Ergonomics
ISSN: 0014-0139 (Print) 1366-5847 (Online) Journal homepage: http://www.tandfonline.com/loi/terg20
Sleep Loss Effects on Movement Time Leslie Buck To cite this article: Leslie Buck (1975) Sleep Loss Effects on Movement Time, Ergonomics, 18:4, 415-425, DOI: 10.1080/00140137508931475 To link to this article: http://dx.doi.org/10.1080/00140137508931475
Published online: 26 Apr 2007.
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Citing articles: 5 View citing articles
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Date: 06 November 2015, At: 15:31
Sleep Loss Effects o n Movement Time
Downloaded by [NUS National University of Singapore] at 15:31 06 November 2015
Control Systems Laboratory, Nntionnl Rcscnrch Council, Ottnwa K I A OICG, Canada Subjects were tested on a subject-pacod step-trnckirtg task thrce times ovcry r o w hourn under both of two rcgimcs: one in which they slcpt for B:30 hours a t night and one in which they relnaincd nwakc. 12 subjccts were tested fur two days under ench condition, and 8 su.bjccts fur thrce days. Rcnction times fur corrcct reqlonscs increased following sleep loss to no extcnt invcrscly related to sigtlal probability. Movomcnt timcs incrensed following slccp loss to n much greater extent. It is concludctl thnt movement time is a lnoro sensitivc itlrlcx of performance detcriorntioo duc to slcop loss and that moromcnt time and rcnction time reprosent scpnrate processes.
1. Introduction Several years ago Gibhs (1 967) described a test for measuring the effects on l~sj~chomotor t~erformanceof adverse conditions such as alcohdic ini1,airment imcl disturbed sleep. Subsequent research into the itppliciltion of this test has included studies of insulin-induced hypoglycaemia (Fraser et al. 1974) and of deprivation of sleep (Buck and Gibbs 1972). A major point a t issue 11as been whether any of the scores yielded by the test has been sensitive t o the presence of the stress in question. I n the case of sleep deprivation, while earlier studies led t o the formulation of hypotheses relating changes in reaction time and movement time t o extent of sleep loss, inadequate controls precluded definite conclusions. !I?l~eunresolved questions rkzisecl by these studies remain of interest however, since, althougt~ some experimenters have met~sured reaction time following sleep loss using test configurations which eliminate or rcduce response member movements (Lisper and Kjellberg 1952, Williams el nl. 1959), otl~ershave measured only gross total response time or its equivalent (number of rcsponses, or number of delayed responses, per unit time) in tasks such c~sa serial reaction task (Wilkinson 1959) or a n addition task (Loveland and Willii~msI!)(iR) in which movement time appears as an undifferentiated component. Jlemonstration of separate effects on reaction time and movement time would therefore be a new finding. The present paper reports additional, more idequately clcsignecl, experiments dealing with this point. 2. Description of the Task The subject-paced stcp-tracking task conceivecl by Gibbs and used in these experiments is known as the NRC stressulyser. h reverse-linked wheel controls the position of a pursuit pointer in relation to five circumferentially arranged lamp positions (Figure I ) . 'I'lle subject aligns the pointer with the illuminatcd alignment the 1ttmp extinguishes target lamp, and after 200 msec ~n~intcrruptccl and mother lights simultaneously to present the next target. Target alignment was determined in the present experiment by an SDS 920 compuler programmed to digitise the output of a potentiometer linked to the pursuit pointer, and to compare this with stored values representing target centres and
Downloaded by [NUS National University of Singapore] at 15:31 06 November 2015
ttwgct width. T l ~ ccomputer also controlled the sequence of target ])resentstion, i ~ n dtinwd the sncccssive intcrvids betwccn twget presenti~tion,initiation of prnsuit movcment, initiation of movement towards tlie target if i t \\.ere origindly :r\vay from thc target, and initiation of 200 msec uninterr~cptecl idignnicnt. Illhcse non-overlapping periods were tlefincd as reaction time, cwor correction titno i d movement t i ~ n e . Movement time as clefincd here incl~dccltimc spent correcting overshoot \vlmiever tlie first alignment with the h r g c t \\,asi~ltcrruptcdwithin 200 mscc, as well as the periods of such interrupted ; I i g n n e n t s I:n ittlclition to met~suringthcsc times tlic cornputcr recorded t initiated away from instmces of overshoot i ~ n dof cn.or ( p r s ~ t i tnovctnents tllc titrgct).
i g r o I A sul~jcct-pncwlst.op-tnrcking task wit11rovurse control-display relation. Tho subject has nligned tho pursuit. puintcr wit11n tnrgct at. lamp position 4 (riumbered froru left t o righL ncross 1.1~0 disI,lay) by rotuting thu cont,rol wl~colto tho loft of its middlcrnost position. I>iat.nl~coI,otwour~n~ljucenltar got.^ is 41 rnm ancl targot dinmcter is 2.4 znm.
