e q u e s ts fo r re p ri n t s s h o u ld b e se n t t o D r F ra n c e s W a t so n o r P ro fe s s o r S t ev e n T ip p e r, S c h o o l o f P s y c h o l o g y , U W B , B a n g o r, G w y n e d d L L 5 7 2 D G , U K . T h is r es e a rc h w a s s u p p o r te d b y th e H ig h e r E d u c a tio n F u n d in g C o u n c il fo r W a le s . W e ar e g ra te fu l to D r M . J ac k s o n a n d P ro fe s so r J .M .G . W ill ia m s fo r a c c e s s t o t h e i r s u b je c t s a m p l e , a n d to B r u c e W e a v e r fo r te c h n ic a l s u p p o rt.
Ó
1 9 9 7 P s y c h o l o g y P re s s , a n im p ri n t o f E rlb a u m (U K ) T a y lo r & F ra n c is L t d
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S u ch in hib itio n-b a sed th eo ries o f sch izo p h ren ia a re su p p orte d b y ex p e rim en tal ev id en c e; p eo p le w ith sch iz op h ren ia p e rform po o rly o n ta sks th at d em a n d the sele ction o f re lev a nt in fo rm a tio n fro m a n irre lev a n t b ac k gr ou n d , c om p a re d to he a lth y c o n tro ls. F u rth e rm o re, h e althy in div idu a ls w h o re p ort p ers on a lity traits th a t rese m b le p sy ch o tic sy m p tom s (sc h izo typ a l p e rso n a lities) a lso p e rfo rm p o orly on the se ta sk s re lative to lo w sc h iz o typ a l in d iv id ua ls. P a tie nts w ith sch izo p h re n ia an d sch izo ty pa l su b jec ts h a ve b e en rep o rte d to sho w re la tiv e d eficits on th e W isc o ns in C ard S o rtin g T e st (B raff et a l., 1 9 91 ; L en z en w e g er & K o rfin e, 1 9 94 ), laten t in hib itio n (B aru c h, H em sley , & G ra y , 1 9 88 a ,b ; D e la C a sa , R u iz, & L ub o w , 1 9 9 3), th e in h ib ition of in ap p ro p ria te m ea n in g s o f a m b ig uo u s w o rd s (B u llen & H em sley , 1 9 8 4; C h a p m a n , C ha p m a n , & M ille r, 1 9 64 ), c ro ss-m o da l set sw itc h in g (S prin g, 1 98 0 ; W ilk in s & V e n a ble s, 1 9 92 ), sim p le re ac tio n tim e (R T ) p rep a rato ry in terv a l cro ss-o v er (R o sen b au m , S h o re , & C h a pin , 1 9 8 8), a nd v ig ila n ce (C P T ) (C o rn b latt, L en z en w e g er, & E rle n m e y er-K im lin g , 1 9 89 ; L e nz e n w e g er, C o rnb latt, & P u tn ick , 1 9 9 2; O bio ls, G a rc ia -D o m in g o , de T rin ch e ria , & D o m e ne c h , 1 9 9 3 ). T h ese rep o rte d p a rallels s u g g e s t th a t sc h iz o ty p a l su b je c ts e x p re s s t h e sa m e fo r m o f a tte n tio n a l in e ffic ie n c y a s p a tie n t s w ith s c h iz o p h r e n ia , a n d th a t sc h iz o ty p a l g r o u p d iffe re nc e s in sele ctive a tte n tio n p rov id e a m o d e l fo r a tte ntio n al d e fic its in sc hiz o p hre n ia . S u ch fin d ing s p ro v ide stro n g su p po rt fo r th e d im e n sio n a l h yp o th esis o f p sy ch o sis (e .g . C larid ge , 1 9 8 5, 1 9 8 7). T h is p ro p os es th a t a n u n d erly in g c on tin uo u s p re disp o sitio n to d e v elo p sch izo p h ren ia ex ists w ith in th e h ea lth y p o pu la tio n a nd th a t the p re disp o sitio n h as bio log ic al, p erso n ality , a nd co g nitive m an ifesta tio ns . C la rid g e (1 9 85 ) sug g e sts th at m e asu re s of sch izo ty p y sim u ltan eo u sly re fle ct a h ea lthy in d iv id u al’ s pre disp o sitio n to sc h iz o p hre n ia as w ell a s sp ec ific asp e cts o f th eir p e rs on a lity . T h e rep o rte d p a ra lle ls b e tw e en co g nitive p roc e ssing in sch izo ty pa l p e rson a lities an d p e op le w h o h av e sc h iz o p hre n ia th ere fore p o in t to c om m on m ec h an ism s op e ra tin g in bo th h ea lth y a n d clinic al state s, a n d sug g ests th at e v id e nc e fro m sch izo ty p al ind iv id u als m ay b e u sed a s a m od e l fo r sch izo p h ren ia . F u rth e r e v id e n ce fo r an inh ib ito ry d e fic it in sc h iz o ph re n ia an d in sc hiz oty p al p ers on a litie s h a s c o m e fro m stu d ies of n e g ativ e prim in g, a p a rad igm th at p rov id e s a pa rtic u la rly dire ct m ea su re o f th e ca pa c ity to ign o re a n d inh ib it irre le va n t stim u li (e.g . B e e ch , B a y lis, S m ith so n , & C la rid g e, 1 98 9 a ; B e ec h , P o w e ll, M cW illiam , & C la rid g e , 19 8 9 b; L a p lan te, E v ere tt, & T h o m a s, 19 9 2 ). N e g ative prim in g re fers to th e re lative ly slo w re sp on se s th at are m ad e to re ce n tly ig no re d stim u li. W h en a stim ulu s tha t w a s p rev iou sly irrele va n t a nd ig no re d b e co m e s the ta rg et, resp o n se s to th at ta rg e t h av e b e en fou n d to be slo w e r th an u n p rim ed re sp on se s (N eil, 1 9 7 7; T ip p e r, 1 9 8 5). In a ty p ic al n e g ativ e p rim in g ta sk (e .g . T ip p er, 19 8 5 ), tw o pa rtia lly su p er im po se d p ic ture s a re p res en ted in d iffere n t c o lo u rs. T he su b je c t is instru c te d to n a m e re d p ic tu re s a nd to ign o re gre en p ic tu re s. F o r e x am ple , o n th e in itial prim e tria l, a c ha ir is sh ow n in g ree n an d ig n o re d , a nd a d o g is sh ow n in red an d na m ed . O n th e su b seq u en t
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pro b e tria l, the red ta rg et is th e p re v io u sly ig n ore d d ra w in g of a c h air an d th e gre e n d istra c to r is a ne w dra w in g . U n d e r n o rm al c on d itio n s, it ta ke s lo n g er to na m e the red c ha ir pro b e w h en it h a s be e n ig no re d o n the pre v io u s tria l (ig no re d re p e titio n ) th a n w h e n th e d r aw i n g h a s n o t b e e n se e n b e fo re ( c o n tro l). P ara d ox ica lly , in div idu a ls w ith eithe r sch izo ty pa l p e rs on a litie s (e .g . B e ec h e t al., 1 9 8 9 a) or sch iz op h re nia (e .g . B ee ch e t a l., 19 8 9 b) ten d n ot to sho w the se slo w er re sp o nse s. In h ib ition -b a sed m o de ls o f sele ctive atten tio n (e .g . N e ill, 1 97 7 ; T ip p e r & C ra nsto n , 1 9 8 5) in te rp ret n eg a tiv e prim in g effe cts a s ev id en c e fo r d istra cto r in h ib ition , w h ic h is th ou g h t to fa cilita te th e selec tion a nd p ro c e ssin g o f relev a n t in fo rm a tio n . It is a ssu m e d th a t th e re p rese n tatio n o f a n in hib ited d istra cto r is le ss ac ce ssib le fo r fu rthe r p ro ce ssin g, w h ich resu lts in sig n ific an tly lon g e r re spo n se tim e s if a d istra cto r b ec o m e s th e n e x t ta rge t. T h u s, re du c e d ne g ativ e p rim in g effec ts in sc hiz o ph re n ia an d sch izo ty py h av e b ee n in te rp rete d a s ev id en c e fo r re d u ce d co g n itiv e in hib itio n in the se gro u p s. T his is co n siste n t w ith th e pre d o m ina n t v iew o f atten tio n in sch izo p h ren ia, n am ely , th a t in d iv id ua ls w ith sch izo p h ren ia e x pe rien c e a bre ak d o w n in in h ibito ry c on tro l p ro ce sse s an d a re un a ble to in hib it d istra ctin g in form atio n.