One Iit~nilrctltiwget ; ~ n dpursuit ~novenicntscotiipleted one trial run. !Pa.rgct niovc~ncntswere in t~pparcntlyrandom ordcr, although in fact each of t h c t\vcnty possible tnovelncnts between any position and any one of the other four occllrred five times. This nicnnt t h a t the probabjlitics of left versus right rno\wlnent a t the fivc positions cross thc display were zero: I , 0.25 : 0.75; t of 0.50 : 0.50; 0.75 : 0.26 and 1. : zero. Furthermore, targets lay t ~ distances 1 , 2, 3 or 4 units inter-position interval. :Buck (1972) showed t h a t reaction titncs associ;~tecl with correct responscs varied inversely with directional probitbility, m t l movcment times varied with target distance, as thus defined. !ll:hlc I sho\vs data of the present experiment, collected from subjects when not tlcprivcd of sleep, itnalysed t o demonstrate thesc findings. Iteaction times i~ssocitrtcdwith incorrect responses (errors), and some spurious reaction times of 5 mscc or Icss, wcm cxclr~detlfrom this analysis. 'Illie movement timc data on the othcr Iii~ndinclt~dest h a t for both correct and incorrect responses, since nltho~cglitarget distance was increased by the initial error in movement, the cfYcct on movetncnt time wns only of the order of about 5% itnd niey he rcgi~ldcdns negligible. Tlic actual direction of movement, left or right, also nppcws to I~a\wI)ccn r~nimpoi-tantin respect of both nwnsnres. From thesc findings i t was considered t~ppropriatct o group tlie data of eaoh run so as to
Sleep Loss Effects on ilIoven~entTime
41 7
Downloaded by [NUS National University of Singapore] at 15:31 06 November 2015
compute mean correct reaction times for four levels of directional probability (p),and metm movement times for four levels of target distance (d). The an~tlysisshows further that correct reaction time was not dependent upon the amplitude of the subsequent movement, and that movement time was not dependent on the preceding probability of moving in t h a t direction. The result, is in line with that of Eitts and Peterson (1964)-although their movement time did not include an overshoot correction time component--and like theirs can be adduced as support for the view t h a t the two processes represented by reaction time and movement time are relatively independent. Tablo 1. BIoan correct rcaction times am1 mean lnovo~nenttimcu ( ~ n e cfor ) each of t,wcnty possiblo target movcmcnts. Ench entry is the Incan of tho nlenn valucs for 600 trinl runs (15 runs on Day 1 under both conditions for 20 subjects), each of which v n s in turn the mean of 111' t o five datn for that movement. In tho case of correct reection times fewer Lhan five data wcro nvnilahln for avernging whenever incurrect responses wore made, and in some cascs none was nvnilablo so that the entrics were based on fewer than 600 run mcnw, ns indicntcd in pnrenthcaos. ltaliciserl figures aro either signal probability val~tcsor tnrgct distnncc vnlucs, as nppropriate. Starting positiion
A.
Correct reaction Lirucs Tnrgct pouit,ion
13. 3Iove1ncnt Limos Target positicrn 3 850
3 !)I8
I
2
0
I 707 1
I 700
"
I
1042 .3
")
HI!?
909
,
4
I074 3 975
!I25 0
883 I
3. Experimental Design We cwriecl out two experiments each occupying two weekends. Ihperimcnt I. used 1 2 subjects and lasted two days and one intervenit~gnight; Experiment 2 used eight other subjects and lasted three days and two intervening nights. I n both experitnents paid subjects ( 1 8-22 yr males) followed a Control Condition during which they slept 6:30 hr a t night, and a n IEsperimentd Condition in which they remained awake. They followed the two conditions on successive weekends, half in each order (thiit is, condition order was confounded \vit,h indivic1u;~ldifferences between subjects). Once every four hours each subject performed three trial runs on the stressalyser lasting 2-3 min per run, making, with rest pauses, about 12 min per session. Subjects were tested one a t a time ; ~ 1.5 t mi11 intervals, ~necliantimes of testing for the five daily sessions being 0880, 1230, 1630, 2030 and 0030 hr. Subjects pcrfornled twelve training runs with knowledge of rcsults (total time per run) some davs before the first weekend of the exlxximcnt. At the weekends th&c subjects following the IExperimentc~lConclition slcpt at thc 1,aboratory the previous (Thursday) night, while those following the Control
Downloaded by [NUS National University of Singapore] at 15:31 06 November 2015
41.8
Leslie Buck
Cotdition slept t ~ thomc, so tli;at for all subjects tcsts on :Day 1 represcntcd pcrfortniancc following n night. with slcep. Each subject followed tlie same testing scl~ctlr~lc on the two \vcekends. \IrIren tcstecl Ire sat alonc in a cubicle \\.Irere hc \VM \vi~tclrcdthrough closed-circuit television stid instructed tlirougll Ircradpliones. H e received no knomletlgc of results. Subjects following the t tluril& prescribed times which were staggered Control Condition slept t ~night so tlmt ci~clrslept 6:RO hr ancl was aroused 1 : 1 5 lrr before his first test of the tl;ay. :13ctween tcsts subjects diverted themselves with games, radio, television, tnusic, tnc;als, convcrs;ation imcl wi~lking,dl under close supervision. .In experiments of this design subjects become increiasingly deprived of sleep ~ t stlrc cxpcrimcnt procccds from the first test session. :However, during the cor~rscof iany one clay some viariiation of performance between t,ests may be cxpcctctl i ~ s;L consequence of tlrc coninronly observed circaclian rhythm of pcrform;ancc (Hoclrcy mrcl Colqnlroun 1072), :and i t is necessary to distinguish bctwccn this ;and tlrc varii~tionbctwccn di~ys. The effect of sleep loss may be cspcctcd to bc seen in differences in pcrfornrance between Day 1, Day 2, etc., for subjects following tlrc :ISxperirnentnl Condition, corresponding t o the effect of zcru, I , ctc., nights withont slcep, but a further effect might also be apparent in nn intcr;~ctionbetween diay and timc of clay. The design also contains a run within scssion ft~otur,hut prcliminnry i~nialysis(Back 1072) showed t h a t very little v;~ri;~ncc wi~s;attributable t o this, :and scores were iaccorclingly averaged cross runs within scssion. !l.'trr~sfour design factors were consiclerccl-Subjects, Conditions, Ilhys i ~ n d!Cinlcs of day-in addition t o t h e task factors of l'robnbility (2)) in tho case of rcact,ion timc i~ntlDistance (d) in the case of movement ti~nc. 4.
Results
'I'l~ceffect of onc night without slcep \v:as tlre same in Experiments 1 ancl 2: t l ~ c r e\ws no indici~tionthat the clri~ngein pcrformancc following sleep loss \v:as ;~ffectcdby tlrc number of cliays for \vtiich tlre experiment \\ws to run. I n considering tlie effect of one night without slccp (Day I versus Day 2) therefore the data for >all subjects from both experi~nents(a=20) were poolecl, while for two nights wjtliout slccp (Day I versrrs Dkay 3) the data of Experiment 2 (n= 8) wcrc t;alten alonc. 1ICigurc 2 slro\vs mcan correct reaction time scores, i~vcragedfor subjects, for for other 2) values arc the two extreme values of p = 0.26 and p = 1.00. (:l>ati~ given by :Buck and Leonardo 1072 :and 1073.) Tiable 2slro\vs differences bct\vccn days of t h e differences bct\vcen conditions for data. averegccl for subjects ;and t i n ~ c sof day, t h a t is: W,,c - i\'lcc)l,(?or :l) - (%C - ~~CC),), !l.'hcsc sllo~vtlmt the incrcese in correct reaction tinie follo\ving sleep loss v;rrictl inversely with .I, vi~lrlc,and that both thc increase and the interactive r t\vo nights \vitlrorrt sleep t,lran after one. effect of p \vias g ~ w t c after Il.'hcsc findings were tested for statisticd significance usingfivefactor CI.I~U~?/SCS c!f w r i t n m . :In tlrc first case (Ilhy I. versus Day 2) tlie Probability x Conclition x : l h ~ inte~.iwtion y \?iari;ancc was significant using a combined msidual and third ortlcr intert~ctionv;~riamceas the error term !P=7.21, clf = 3,753, P < 0.001.) but t h Condition x :lliay intcriaction vtariancc wns not using the former a s the crrvr term ( . F = 6.47, (If = J,3, 1' > 04.5). 1111 the second case (1Dey 1 versus
Downloaded by [NUS National University of Singapore] at 15:31 06 November 2015
Sleep Loss Bflects on Movmnent Time
n=20
Control Experimental p = 1.00 -
n:8
0
A
o
A
-----
p~0.25
Figure 2. Nenn correct rcact.ion tin~cs. Ench entry is tho mean of thrco trial means for 7r ~ubjcots. JJny 1 results nrc ahown for n = 2 0 a n d 11=8 so a s t o provide appropriate rlntn for nssessiug, respectively, tho c l h t r of ono night a n d two nights without sleep.