PE R C EP TU AL R EV IE W O R IN H IB IT IO N ? A p ro b lem fo r th e fore g o in g in te rp retatio n is th a t pre v io u sly re p o rte d n eg a tiv e prim in g e ffec ts m ay n o t u n am b ig u o u sly re flec t the in h ibitio n o f distra c tors. It w a s rec en tly rea lise d th at ne g ativ e p rim in g e ffec ts m ig h t a lso reflec t th e m o re c o m p le x p ro c e s sin g th a t c o u ld re su lt fro m th e d is co v e ry o f p er c e p tu a l differe n ce s b e tw e e n the prim e distra c tor an d th e p rob e ta rg e t. K a h n em an , T re ism a n, a nd G ib bs (19 9 2 ) h av e p ro p o se d a p e rce p tu a l re v iew pro ce ss w h ich , by c om p arin g c u rre n t a n d im m e d ia tely pre c ed ing stim u li, w o u ld d isco v e r su c h distrac tor-targ e t d iffe re n ce s. T h e y su gg e st tha t a n au to m a tic rev iew of v e ry re c en t p erc e ptu al e v en ts is a p a rt of p erc e ptu a l p ro ce ssin g th a t is c ritica l fo r th e in teg ra tio n o f su cc e ssiv e p erc e ptu al ev e nts. T h is p roc e ss a cc e sses fe a tu re s o f ob je cts tha t are n o lo n g er in vie w an d lin k s cu rre nt a nd p a st in fo rm a tio n to g e th e r to p rod u c e a c oh e ren t p ic ture o f th e w o rld . O u r ow n rec e n t w o rk on se le c tiv e atten tion (M illik en , T ipp e r, & W ea v er, 1 99 4 ) c le a rly su p p orts th e hy p o the sis th a t p e rce p tu a l re v ie w c an co n trib u te to ne g ativ e p rim ing e ffe c ts in som e circu m stan ce s. F o r e x am p le , if a p ic tur e o f a c ha ir a pp e a rs first in gre e n, a s th e prim e d istra cto r, an d th en in red , as th e p ro b e targ et, the d ela y ed re sp on se to tha t ta rge t m a y re fle c t e ith e r in h ib itio n of th e c ha ir re p rese n ta tio n o r th e re so lu tio n o f th e c o lo u r m ism atc h b etw ee n th e tw o stim u li. T h e attem p t to lin k th e tw o pe rc ep tua l o b je c ts tog e th e r is h in d e re d b y th e m ism a tch in g info rm a tio n . S uc h a n in c re a se in pro c essin g tim e co u ld p ro du c e a n eg a tiv e p rim in g e ffec t th at is en tire ly u n rela te d to inh ib itio n. T h is o bse rv ation ha s a fu nd a m e n ta l im p lic a tio n fo r all stud ie s d esc ribin g ne g ativ e p rim in g effe cts. N eg ativ e prim in g effe cts c an n o lo n ge r b e assu m e d to
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re fle c t, u n eq u ivo c ally , distra c to r in h ib itio n , a nd th e d iffe re nt le ve ls o f n e g ativ e p rim in g ob se rve d in c lin ic a l an d p erso n ality gro u p s m a y in fac t reflec t a re du c ed c ap a c ity to rev iew re c e nt p erc e p tu a l ev e nts, rath er th a n a d efic it in th e ca p ac ity to in h ib it irrele va n t in fo rm a tio n . E x isting ev id en ce fo r the rela tio ns hip be tw ee n sc h izo typ y an d n e g ativ e p rim in g h a s a ll b e en o b ta ine d u sin g e x pe rim e n ta l ta sk s in w h ich in h ib itio n a nd p erc e p tu a l rev iew p ro c esse s ha v e b ee n c on fo u n de d . T h is c o nfo u nd o cc u rs w h en th e ta rge t is v e ry sim ila r (b u t n o t id en tica l) to the p rec e din g distra cto r stim u lus . In ne g ativ e p rim ing m a n ipu lation s o f th e S tro o p c o lo u r in terfe re n ce task , w h e re sc hiz o ty p y d iffe ren c es ha v e be e n rep o rte d (B e e c h e t a l., 1 9 8 9 a; B ee ch & C la rid ge , 1 98 7 ; P e ters, P ick e rin g , & H e m sl ey , 1 99 4 ), th e to -be -n am ed ta rg et c olo u r h u e in th e p ro b e d ispla y h as th e sa m e se m a ntic ide n tity a s the pre ce d ing to -b e -ign o red co lo ur w o rd . A lth o ug h th e ig no red d istra cto r w ord an d th e n am ed c olo u r h u e ta rg e t h av e th e sa m e sem an tic ide n tity, th e p rev io u sly ign o red in fo rm ation , w h ich is re p rese n te d ve rb ally b y a c olo u r n a m e , c an n o t, by d efin itio n , m atch p e rce ptu a lly w ith the v isu al h ue rep re se nta tio n of th e ta rg e t. T he re fore , so m e o f th e in d iv id u al v ariatio n in th e n eg ativ e prim in g elicite d by th is ty pe of task m ay ha v e b ee n attrib u tab le to d iffe ren c e s in th e c a pa c ity to p roc e ss this typ e o f m ism a tc h ra th e r th a n to d iffere nc e s in distra cto r in hib itio n . P erso n a lity differ en ce s in n eg a tiv e prim in g h av e a lso b ee n o b serv e d in e xp e rim e nts w h e re th e p rim e d istra cto r an d th e pro b e targ et a re the sa m e w o rd , b u t a re p re se nte d in d iffe re n t co lo urs a n d/o r in d iffere nt p o sitio ns (B e ec h , M cM an u s, B a y lis, T ipp e r, & A g ar, 1 9 9 1; C la rid g e , C la rk , & B ee ch , 1 9 92 ; T ip p e r & B ay lis, 19 8 7 ; W illia m s, 1 9 9 5). A g a in, th e se m a nip ula tio n s ine v ita bly p rod u c e p erc ep tu al d iffere n ce s b e tw e e n th e p rim e d istra c to r a n d the pro b e ta rg e t w h ic h m e a n th