'J'nble 2. Jlcun rcnction tin10 scorcs (msec). Jlenns f w onch t&d run were computed by grouping dat,n for cuch target lnovelncnt according to the itnliciscd vnlucs of signul prohahility s h c w i i n Table IA. I n t,hc cnsc < ~d fa t a for T J = 1.00 ndditionnl r u n Incans wcrc computed by gmuping according t o t,he itnlicisetl vniuos of t w g o t dist,nnco shown i n T d h ID. Entries nrc menns f o 11~ s~thjoctsawl 15 clnily trinl runs. Alcans for I h y 1 a r e shc\vn for n = 2 0 a n d n = 8 in ordcr tu provide appropriate c o m p n r i s o ~ ~for - I h y 2 a n d Duy 3 rospcct,ivcly. T h c antrios in parentS~esoaa r e diffcrences bctmecn dnys of the differences betwecn Experimentnl (E) RIKI C o n t ~ o l(C) C:
ISSN: 0014-0139 (Print) 1366-5847 (Online) Journal homepage: http://www.tandfonline.com/loi/terg20
Sleep Loss Effects on Movement Time Leslie Buck To cite this article: Leslie Buck (1975) Sleep Loss Effects on Movement Time, Ergonomics, 18:4, 415-425, DOI: 10.1080/00140137508931475 To link to this article: http://dx.doi.org/10.1080/00140137508931475
Published online: 26 Apr 2007.
Submit your article to this journal
Article views: 14
View related articles
Citing articles: 5 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=terg20 Download by: [NUS National University of Singapore]
Date: 06 November 2015, At: 15:31
Sleep Loss Effects o n Movement Time
Downloaded by [NUS National University of Singapore] at 15:31 06 November 2015
Control Systems Laboratory, Nntionnl Rcscnrch Council, Ottnwa K I A OICG, Canada Subjects were tested on a subject-pacod step-trnckirtg task thrce times ovcry r o w hourn under both of two rcgimcs: one in which they slcpt for B:30 hours a t night and one in which they relnaincd nwakc. 12 subjccts were tested fur two days under ench condition, and 8 su.bjccts fur thrce days. Rcnction times fur corrcct reqlonscs increased following sleep loss to no extcnt invcrscly related to sigtlal probability. Movomcnt timcs incrensed following slccp loss to n much greater extent. It is concludctl thnt movement time is a lnoro sensitivc itlrlcx of performance detcriorntioo duc to slcop loss and that moromcnt time and rcnction time reprosent scpnrate processes.
1. Introduction Several years ago Gibhs (1 967) described a test for measuring the effects on l~sj~chomotor t~erformanceof adverse conditions such as alcohdic ini1,airment imcl disturbed sleep. Subsequent research into the itppliciltion of this test has included studies of insulin-induced hypoglycaemia (Fraser et al. 1974) and of deprivation of sleep (Buck and Gibbs 1972). A major point a t issue 11as been whether any of the scores yielded by the test has been sensitive t o the presence of the stress in question. I n the case of sleep deprivation, while earlier studies led t o the formulation of hypotheses relating changes in reaction time and movement time t o extent of sleep loss, inadequate controls precluded definite conclusions. !I?l~eunresolved questions rkzisecl by these studies remain of interest however, since, althougt~ some experimenters have met~sured reaction time following sleep loss using test configurations which eliminate or rcduce response member movements (Lisper and Kjellberg 1952, Williams el nl. 1959), otl~ershave measured only gross total response time or its equivalent (number of rcsponses, or number of delayed responses, per unit time) in tasks such c~sa serial reaction task (Wilkinson 1959) or a n addition task (Loveland and Willii~msI!)(iR) in which movement time appears as an undifferentiated component. Jlemonstration of separate effects on reaction time and movement time would therefore be a new finding. The present paper reports additional, more idequately clcsignecl, experiments dealing with this point. 2. Description of the Task The subject-paced stcp-tracking task conceivecl by Gibbs and used in these experiments is known as the NRC stressulyser. h reverse-linked wheel controls the position of a pursuit pointer in relation to five circumferentially arranged lamp positions (Figure I ) . 'I'lle subject aligns the pointer with the illuminatcd alignment the 1ttmp extinguishes target lamp, and after 200 msec ~n~intcrruptccl and mother lights simultaneously to present the next target. Target alignment was determined in the present experiment by an SDS 920 compuler programmed to digitise the output of a potentiometer linked to the pursuit pointer, and to compare this with stored values representing target centres and
Downloaded by [NUS National University of Singapore] at 15:31 06 November 2015
ttwgct width. T l ~ ccomputer also controlled the sequence of target ])resentstion, i ~ n dtinwd the sncccssive intcrvids betwccn twget presenti~tion,initiation of prnsuit movcment, initiation of movement towards tlie target if i t \\.ere origindly :r\vay from thc target, and initiation of 200 msec uninterr~cptecl idignnicnt. Illhcse non-overlapping periods were tlefincd as reaction time, cwor correction titno i d movement t i ~ n e . Movement time as clefincd here incl~dccltimc spent correcting overshoot \vlmiever tlie first alignment with the h r g c t \\,asi~ltcrruptcdwithin 200 mscc, as well as the periods of such interrupted ; I i g n n e n t s I:n ittlclition to met~suringthcsc times tlic cornputcr recorded t initiated away from instmces of overshoot i ~ n dof cn.or ( p r s ~ t i tnovctnents tllc titrgct).
i g r o I A sul~jcct-pncwlst.op-tnrcking task wit11rovurse control-display relation. Tho subject has nligned tho pursuit. puintcr wit11n tnrgct at. lamp position 4 (riumbered froru left t o righL ncross 1.1~0 disI,lay) by rotuting thu cont,rol wl~colto tho loft of its middlcrnost position. I>iat.nl~coI,otwour~n~ljucenltar got.^ is 41 rnm ancl targot dinmcter is 2.4 znm.
One Iit~nilrctltiwget ; ~ n dpursuit ~novenicntscotiipleted one trial run. !Pa.rgct niovc~ncntswere in t~pparcntlyrandom ordcr, although in fact each of t h c t\vcnty possible tnovelncnts between any position and any one of the other four occllrred five times. This nicnnt t h a t the probabjlitics of left versus right rno\wlnent a t the fivc positions cross thc display were zero: I , 0.25 : 0.75; t of 0.50 : 0.50; 0.75 : 0.26 and 1. : zero. Furthermore, targets lay t ~ distances 1 , 2, 3 or 4 units inter-position interval. :Buck (1972) showed t h a t reaction titncs associ;~tecl with correct responscs varied inversely with directional probitbility, m t l movcment times varied with target distance, as thus defined. !ll:hlc I sho\vs data of the present experiment, collected from subjects when not tlcprivcd of sleep, itnalysed t o demonstrate thesc findings. Iteaction times i~ssocitrtcdwith incorrect responses (errors), and some spurious reaction times of 5 mscc or Icss, wcm cxclr~detlfrom this analysis. 'Illie movement timc data on the othcr Iii~ndinclt~dest h a t for both correct and incorrect responses, since nltho~cglitarget distance was increased by the initial error in movement, the cfYcct on movetncnt time wns only of the order of about 5% itnd niey he rcgi~ldcdns negligible. Tlic actual direction of movement, left or right, also nppcws to I~a\wI)ccn r~nimpoi-tantin respect of both nwnsnres. From thesc findings i t was considered t~ppropriatct o group tlie data of eaoh run so as to