a t all o r som e pa rt of th e rep o rte d n eg a tiv e prim in g e ffe cts c o uld b e th e re su lt o f p e rce p tua l m ism a tch ing ra th e r th an in hib itio n . C on se q u en tly , re d u ce d n eg a tiv e p rim in g in p atie n ts w ith sc hiz op h re nia a nd sc hiz o ty p a l su b jec ts m ay n ot reflec t red u ce d in h ib itio n , b u t in ste a d m ay be d ue to a red u ce d a bility to re vie w rec e nt p e rce p tu a l in p u ts. T his p o ssibility is p artic ula rly relev a n t to on e th e o ry o f sc h iz o p hr en ia (H em sley , 1 9 8 7, 19 9 4 ), w h ic h p ro po se s th a t a pe rc ep tu al in te g ration de ficit m ay u n d erlie som e o f the sy m pto m s tha t pa tie n ts e xp e rie n ce . O u r n e w e x pe rim e n ta l te ch n iq u e s (M illik en e t al., 1 99 4 ; T ipp e r, W ea v er, & M illik en , 19 9 5 ), th at a re d esig n e d to p rev e nt re vie w p roc e sse s c on tribu ting to ne g ativ e p rim ing e ffe cts, w ill re ve a l w h eth er it is a failure o f inh ib ition , rath er th a n pe rce p tua l rev iew , tha t u nd e rlie s red u c ed n eg a tive p rim in g in sc hiz oty p al ind iv idu a ls.
E X PE R IM E N T In div id ua ls w ith h ig h an d lo w sc h iz o ty pa l traits w e re co m p are d u sing a sp atial n eg a tive prim in g ta sk in w h ic h th e y w e re re q uire d to selec t an d lo c a te th e la rge r o f tw o circ le s p re sen ted o n ea ch d isp lay (T ip p e r et a l., 1 99 5 ) (se e F ig . 1 ). A
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Illu s tra ti o n o f th e a rr o w m a rk e rs a n d ex p e rim e n t a l c o n d it io n s . T h e t ar g e t w a s d e fin ed as th e
la rg er o f th e tw o c irc l e s. T h e p rim e ta rg e t w a s a lw a y s s iz e 3 (w ith si z e 2 d i s tra c to r) an d t h e p ro b e ta rg et w a s al w a y s si z e 2 ( w i th s i ze 1 d is tr ac t o r) . O n i g n o re d re p e ti tio n tri a ls , th e p ro b e ta rg e t a p p e ar ed in th e s a m e lo c a t io n a s t h e id e n tic al p r im e d is t ra c t o r. T h e n u m b e rs w e re n o t a c tu a lly p re s e n t e d , t h e y ar e d is p la y e d fo r d e s c rip tiv e p u rp o s e s o n l y .
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n eg a tive prim in g effec t of ±2 6 m illisec o nd s (c on trol 4 58 m se c; ig n o red rep e tition 4 8 4m se c) ha s be e n re po rted fo r y ou n g h e althy v olu nte ers o n this ta sk u sin g the sa m e -size d stim u li (T ip p e r et a l., 19 9 5 ). A s th e p rim e d istra c tor a n d th e p ro be targ e t are id en tic al on ig n ore d rep e titio n trials, th e n eg a tiv e p rim in g o b tain ed is a ssum e d to re flec t th e e xte nt to w h ic h th e distrac to r rep rese n tation h as b e en 1 in hib ite d d u rin g sele c tio n. A sig n ific a nt asso c ia tion b etw ee n sch izo ty py a nd n eg a tive p rim in g w o uld in d ic a te th at sch izo ty p al pe rso na lity tra its are re la ted to th e e xte n t to w h ich d istra c to r in h ib ition is utilise d in sele ctio n. S ch iz o ty p y d iffe re nc e s w e re m e a sure d u sin g the rec en tly d ev e lo pe d O x fo rd ± L iv e rp oo l In v en to ry of F e eling s a nd E xp e rie n c es (O L IF E ), w hic h y ield s fou r r el a tiv e ly in d e p e n d e n t s c h iz o ty p y m e a s u re s fro m a 1 5 9 - ite m s e lf-r e p o rt q u estio nn a ire (M a son , C larid ge , & Jac k so n , 1 9 9 5 ). S u b je c ts w ere se lec ted on th e b a sis of th eir ``U nu su a l E x pe rie n c e’ ’ sc ale sco re w h ic h co n ta in s pe rce p tu a l, h allu cin a to ry , a nd m a gic al thin k ing item s an d is d esc rib e d as ``c on sisten t w ith `p ositiv e’ sy m pto m s of psy c ho sis’ ’ (M a son e t a l., 1 9 9 5). T he U n u su al E xp e rie n c e (U N E X ) sca le w a s u se d b ec a use it w a s th e m o st c lo se ly re late d to C la rid g e’ s S T A (C la ridg e & B rok s, 1 98 4 ) m e asu re in b o th th e O L IF E d ev e lo pm en t sam p le (M a son e t a l., 1 9 9 5) a n d in th e sam p le (N = 2 13 ) from w h ic h th e p re se nt g rou p s w e re rec ru ite d (Ja ck so n , p erso n al c om m u n ica tio n ). T he S T A h as b ee n use d in a lm o st e v ery p rev iou s stu dy in w h ich a n a sso cia tio n be tw e e n sc h iz o ty py a nd n eg a tive p rim in g ha s b e en rep o rte d , an d it a pp e ars to c a ptu re the re lev a nt p ers on a lity in fo rm atio n. G iv e n th at inh ib itio n-b a sed the o rie s o f sc h iz o p hre n ia (e .g . M c G h ie & C h ap m an , 1 96 1 ) link atte n tio n a l de ficits to p ositiv e ra the r th an n eg a tive sy m p to m s, a h ig h ly relate d, b u t m o re sp e cific a lly p ositiv e sy m p to m sc ale w as co n sid e red a pp ro p ria te. E v id en ce fo r o ur a ssu m p tion th at p o sitive sy m pto m sc hiz o ty p y tra its a re the m o st lik e ly to re la te to va ria tion in n e g ativ e p rim in g w a s also re c en tly re po rte d b y W illiam s (19 9 5 ).