Sleep Loss Effects on ilIoven~entTime
41 7
Downloaded by [NUS National University of Singapore] at 15:31 06 November 2015
compute mean correct reaction times for four levels of directional probability (p),and metm movement times for four levels of target distance (d). The an~tlysisshows further that correct reaction time was not dependent upon the amplitude of the subsequent movement, and that movement time was not dependent on the preceding probability of moving in t h a t direction. The result, is in line with that of Eitts and Peterson (1964)-although their movement time did not include an overshoot correction time component--and like theirs can be adduced as support for the view t h a t the two processes represented by reaction time and movement time are relatively independent. Tablo 1. BIoan correct rcaction times am1 mean lnovo~nenttimcu ( ~ n e cfor ) each of t,wcnty possiblo target movcmcnts. Ench entry is the Incan of tho nlenn valucs for 600 trinl runs (15 runs on Day 1 under both conditions for 20 subjects), each of which v n s in turn the mean of 111' t o five datn for that movement. In tho case of correct reection times fewer Lhan five data wcro nvnilahln for avernging whenever incurrect responses wore made, and in some cascs none was nvnilablo so that the entrics were based on fewer than 600 run mcnw, ns indicntcd in pnrenthcaos. ltaliciserl figures aro either signal probability val~tcsor tnrgct distnncc vnlucs, as nppropriate. Starting positiion
A.
Correct reaction Lirucs Tnrgct pouit,ion
13. 3Iove1ncnt Limos Target positicrn 3 850
3 !)I8
I
2
0
I 707 1
I 700
"
I
1042 .3
")
HI!?
909
,
4
I074 3 975
!I25 0
883 I
3. Experimental Design We cwriecl out two experiments each occupying two weekends. Ihperimcnt I. used 1 2 subjects and lasted two days and one intervenit~gnight; Experiment 2 used eight other subjects and lasted three days and two intervening nights. I n both experitnents paid subjects ( 1 8-22 yr males) followed a Control Condition during which they slept 6:30 hr a t night, and a n IEsperimentd Condition in which they remained awake. They followed the two conditions on successive weekends, half in each order (thiit is, condition order was confounded \vit,h indivic1u;~ldifferences between subjects). Once every four hours each subject performed three trial runs on the stressalyser lasting 2-3 min per run, making, with rest pauses, about 12 min per session. Subjects were tested one a t a time ; ~ 1.5 t mi11 intervals, ~necliantimes of testing for the five daily sessions being 0880, 1230, 1630, 2030 and 0030 hr. Subjects pcrfornled twelve training runs with knowledge of rcsults (total time per run) some davs before the first weekend of the exlxximcnt. At the weekends th&c subjects following the IExperimentc~lConclition slcpt at thc 1,aboratory the previous (Thursday) night, while those following the Control
Downloaded by [NUS National University of Singapore] at 15:31 06 November 2015
41.8
Leslie Buck
Cotdition slept t ~ thomc, so tli;at for all subjects tcsts on :Day 1 represcntcd pcrfortniancc following n night. with slcep. Each subject followed tlie same testing scl~ctlr~lc on the two \vcekends. \IrIren tcstecl Ire sat alonc in a cubicle \\.Irere hc \VM \vi~tclrcdthrough closed-circuit television stid instructed tlirougll Ircradpliones. H e received no knomletlgc of results. Subjects following the t tluril& prescribed times which were staggered Control Condition slept t ~night so tlmt ci~clrslept 6:RO hr ancl was aroused 1 : 1 5 lrr before his first test of the tl;ay. :13ctween tcsts subjects diverted themselves with games, radio, television, tnusic, tnc;als, convcrs;ation imcl wi~lking,dl under close supervision. .In experiments of this design subjects become increiasingly deprived of sleep ~ t stlrc cxpcrimcnt procccds from the first test session. :However, during the cor~rscof iany one clay some viariiation of performance between t,ests may be cxpcctctl i ~ s;L consequence of tlrc coninronly observed circaclian rhythm of pcrform;ancc (Hoclrcy mrcl Colqnlroun 1072), :and i t is necessary to distinguish bctwccn this ;and tlrc varii~tionbctwccn di~ys. The effect of sleep loss may be cspcctcd to bc seen in differences in pcrfornrance between Day 1, Day 2, etc., for subjects following tlrc :ISxperirnentnl Condition, corresponding t o the effect of zcru, I , ctc., nights withont slcep, but a further effect might also be apparent in nn intcr;~ctionbetween diay and timc of clay. The design also contains a run within scssion ft~otur,hut prcliminnry i~nialysis(Back 1072) showed t h a t very little v;~ri;~ncc wi~s;attributable t o this, :and scores were iaccorclingly averaged cross runs within scssion. !l.'trr~sfour design factors were consiclerccl-Subjects, Conditions, Ilhys i ~ n d!Cinlcs of day-in addition t o t h e task factors of l'robnbility (2)) in tho case of rcact,ion timc i~ntlDistance (d) in the case of movement ti~nc. 4.