M E TH O D S ub jects T w e n ty -n in e sub je cts w ith hig h U n u sua l E x pe rie n ce (U N E X ) sco re s a nd 28 su b jec ts w ith lo w U n u su al E xp e rie nc e sco re s w e re re c ru ited from a su b sa m p le o f 17 6 sub jec ts w h o ha d co m p le te d th e O L IF E a s p art of an o the r un rela ted stu d y. T h e se le c tio n su b je cts w e re 35 ye a rs of ag e o r le ss a n d h ad a L ie sc or e 1
A v a ri et y o f d i ff e re n t ta s k p ro c e d u re s h a v e b e e n in v e s ti g a te d . F o r e x a m p le , i n T i p p e r e t a l.
(1 9 9 5 ), m a rk e rs i n th e d i sp la y p ro v i d e d a b a c k g ro u n d c o n te x t a g a i n s t w h i c h th e s ti m u l i w er e p e rc ei v e d . T h i s b a c k g ro u n d c o n te x t e n su re d th a t t h e i g n o re d p rim e a n d s u b s e q u e n t p ro b e w er e p e rc ei v e d a s th e s a m e s i ze , w h i c h i n c re a s e d t h e p e rc e p t u a l s im i la rit y o f t h e s e s tim u li. W e d id n o t u se s u ch p ro c e d u re s h e re b ec a u s e t h e c o n te x t m a rk e rs c o n s id e ra b ly in c re a s e th e c o m p le x i ty o f th e d is p la y
and
w o u ld re d u c e th e p ro b a b ili ty o f s e v e re ly im p a i re d g ro u p s ( e .g . p a tie n t s w ith
s c h i z o p h r en ia , A lz h e im e r’ s D is e a s e , e tc .) c o m p le t in g th e t as k e a si ly . H o w e v er , t h e p at te rn o f n e g a ti v e p ri m in g ef f ec t s o b ta i n e d u si n g t h e c o n te x t m a rk e rs a re t h e sa m e a s th o se o b ta in e d w ith th e ta s k re p o rte d h e re .
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(E y se nc k & E y se nc k , 1 9 75 ) o f 9 or less. In d ivid u als w ere in v ite d to pa rtic ipa te if th e y w e re am o ng th e 6 0 hig he st U N E X sc o re rs or the 6 0 lo w e st U N E X sco re rs in the sam p le. T h e vo lun te ers w er e stu de n ts an d sta ff at th e U n ive rsity o f W a les, B a n go r. T h ere w e re 9 m ale p artic ipa n ts in ea ch U N E X gro u p . T h e h ig h sco ring sa m p le ha d a m e an U N E X sc o re o f 1 9 .8 (S D = 4 .0 3, ran g e 15 ±2 9) , a m e an a ge o f 2 1.5 ye a rs (S D = 4 .0 ), an d a m ea n L ie sc o re o f 4 .0 (SD = 2.6 ). T h e lo w sco rin g sa m p le ha d a m e a n U N E X sc ore of 2 .9 (S D = 1.7 3 ra ng e 0 ±5 ) a n d a m e an ag e o f 2 2.9 ye a rs (S D = 3 .8 ), a nd a m ea n sco re o f 4.3 (S D = 2 .9 ). A ll su b je c ts h a d n o rm al o r co rrec ted -to-n o rm a l vision a nd n o rm a l c o lo u r vision . S u b jec ts w e re p a id fo r th e ir p artic ip a tio n.
Ap p ara tu s an d S tim uli T h e ex p er im en t w as c a rrie d ou t o n a V ig le n 4 86 /3 3 m icro c om p ute r w ith a S V G A co lou r m o nito r. T h e ap p ro xim a te v ie w in g d istan c e w a s 70 ce ntim e tre s. A ll stim u li w e re p re se n te d in V G A m e d iu m re s o lu tio n g r a p h ic s m o d e . R e sp on se s w e re m ad e w ith a K raft K C 30 jo y stic k in te rfa ce d to th e co m p ute r via a stan d ard g am e p ort. R e ac tio n tim e s w ere c o m p u ted usin g th e ro u tin e s pu b lish e d by B ov e n s an d B ry sb ae rt (1 9 9 0). T h e stim u li w e re so lid d a rk g re y c irc les of th re e differe n t siz es (d es crib ed a s siz es 1 , 2 , a nd 3 ). A t a v iew in g d ista n c e o f a bo u t 70 c m , th e d ia m e te rs o f th e circle s (in de g re e s of visu a l a ng le ) w ere 0.4 9 d eg re es fo r siz e 1 , 0.7 4 d eg re es fo r siz e 2, an d 0 .9 8 d eg ree s fo r siz e 3. T h e circ le s ap p e are d on a lig h t g re y ba c kg ro u n d in tw o of fou r po ssible lo c atio n s, w ith fo u r da rk g re y arro w s (p o intin g u p , d o w n , le ft, a n d rig ht fro m th e c e ntre o f the scre en ) u sed to m a rk th e fo u r p ossib le lo ca tio n s. T h e d ista n ce fro m th e tip o f th e le ft p o in ting a rrow to th e tip o f th e rig h t po in tin g a rro w a n d from th e tip o f the u p w a rd po intin g arro w to th e tip o f th e d o w n w a rd po in tin g a rrow w as 3 .0 3 d e g re e s. E ac h c irc le w as ce n tre d on a po int 1 .0 6 de g ree s from th e tip of its arro w m ark e r.
Proced u re S ub je cts w e re to ld tha t d urin g e ac h tria l, th ey w o u ld see tw o c irc les on th e scre en an d tha t o n e c irc le w ou ld b e la rge r th an th e o th e r. T h e su b je c t’ s ta sk w a s to in d ic a te th e loc a tio n o f th e la rge r c irc le a s q uic k ly as po ssib le b y m ak in g a sp a tia lly c o m p a tib le m o v e m e n t o f th e jo y stic k (U P , D O W N , L E F T , o r R IG H T ). E a ch p a ir of trials b eg a n w ith a v isua l p rom p t fo r th e su bje cts to p ress th e sta rt ke y . Im m e dia te ly after th e sta rt k ey w a s p re sse d, th e fo ur a rrow m ark er s ap p ea re d o n th e sc ree n . T h e a rrow s rem ain ed v isib le th ro u gh o u t ea ch tria l: 15 0 0 m se c a fte r the sta rt ke y h ad be en p resse d, th e first o f tw o d isp lay s (th e prim e ) w as pre se nte d. O n e c irc le w a s d ispla y ed at th e tip of e a ch o f tw o a rro w s. In th e p rim e d isp la y , the larg er (targ e t) circ le w as a lw a y s a size 3 c ircle an d th e sm a lle r circle w a s alw a ys siz e 2 .
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T h e p rim e d isp lay re m a ine d o n the sc ree n u ntil a re sp o n se w a s m a d e (i.e. the su b jec t m o v e d th e jo y stic k u p , d ow n , le ft, o r righ t). A u ditory fee d ba c k allo w ed 2 th e su b je ct to d istin g u ish b e tw e en c orre ct resp o n ses a n d e rrors. F o llo w in g the re sp on se , the disp lay v an ish ed , lea v ing on ly th e arro w s o n th e sc ree n fo r 3 5 7m se c. T h e p ro b e d isp lay w a s th e n p rese n te d . A s in th e p rim e , th ere w e re tw o c irc les, o n e larg er th a n the oth er. T he la rg e r c irc le w as alw ay s size 2 a n d the sm aller circle w as a lw a ys size 1 . T h e p ro be disp la y c irc les also re m a in e d o n the sc ree n un til th e su b je c t m ad e a jo ystick re spo n se. T h e scre e n w as th e n c lea red a nd th e p ro m p t to p re ss the start ke y rea p pe a red .
D esig n T he p ro b e trials c o nta in e d a w ith in -su b jec t prim in g tria ls fac tor; trials w e re d ivid ed b e tw e e n co n tro l a nd ig no re d re p e titio n . O n c o ntro l trials, th e tw o p ro be c irc les a pp e a re d in th e tw o lo c atio ns th at ha d n ot be e n o c cu p ie d by eith er c irc le o n the pre vio u s p rim e tria l. O n ig n ore d rep e tition trials, the p ro b e ta rge t (size 2 c irc le) alw a ys a pp e a re d in th e lo c atio n tha t h ad b ee n o c cu p ie d b y th e ide n tic al p r im e d istr a c to r. T h e re w e re 1 8 in itia l p ra ct ic e tria ls , f o llo w e d b y 9 0 e xp e rim e nta l tria ls. In a n a tte m p t to co n ce a l th e n eg a tiv e prim in g m an ip ula tio n , o n ly o n e-th ird o f the e xp e rim en tal trials w ere ign o re d re p etitio n trials. T rials w e re p rese n te d in b lo c k s o f n in e , an d w ith in e ac h blo ck , th e th ree ign o red re pe titio n tria ls w e re alloc a ted ra n d om ly . T h e lo c a tio n s u sed in the prim e d isp la y w e re se lec ted a t ra nd o m o n all tria ls; th e lo ca tio n s o f th e p ro b e stim u li w e re d ete rm in ed b y th e tria l ty p e .
R ES U LT S P ro b e D isp lay R Ts an d Erro rs M ea n o f m ed ia n R T s an d e rror p e rc en tag e s fo r the tw o U N E X g ro u p s a re sh ow n in F igs 2 A an d 2 B . T h ere w er e la rge r n e ga tiv e p rim ing effec ts o n R T an d e rro rs in th e L o w U N E X g ro up th a n in th e H ig h U N E X g ro up . T h e m ea n n e g ativ e p rim in g R T e ffec ts, ob ta in e d b y su b tra ctin g the m ea n ig no re d re pe tition R T fro m th e m ea n co n tro l R T , w e re ±2 7.4 m se c for the L o w U N E X g rou p (c om p ara b le to th e ±2 6m se c e ffec t o b tain ed b y T ip pe r et a l., 1 9 95 ) a nd ±1 4.4 m se c fo r the H ig h U N E X gro u p. T h e m e a n n e ga tive p rim in g e rro r p erc e n ta g e effe cts, ob tain e d in th e sa m e w ay , w ere ±0 .9 5 fo r the L o w U N E X g rou p a n d ±0 .5 7 fo r the H ig h U N E X g rou p . T h e m ed ia n R T s w ere a n aly sed in a 2 ´ 2 m ixe d a n aly sis o f v a ria n c e (A N O V A ). T h e b etw e en -su bje cts fa cto r w as U N E X g rou p a nd th e w ith in 2
A n er ro r w a s re co rd e d if n o re s p o n s e w a s m ad e w ith in 3 .5 s e c o n d s o f th e c irc l e p re s e n t at io n , o r if
th e d ire c ti o n o f t h e j o y s tic k m o v e m e n t d e v ia t e d b y m o re th a n 4 5 d eg re e s (to e it h e r s i d e ) f ro m th e c o rr e c t d i re c t io n .
Downloaded by [Adams State University] at 11:05 10 December 2014 FIG . 2 (A an d B ).
M e a n s o f m e d ia n re s p o n s e t im e s (R T s ) a n d e rr o r p e rc e n ta g e s fo r th e h ig h a n d
lo w U N E X s u b j e ct g ro u p s .
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su b jec ts fac tor w as p rim ing co n d itio n (co n tro l vs. ig no re d rep e titio n). T he a na ly sis re v e aled a sign ifica n t p rim in g c on d itio n m a in e ffec t [F (1 ,5 5 ) = 9 0 .3 , M S E = 13 7 .6 , P < .0 0 0 1] an d a sig n ifica n t p rim in g c o nd itio n ´ U N E X g rou p in te ra ction [F (1 ,5 5 ) = 8 .8 , M SE = 1 3 7 .6 , P < .0 0 5]. S e p ara te o ne -w ay A N O V A s re ve a le d sig n ific an t ne g ativ e p rim in g in the R T da ta o f bo th th e H igh U N E X g rou p [F (1 ,2 8 ) = 2 9 .6 , M S E = 1 01 .3 , P < .0 00 1 ] an d the L o w U N E X g rou p 3 [F (1 ,2 7 ) = 5 9 .9 , M S E = 1 7 5.3 , P < .0 0 01 ]. T h e m e d ia n erro r p e rce n ta g es w e re a lso su b m itte d to a 2 ´ 2 A N O V A , w h ic h re v e a le d a n o v e r a l l n e g a t iv e p ri m i n g e f fe c t i n th e e r r o r r a t e s [F (1 ,5 5 ) = 4 .5 , M S E = 3 .6 , P = .0 4 ] b ut n o inte rac tio n b etw ee n n e ga tive p rim ing a nd U N E X g ro up .
C O N C L U S IO N S T he p re sen t stud y h as fo c u sed o n the in hib itio n m e ch a n ism b y rem o vin g a ny p e rc e p t u a l m is m a tc h b e tw e e n p ri m e d is tra c to r a n d p ro b e ta rg e t in th e e xp e rim e nta l ta sk . T h e resu lts a re c lea r: N e g a tiv e prim in g e ffe c ts are sm alle r in th e hig h U N E X su b jec ts, e ve n w he n the ign o red p rim e a n d su b se q ue n t p ro be a re id e n tic al o b jec ts, su p p or tin g th e c laim o f o th e rs (e .g . B e ec h e t a l., 19 9 1 , 1 9 89 a ,b ) th at sc h izo typ a l su bje cts a re le ss a ble to in h ib it d istra ctin g in fo rm a tio n . In ad d itio n , th is w o rk h as de m o n strate d th a t sc h iz o typ y d iffe re nc es in in hib itio n ca n be d ete cted w ith a n ew ty pe o f n e g ativ e p rim in g task . A ll p re v io u s stu d ie s o f ne g ativ e p rim ing in sc hiz o ty p al g rou p s h a ve re qu ire d su b jec ts to id en tify a stim u lus, su ch a s na m in g a co lo ur, w o rd , o r p ic ture . T h e pre sen t e xp e rim e nt h a s d e m o n stra ted th at in d iv id ua l d iffe ren c e s in th e u se of in h ibition d u rin g sele c tio n a ffe ct low e r le v e l lo ca lisatio n re sp on se s as w e ll a s h igh e r le v el se m a n tic pro c esse s. T h e se re su lts are clea rly c o nsisten t w ith th e e xiste nc e o f an inh ib ito ry d e fic it in sch izo p h ren ia an d re la ted state s. T h e R T d ata c ollec ted h e re in dic a te tha t the lo w e r lev e ls o f inh ibitio n o b serv e d in th e sch izo ty pa l gro u p do n o t slo w o r im p a ir ta sk p e rform an c e, w h ic h m a y m e an tha t sch izo ty p al ind iv idu a ls a c hie ve e ffic ie n t targ et se lec tio n v ia o th e r e x cita to ry p ro c e sses. It is assu m e d h ere th at in div idu a ls w ith sc hiz oty p a l p e rson a lities are m o re lik e ly to d ev e lo p p sy ch o tic d iso rd e rs th a n in d iv id u als w h o are n ot sc h iz o typ a l, a nd th at the y a lso sh a re so m e c ha ra cte ristics (in clu d in g co g n itiv e p ro ce ssin g a ttribu te s) w ith pe o ple w ho h a ve d ev e lo pe d p syc h o ses (e .g . C la rid g e , 1 9 85 ). It m ay b e the n th at m ost p e op le w h o d e v elo p p sy c h o tic sy m p to m s alre a d y h av e a re la tiv e ly la rg e n u m b e r o f 3
A lt h o u g h t h e s e d a ta d e m o n s tra t e t h a t h ig h U N E X s u b je c ts u t ili se le s s i n h ib it io n th a n lo w U N E X
s u b je c t s, i t is re c o g n is e d th a t th is a s so c ia ti o n m ay n o t b e u n iq u e to U n u s u a l E x p e rie n ce s s ca l e a n d c o u l d re fl ec t a c l o s e r as s o ci a tio n b e tw e e n i n h ib iti o n a n d an o th er c o rr e la te d m ea s u re o f s c h i z o ty p y . U n fo rt u n a te ly , h o w e v e r, t h e s e le c ti o n o f e x tre m e U N E X g ro u p s in t h e p re s e n t s t u d y m e a n s th a t U N E X a n d t h e o th e r O L IF E s c a le s (w h ic h h a d c o n ti n u o u s d i s trib u t io n s in th e p re se n t s a m p l e) ca n n o t b e v a li d l y c o m p a re d a s c o rr e la te s o f th e in h i b i tio n m e a s u re .
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sym p tom -re late d p e rson a lity tra its. It is p e rh a p s o nly if an d w he n sc hiz op h re nia de v elo p s in su ch ind iv id u a ls, an d w h e n oth er (n orm ally co m p e nsa to ry) c og n itiv e pro c esse s b e g in to d e te rio ra te , th a t th e re du c e d in h ib ition see n in he a lth y sch izo ty pa l su bje cts a ssum es a n y fu n ctio na l sig n ific an c e . Ind iv id u a ls w h o de v elo p c lin ic a l sym p tom s m ay th en su ffe r th e e ffec ts of re d u ce d c og n itiv e in h ib ition , w hic h is e x po se d a n d co m po u n d ed by o th er co g nitiv e de fic its, a n d ex p erie nc e th e in fo rm a tio n o v e rlo a d th at p atien ts ha v e de sc rib e d. It is a lso im p o rtan t to n o te tha t th is re se arc h ca n sa y little ab o ut in div idu a l differe n ce s in th e p erc ep tu a l rev iew p ro ce ss; th e de tec tio n o f re du c ed in hib itio n in sc hiz oty p a l p e rson a lities d o es no t ex c lu d e th e po ssib ility th at th e o p era tio n o f pe rc ep tua l re vie w p ro c e sses is also asso c iate d w ith sc hiz oty p y . A de fic it in th e ca p ac ity to lin k p e rce p tua l e v en ts a c ro ss tim e c ou ld b e re lev a nt to th e sy m p to m s of sc hiz op h re n ia an d to sc h iz o ty p y . S c hiz oty p y d iffere n ce s in n eg a tiv e p rim in g ta sk s th a t inv o lve p erc e ptu al rev iew w ill th e re fo re b e in ve stig a ted in fu tu re re se arc h . M a n u s c ri p t re c e i v e d 1 2 J u n e 1 9 9 6 R e v i se d m a n u s cr i p t r ec e iv e d 2 9 O c t o b e r 1 9 9 6
R EFE R E N C ES B a ru c h , J ., H e m s le y , D ., & G ra y , J .A . (1 9 8 8 a ). L at e n t in h ib i ti o n a n d `p s y c h o t ic -p ro n e n e s s’ in n o rm a l su b je c ts . P e r s o n a lit y a n d In d iv i d u a l D i ffe r e n ce s , 9 , 7 7 7 ±7 8 4 . B a ru c h , J ., H e m s le y , D ., & G ra y , J .A . (1 9 8 8 b ). D iffe re n tia l p e rf o rm a n c e o f ac u te a n d c h r o n ic s c h iz o p h re n ic s in a la t en t i n h ib it io n ta s k . J o u r n a l o f N er v o u s a n d M en ta l D is e a se s , 1 7 6 , 5 9 8 ± 6 0 6. B e e ch , A ., B a y lis , G ., S m it h s o n , P ., & C l ar i d g e , G . (1 9 8 9 a ). In d iv id u a l d i ff e re n c e s in s c h iz o ty p y a s r ef l e c te d in m e a s u re s o f c o g n it iv e in h ib iti o n . B r i tis h J o u r n a l o f P s y ch o lo g y , 2 8 , 1 1 7 ±1 2 9 . B e e ch , A ., & C la rid g e , G . (1 9 8 7 ) . In d i v i d u a l d i ff e re n c e s in n e g a tiv e p rim i n g : R e la t io n s w i th s c h iz o ty p a l p er so n al ity tra it s. B r iti s h J o u r n a l o f P sy c h o l o g y , 7 8 , 3 4 9 ±3 5 6 . B e e ch , A ., M c M a n u s , D ., B a y l is , G ., T i p p e r, S .P ., & A g a r, K . (1 9 9 1 ). In d iv id u a l d iffe re n c e s in c o g n i tiv e p r o c e s s es : T o w a rd s a n e x p l a n a ti o n o f s c h iz o p h re n ic s y m p t o m a t o lo g y . B r iti s h J o u rn a l o f P s yc h o l o g y , 8 2 , 4 1 7 ±4 2 6 . B e e ch , A ., P o w e l l, T ., M cW il lia m , J ., & C la rid g e, G . (1 9 8 9 b ). E v id en c e o f re d u c e d `c o g n iti v e i n h ib it io n ’ in s c h i zo p h re n i a. B r it is h J o u r n a l o f P s yc h o lo g y, 2 8 , 1 0 9 ±1 1 6 . B le u le r, E . (1 9 5 0 ). D e m e n tia P r a e c o x o f th e g r o u p o f s c h iz o p h r e n i a s . N e w Y o r k : In t er n a ti o n a l U n iv e rs iti e s P re s s . (O rig in a l w o rk p u b lis h e d 1 9 1 1 ) B o v e n s , N ., & B ry s b a e rt, M . (1 9 9 0 ). IB M P C /X T / A T a n d P S / 2 T u rb o P a s c a l tim i n g w it h e x te n d ed r es o lu tio n . B e h a v io r R e s e a r c h M e th o d s , In st ru m e n t s a n d C o m p u te rs , 2 2 , 3 3 2 ±3 3 4 . B ra ff , D .L ., H ea t o n , R .K ., K u c k , J ., C u l lu m , M o ra n v i lle , J., G ra n t, I. , & Z is o o k , S . (1 9 9 1 ). T h e g e n er al iz e d p at te rn o f n eu ro p s y c h o l o g ic a l d ef ic its in o u tp a tie n ts w i th c h ro n i c s c h i z o p h r en ia w i th h e te ro g e n e o u s W is c o n s in C a rd S o rti n g T e s t re s u lts . A r c h iv e s o f G e n e r a l P sy c h ia try , 4 8 , 8 9 1 ± 8 9 8. B u l le n , J .G ., & H em s le y , D .R . (1 9 8 4 ). P s y c h o tic is m an d v is u a l re c o g n i tio n th re s h o ld s . P e rs o n a li ty a n d In d i v id u a l D iff e re n c e s, 6 , 7 3 5 ±7 3 9 . C h a p m a n , L ., C h a p m an , J .P ., & M il le r, G .A . ( 1 9 6 4 ). A th e o ry o f v e rb a l b e h a v io r i n s c h i zo p h re n ia . P r o g r e ss in E x p er i m e n ta l P e r s o n a lit y R e s ea r c h , 1 , 4 9 ±7 7 . C la rid g e, G .S . (1 9 8 5 ). O r ig i n s o f m e n t a l i lln e s s . O x fo rd : B la c k w e ll .
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C l ar id g e , G .S . (1 9 8 7 ). `T h e s c h i z o p h r en ia a s n e rv o u s t y p e s’ re v is i te d . B ri tis h J o u r n a l o f P s y c h i a t ry , 1 5 1 , 7 3 5 ±7 4 3 . C l a r i d g e , G .S .,
&
B ro k s , P . ( 1 9 8 4 ) . S c h i z o t y p y
and
h e m i s p h e re
f u n c t i o n : I. T h e o r e t i c a l
c o n s id e ra tio n s a n d t h e m e a s u re m e n t o f s c h iz o t y p y . P e r s o n a l ity a n d In d iv i d u a l D i ffe r e n ce s , 5 , 6 3 3 ±6 4 8 . C l ar id g e , G .S ., C la rk , K .H ., & B e ec h , A .R . (1 9 9 2 ). L at e ra liz a ti o n o f th e `n e g at iv e p ri m i n g ’ e ff e c t: R e la t io n s h ip s w ith s c h i zo ty p y a n d w ith g e n d er . B r iti s h J o u r n a l o f P sy c h o lo g y , 8 3 , 1 3 ±2 3 . C o rn b l at t, B .A ., L e n z e n w e g e r, M .F ., & E rl e n m e y e r- K im l in g , L . (1 9 8 9 ). T h e C o n tin u o u s P e rf o rm a n c e T e st , Id e n tic a l P a irs V e rs io n II : C o n tra s tin g a tte n ti o n p ro fi le s in s c h iz o p h re n ic a n d d ep re s s ed p a t ie n t s. P s y c h ia tr y R e se a r ch , 2 9 , 6 5 ±8 5 . D e l a C a s a , L .G ., R u iz , G ., & L u b o w , R .E . (1 9 9 3 ). L a te n t in h ib it io n a n d re c a ll /re c o g n it io n o f
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irre l e v a n t s tim u li as a fu n c tio n o f p re -e x p o s u re d u ra tio n i n h i g h a n d lo w p sy c h o ti c -p ro n e n o rm a l s u b je c ts . B r iti sh J o u r n a l o f P s y c h o lo g y , 8 4 , 1 1 9 ±1 3 2 . E y s e n c k , H .J ., & E y s e n c k , S .B .G . (1 9 7 5 ). M a n u a l o f E y s e n ck p e r s o n a lit y q u e s ti o n n a ir e. L o n d o n : H o d d e r & S to u g h t o n . F r ith , C .D . (1 9 7 9 ). C o n s c io u s n e s s , in fo r m a ti o n p ro c es s in g a n d s ch iz o p h re n ia . B ri tis h J o u r n a l o f P s y c h ia t r y, 1 3 4 , 2 2 5 ±2 3 5 . H e m s le y , D .R . (1 9 8 7 ). A n e x p er i m e n ta l p s y c h o lo g i c a l m o d e l fo r s c h i z o p h r en ia . In H . H a fn e r, W .F . G a tta z , & W . J a n z a rik (E d s .) , S e a r c h f o r th e c a u s e s o f s c h i z o p h r e n ia . H e id e lb e rg : S p ri n g e r. H e m s le y , D .R . (1 9 9 4 ). P e rc ep tu a l a n d co g n i tiv e a b n o rm a lit ie s a s th e b a s es fo r sc h iz o p h re n ic s y m p to m s . In A .S . D a v id & J .C . C u tti n g (E d s .) , T h e n eu r o p s y c h o l o g y o f s c h i z o p h r e n ia . H o v e , U K : L a w re n c e E rlb a u m A ss o c ia te s L td . K a h n e m a n , D ., T r ei s m a n , A ., & G ib b s , B .J . (1 9 9 2 ). T h e re v ie w in g o f o b je c t fil e s: o b j e ct -s p e c ifi c in te g ra tio n o f in fo rm at io n . C o g n it iv e P s y c h o lo g y , 2 4 , 1 7 5 ±2 1 9 . L ap la n te , L ., E v e re tt, J., & T h o m a s , J . (1 9 9 2 ). In h ib it io n t h ro u g h n e g a tiv e p r im in g w i th S t ro o p s tim u li i n sc h iz o p h re n ia . B r iti sh J o u r n a l o f C li n i c a l P sy c h o l o g y, 3 1 , 3 0 7 ±3 2 6 . L en z e n w e g er , M .F ., C o rn b la t te, B .A ., & P u t n i ck , M . (1 9 9 2 ). S c h i zo ty p y a n d su s ta in e d a tt e n t io n . J o u r n a l o f A b n o r m a l P s y c h o l o g y , 1 0 0 , 8 4 ±8 9 . L en z e n w e g er , M .F ., & K o rfin e , L . (1 9 9 4 ) . P e rc e p tu a l a b er ra tio n s , s c h iz o t y p y an d th e W is c o n s in C a rd S o rtin g T a sk . S c h i zo p h r e n ia B u ll et in , 2 0 , 3 4 5 ±3 5 7 . M as o n , O ., C la ri d g e, G .S ., & J a c k s o n , M . (1 9 9 5 ). N e w s c a le s fo r th e a s s es s m e n t o f s c h i z o ty p y . P e r s o n a lit y a n d In d iv i d u a l D iff e re n c e s , 1 8 , 7 ±1 3 . M cG h ie , A ., & C h a p m a n , J. (1 9 6 1 ). D i so rd e rs o f a tt e n t io n an d p e rc ep ti o n i n e a rly s c h iz o p h re n ia . B r i tis h Jo u rn a l o f M e d ic a l P s y c h o lo g y , 3 4 , 1 0 3 ±1 1 5 . M ill ik en , B ., T ip p e r, S .P ., & W e a v e r, B . (1 9 9 4 ). N e g a ti v e p ri m in g in a s p a ti a l lo c al iz a tio n t a sk : F e a tu re m i s m at c h i n g a n d d is tra c to r in h ib it io n . J o u r n a l o f E x p e r im en ta l P s y c h o lo g y : H u m a n P e r c e p t io n a n d P e r fo r m a n c e , 2 0 , 6 2 4 ±6 4 6 . N e i ll , W .T . (1 9 7 7 ) . In h ib i to ry
a nd
fa c il i ta t o ry
p ro c e s s e s in
se le c t iv e
a tt e n ti o n . J o u r n a l o f
E x p e r im e n ta l P sy c h o l o g y : H u m a n P e r c ep ti o n a n d P e rf o r m a n c e , 3 , 4 4 4 ±4 5 0 . O b io ls , J .E ., G ar c i a -D o m in g o , M ., d e T ri n c h e ri a, I., &
D o m e n e c h , E . (1 9 9 3 ). P s y c h o m e tric
s c h i zo ty p y a n d s u s ta in e d a tte n ti o n in y o u n g m a l es . P e r s o n a lity a n d In d iv i d u a l D iff e re n c e s , 1 4 , 3 8 1 ±3 8 4 . P e t e rs, E .R ., P i c k e ri n g , A .D ., &
H e m sl e y , D .R . (1 9 9 4 ). `C o g n iti v e in h i b i tio n ’
and
p o s it iv e
s y m p to m a to lo g y i n s c h i z o t y p y . B r iti sh J o u r n a l o f C li n i c a l P sy c h o l o g y, 3 3 , 3 3 ±4 8 . R o s e n b a u m , G ., S h o re , D .L ., &
C h a p in , K . (1 9 8 8 ). A tt e n t io n d e fic it in s c h i z o p h re n ia a n d
s c h i zo ty p y : M ar k e r v e rs u s s y m p t o m v a ria b le s . Jo u rn a l o f A b n o rm a l P s y c h o l o g y, 9 7 , 4 1 ±4 7 . S p rin g , B .J . (1 9 8 0 ). S h ift o f a tt e n t io n in s ch iz o p h re n ic s , s ib li n g s o f s c h i z o p h re n ic s a n d d e p re s s e d p at ie n ts . J o u r n a l o f N e r v o u s a n d M e n t a l D i se a s e, 1 6 8 , 1 3 3 ±1 4 0 . T ip p e r, S .P . (1 9 8 5 ). T h e n e g a tiv e p ri m in g e ff e c t: In h i b i to ry e ff e c ts o f i g n o re d p ri m e s. Q u a r t er l y J o u r n a l o f E xp e r im e n ta l P s yc h o l o g y, 3 7 A , 5 7 1 ±5 9 0 .
S C H IZ O T YP Y A N D D IS T R A CT O R IN H IB IT IO N
79
T ip p er , S .P ., & B a y l is , G .C . (1 9 8 7 ). In d iv id u al d iffe re n c e s in s e le c ti v e a tte n ti o n : T h e r el a tio n o f p rim i n g an d in te rf e re n c e to c o g n i tiv e f ai lu re . P e r s o n a l ity a n d In d iv id u a l D iffe r e n c e s, 8 , 6 6 7 ±6 7 5 . T ip p er , S .P ., & C ra n st o n , M . (1 9 8 5 ) . S e le c ti v e at te n tio n a n d p rim in g : In h ib it o ry a n d f ac i lit a to r y e ff e c t s o f ig n o re d p rim e s . Q u a r te r ly J o u r n a l o f E xp e r im en ta l P s y c h o l o g y, 3 7 A , 5 9 1 ±6 1 1 . T ip p er , S .P ., W e a v e r, B ., & M il lik e n , B . (1 9 9 5 ). S p a tia l n e g a tiv e p rim in g w ith o u t m i s m at c h i n g : C o m m e n t o n P a rk a n d K a n w is h e r (1 9 9 4 ). J o u r n a l o f E x p e r i m e n ta l P s y c h o lo g y : H u m a n P e r ce p ti o n a n d P e rf o r m a n c e, 2 1 , 1 2 2 0 ±1 2 2 9 . W il k i n s , S ., &
V e n a b le s , P .H . (1 9 9 2 ). D is o rd er o f a t te n t io n in i n d iv id u a ls w ith s c h iz o t y p a l
p e rs o n a li ty . S c h iz o p h re n i a B u l le ti n , 1 8 , 7 1 7 ±7 2 3 . W i ll i am s, L .M . ( 1 9 9 5 ). F u r th e r e v i d e n c e fo r a m u l ti d im e n s i o n a l p e rs o n a li t y
d is p o s it io n
to
s c h iz o p h re n ia i n te rm s o f c o g n it iv e i n h ib it io n . B r it is h Jo u rn a l o f C lin ic a l P sy c h o l o g y, 3 4 ,
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1 9 3 ±2 1 3 .
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