Results
'I'l~ceffect of onc night without slcep \v:as tlre same in Experiments 1 ancl 2: t l ~ c r e\ws no indici~tionthat the clri~ngein pcrformancc following sleep loss \v:as ;~ffectcdby tlrc number of cliays for \vtiich tlre experiment \\ws to run. I n considering tlie effect of one night without slccp (Day I versus Day 2) therefore the data for >all subjects from both experi~nents(a=20) were poolecl, while for two nights wjtliout slccp (Day I versrrs Dkay 3) the data of Experiment 2 (n= 8) wcrc t;alten alonc. 1ICigurc 2 slro\vs mcan correct reaction time scores, i~vcragedfor subjects, for for other 2) values arc the two extreme values of p = 0.26 and p = 1.00. (:l>ati~ given by :Buck and Leonardo 1072 :and 1073.) Tiable 2slro\vs differences bct\vccn days of t h e differences bct\vcen conditions for data. averegccl for subjects ;and t i n ~ c sof day, t h a t is: W,,c - i\'lcc)l,(?or :l) - (%C - ~~CC),), !l.'hcsc sllo~vtlmt the incrcese in correct reaction tinie follo\ving sleep loss v;rrictl inversely with .I, vi~lrlc,and that both thc increase and the interactive r t\vo nights \vitlrorrt sleep t,lran after one. effect of p \vias g ~ w t c after Il.'hcsc findings were tested for statisticd significance usingfivefactor CI.I~U~?/SCS c!f w r i t n m . :In tlrc first case (Ilhy I. versus Day 2) tlie Probability x Conclition x : l h ~ inte~.iwtion y \?iari;ancc was significant using a combined msidual and third ortlcr intert~ctionv;~riamceas the error term !P=7.21, clf = 3,753, P < 0.001.) but t h Condition x :lliay intcriaction vtariancc wns not using the former a s the crrvr term ( . F = 6.47, (If = J,3, 1' > 04.5). 1111 the second case (1Dey 1 versus
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Sleep Loss Bflects on Movmnent Time
n=20
Control Experimental p = 1.00 -
n:8
0
A
o
A
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p~0.25
Figure 2. Nenn correct rcact.ion tin~cs. Ench entry is tho mean of thrco trial means for 7r ~ubjcots. JJny 1 results nrc ahown for n = 2 0 a n d 11=8 so a s t o provide appropriate rlntn for nssessiug, respectively, tho c l h t r of ono night a n d two nights without sleep.
'J'nble 2. Jlcun rcnction tin10 scorcs (msec). Jlenns f w onch t&d run were computed by grouping dat,n for cuch target lnovelncnt according to the itnliciscd vnlucs of signul prohahility s h c w i i n Table IA. I n t,hc cnsc < ~d fa t a for T J = 1.00 ndditionnl r u n Incans wcrc computed by gmuping according t o t,he itnlicisetl vniuos of t w g o t dist,nnco shown i n T d h ID. Entries nrc menns f o 11~ s~thjoctsawl 15 clnily trinl runs. Alcans for I h y 1 a r e shc\vn for n = 2 0 a n d n = 8 in ordcr tu provide appropriate c o m p n r i s o ~ ~for - I h y 2 a n d Duy 3 rospcct,ivcly. T h c antrios in parentS~esoaa r e diffcrences bctmecn dnys of the differences betwecn Experimentnl (E) RIKI C o n t ~ o l(C) C:
