Neuropsychologia, 1976,Vol. 14, pp.211lo 216. Pergamon Press.Printed in England.
RECOGNITION OF VERBS, ABSTRACT NOUNS AND CONCRETE NOUNS FROM THE LEFT AND RIGHT VISUAL HALF-FIELDS DAVID
HINES
Department of Behavioral Science, The Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey, Pennsylvania 17033, U.S.A. (Received 6 May 1975) Abstract-Visual half-field recognition was evaluated for familiar and unfamiliar verbs, abstract nouns, and concrete nouns. The familiar abstract nouns showed a significantly greater right visual-half-field superiority than did the familiar concrete nouns; however, no difference in asymmetry was found for the unfamiliar abstract and concrete nouns. The greater right visual-half-field superiority for familiar abstract nouns was found under both unilateral and bilateral presentation, with fixation controlled using a center digit. It was suggested that the decreased asymmetry for familiar concrete nouns was due to recognition of these words by both the right and left hemispheres. INTRODUCTION OBSERVATIONS from
two split-brain patients suggest that the right hemisphere is capable of understanding visually presented nouns but not visually presented verbs [l]. When names of simple objects were presented to the left visual half-field (VHF), the patients were able to point to a picture of the object using their left hands. However, the patients were not able to point to some more difficult nouns (e.g. locker, teller) or to make appropriate responses to any verbs. Two experimenters have attempted to investigate this effect with normal subjects. CAPLAN, HOLMES, and MARSHALL [2] found no overall differences in VHF asymmetry between pure nouns, nouns derived from verbs (e.g. worker), and words which may be used as either nouns or verbs (e.g. master). While the noun-verb distinction was not supported, a difference in VHF asymmetry between concrete and abstract nouns has been reported. ELLIS and SHEPHERD [3] found that abstract nouns showed a larger left-right VHF asymmetry than did concrete nouns. The present experiment evaluates VHF asymmetry for both familiar and unfamiliar verbs, abstract nouns, and concrete nouns. Bilateral VHF presentation consistently produces a larger VHF asymmetry than unilateral presentation when fixation is controlled through a center digit, and may represent a more direct measure of the ability of the contralateral hemisphere [4]. The present experiment compares VHF asymmetry between word classes under both unilateral and bilateral conditions. Fixation was controlled for both the unilateral and bilateral conditions by presenting one or two single digits at fixation in addition to the VHF stimuli. METHOD Subjects Twenty employees and students of the Hershey Medical Center served as subjects. Each subject received $3 compensation for serving. 211
212
DAVID
HINES
Visual materials and equipmem
The stimuli were presented using a Gerbrands Four Channel (T4A) Tachistoscope. The words were constructed on white 4 x 6 in. cards using dry transfer lettering (Letraset 2218). The inner edge of each word was 1.7 degrees and the outer edge was 4.1 degrees from fixation. Each stimulus card contained a single digit from O-9 at fixation and one or two four-letter words. The fixation card consisted of six diagonal lines (30, 90, 150, 210, 270, and 330 degrees) radiating from a 1.4 cm open circle. The “open circle” design avoids masking effects on the center fixation digit and VHF words. All words used had four letters. The familiar verbs, abstract nouns, and concrete nouns all have an occurrence in general reading material of at least 100 per million [5]. The verbs were judged by the experimenter to have a high preferential use as verbs rather than nouns. The unfamiliar verbs averaged an occurrence of 9.5 per million, the unfamiliar abstract nouns an occurrence of 15.75 and the unfamiliar concrete nouns an occurrence of 14.75. The abstract and concrete nouns were taken from the 925 nouns scaled for concreteness, imagery, and meaningfulness by PAIVIO, YUILLE and MADIGAN [6]. The concrete nouns used in this study ranked high in concreteness (X = 6.83) and in imagery (X = 6.45). The abstract nouns ranked low in both concreteness (X = 2.77) and imagery (X = 2.58). The familiar verbs used were: does, have, give, and rverr. The unfamiliar verbs were: gape, omit, plod, and shun. The familiar abstract nouns were: soul,ficr, duty, and idea. The unfamiliar abstract nouns were: gist,pact. hint, and unit. The familiar concrete nouns were: gold, bird, ship and lake. The unfamiliar concrete nouns were: dove, lice, cane, and harp. Experimetlrtal condition Groups. Half of the subjects viewed the stimuli with one single digit at fixation;
the other half of the subjects viewed the stimuli with two successive single digits at fixation. All other conditions were given to all subjects. Subjects in the single digit conditions were alerted before each trial by the experimenter. The fixation “circle” then appeared for 2 set followed immediately by the stimulus card exposed for 20 msec, with a single digit appearing at fixation in addition to the VHF word(s). The subjects then reported the center digit and VHF word(s). While the center digit was always reported first, the two VHF words could be reported in any order. Subjects in the two digit condition were alerted and viewed the fixation card for 2 set and stimulus card for 20 msec as above. However, following the stimulus card a blank card appeared for 120 msec followed by a second digit appearing at the fixation point for 50 msec. The subjects then reported the two center digits (in any order) followed by the VHF word(s). All subjects were given 5 practice and 72 scored trials. Each of the 24 words appeared once in each field under both unilateral and bilateral conditions. The bilateral words were randomly paired without regard to type or frequency. The unilateral and bilateral trials were randomly alternated. The order in which each word appeared in each VHF and unilateral-bilateral condition was counter-balanced between subjects so that all individual words appeared first, second, third, or fourth in each condition for one fourth of the subjects. Thus any given word appeared first in the right VHF in unilateral presentation for five subjects, first in the right VHF under bilateral presentation for five subjects, first in the left VHF under unilateral presentation for five subjects and first in the left VHF under bilateral presentation for five subjects. The same counterbalancing was used for the second, third and fourth times a word appeared. Procedure
Each subject was given written instructions which explained the task and emphasized that he should always fixate the center circle, report the center digit(s) first, and then report the word(s) on each trial. Each was then administered the 5 practice and 72 scored trials. The subject’s responses were recorded by the experimenter after each trial. The entire session was completed within 45 min for each subject.
RESULTS The percent correct responses for each condition are shown in Table 1. A mixed analysis of variance was performed with the number of center digits as a between groups factor and the VHFs, unilateral-bilateral presentation, familiarity, and word class as within group factors. The analysis of main effects is shown in Table 2. All main effects except number of center digits were highly significant. Five interactions were also significant. All significant interactions were further examined using the Newman-Keuls procedure. The finding of most relevant to the purpose of this study was the significant VHF by word class by familiar-unfamiliar interaction (F = 7.90; crf-=2, 36, P -c 0*00.5). This
RECOGNITION
OF VERBS,
Table 1. Percent correct recognitions
ABSTRACT
NOUNS
AND
CONCRETE
from the left and right VHF’s for verbs, abstract nouns, and concrete nouns Bilateral
uni1atero1
center Verbs
Abstract NOUna
concrete Nouns
All words 1# + Z/j's
213
NOUNY
Unfamfliar
Familiar
Unfamiliar
Familiar LVHF 40.0 47.5
RVHF 62.5 62.5
LVHF 32.5 30.0
RVHF 45.0 40.0
LVHF 35.0 20.0
RVHE 72.5 55.0
LVHF 17.5 5.0
RVHF 45.0 35.0
mean
43.75
62.5
31.25
42.5
27.5
63.75
11.25
40.0
10 2P'a
57.5 55.0
90.0 90.0
45.0 40.0
60.0 47.5
45.0 30.0
95.0 82.5
35.0 20.0
62.5 35.0
mean
56.25
90.0
42.5
53.75
37.5
88.75
27.5
48.75
1# 2#'s
65.0 77.5
82.5 85.0
40.0 27.5
60.0 45.0
45.0 40.0
72.5 67.5
37.5 15.0
70.0 52.5
me*n
71.25
83.75
33.75
52.5
42.5
70.0
26.i5
61.25
57.08
78.75
35.83
49.58
35.83
74.16
21.66
50.00
Digtt l# 28'S
Table 2. Analysis of main effects
Left VHF Right VHF
48.4 54.7
1, 1Y
125.05
48.4
.OOl
Unilateral Bilateral
58.3 45.4
1, 18
18.81
31.8
.OOl
Familiar Unfamiliar
61.4 32.5
1, 18
94.52
70.4
.OOl
55.6 55.2 40.3
2, 36
19.41
38.1
.OOl
54.7 46.0
1, 18
14.35
1.18
N.S.
18 at fixation 2t at fixation
interaction apparently reflects a much larger right VHF superiority for familiar abstract nouns than for familiar concrete nouns. Subjects recognized significantly more familiar abstract than familiar concrete nouns from the right VHF (P .c 0.01); but tended to recognize more familiar concrete than familiar abstract nouns from the left VHF. This interaction is illustrated in the left half of Fig. 1. As can also be observed in Fig. , the larger right VHF superiority was found only for the familiar abstract nouns. For the unfamiliar nouns the opposite tendency was observed. However, neither the relative right VHF superiority for unfamiliar concrete nouns over unfamiliar abstract nouns nor the left VHF asymmetry for unfamiliar abstract over unfamiliar concrete nouns proved significant. The verbs were recognized less accurately under all conditions. Four other interactions were statistically significant. The VHF by unilateral-bilateral presentation interaction (F = 22.2; df = 1, 18; P < 0401) indicates that subjects demonstrated greater VHF asymmetry under the bilateral than unilateral presentation. Subjects showed no significant differences between the unilateral-bilateral conditions from the right VHF but recognized significantly fewer words from the left VHF in the bilateral conditions (P < 0.01). The interaction between the unilateral-bilateral presentation conditions and the
214
DAVID
HINES
RIGHT VHF--LEFT VHF-
80
Abstract
Concrete
Abstract
Concrete
FIG.1.Visual half-field (VHF) asymmetry for familiar and unfamiliar abstract and concrete nouns. The familiar abstract nouns shown significantly larger right VHF superiority than the familiar concrete nouns.
number of center digits (F = 11.4; df = 1, 18; P < 0*005) reflects the decreased recognition when two center digits are presented from the bilateral but not the unilateral conditions. Subsequent tests indicate no differences in recall between the unilateral and bilateral conditions when one center digit is presented, but significantly greater recall from the unilateral condition when two center digits are presented. The significant familiar-unfamiliar by VHF interaction (F = 4.56, df = 1, 18 ; P < 0.05) reflects the increased VHF asymmetry for the familiar words. The familiar-unfamiliar by word class by unilateral-bilateral interaction (F = 5.74; df = 2, 36; P < 0.01) reflects the larger asymmetry between the unilateral and bilateral conditions for familiar concrete nouns. Subjects showed a large difference favoring the unilateral condition for familiar concrete words (P < 0.01) but the slight advantage for the bilateral condition for unfamiliar nouns was not significant. DISCUSSION The right VHF superiority for words and the superior recognition for familiar words both reflect well established effects. The significantly larger right VHF superiority under the bilateral viewing condition has also been reported in several previous experiments. The larger VHF asymmetry for familiar abstract over concrete nouns is a partial replication of ELLIS and SHEPHERD [3]. Ellis and Shepherd utilized 20 abstract and 20 concrete nouns which were equated for THORNDIKE-LORGE [5] frequency. However, they did not differentiate between familiar and unfamiliar nouns. The present findings strongly indicate that this effect is limited to familiar nouns. The familiar abstract and concrete nouns in the present study displayed almost identical overall recognition (Abstract = 55.6 %; Concrete = 55.2 %). Thus the large asymmetry sometimes associated with more difficult stimulus conditions in binocular recognition experiments [8] cannot explain the present results. HINES [4] has hypothesized that the right VHF superiority for verbal stimuli may be influenced by two distinct CNS mechanisms. First, words presented initially to the right hemisphere (via the left VHF) may cross the callosum and be recognized by the left hemisphere. Asymmetry produced by crossing the callosum should be constant for any class of
RECOGNITIONOF VERBS, ABSTRACTNOUNSAND CONCRETENOUNS
215
verbal stimuli since there is no reason for different classes to be differently degraded in transmission across the callosum. Second, stimuli presented to the left VHF may be recognized directly by the right hemisphere without crossing the callosum. The hypothesis that the two hemispheres may work as “independent channels” for processing of VHF stimuli has been discussed extensively by DIMOND [7]. The difference in VHF asymmetry between familiar abstract and concrete nouns suggests that some familiar concrete nouns are recognized independently by the right hemisphere (thereby increasing recognition from the left VHF) since there is no reason to postulate dilrerences between abstract and concrete nouns in transmission loss. A similar interpretation was given by ELLIS and SHEPHERD [3]. However, the right VHF superiority for unfamiliar wqrds was probably due to transmission loss in crossing the callosum, since it did not differ across word classes. It seems most reasonable to assume that few, if any, of the unfamiliar words were independently recognized by the right hemisphere. HINES [4] has suggested the term “selective channelling” to indicate that the two hemispheres may sometimes, but not always, operate as independent processing channels for recognizing new stimuli. The results of this experiment suggest that the right hemisphere may be limited in capacity for independently recognizing left VHF words by its inferior visual language skills; although it is still possible that the two hemispheres operate as separate channels for processing less linguistically complex aspects of VHF stimuli, such as recognition of individual letters [7, 91. The results of the present experiment seem most readily explainable by a two mechanism hypothesis, such as the selective channel theory. The differences between familiar abstract and concrete nouns indicate right hemisphere recognition of familiar concrete nouns from the left VHF. The consistent right VHF superiority for unfamiliar words indicates that when left VHF words cannot be recognized independently by the right hemisphere, there is a loss of recognition associated with transmission to the left hemisphere. Hines also has suggested that the two hemispheres are most likely to operate as independent channels under bilateral presentation conditions. However, this hypothesis was not supported by the present experiment. REFERENCES 1. GAZZANIGA, M. The Bisected Bruin. Appleton-Century-Crofts, New York, 1970. 2. CAPLAN, D., HOLMES, J. M. and MARSHALL, J. C. Word class and hemispheric specialization.
Neuropsychologia 12,331-337, 1974. 3. ELLIS, H. D. and SHEPHERD, J. W. Recognition of abstract and concrete words presented in left and right visual fields. J. exp. Psycho!. 103,1035-1036, 1974. 4. HINES, D. Independent functioning of the two cerebral hemispheres for recognizing bilaterally presented tachistoscopic visual-half field stimuli. Cortex l&132-143,197s. 5. THORNDIKE, E. L. and LORGE, I. The Teachers Workbook of 30,000 words. Teachers College Bureau of Publication, New York, 1944. 6. PAIVIO, A., YUILLE, J. C. and MADIGAN, S. A. Concreteness, imagery - _ and meaningfulness values of 925 nouns. J. exp. Psychol. Mono. Supp. 76, (1, Pr. 2), 1968. 7. DIMOND, S. J. The Double Brain. Williams & Williams. Baltimore. 1972. 8. MACKA~EY, W., CURCIO, F. and ROSEN, J. Tachistoscbpic word recognition performance under conditions of simultaneous bilateral presentation. Neuropsychologiu 13, 27-33, 1975. 9. MOSCO~ITCH, M. Choice reaction-time assessing the verbal behavior of the minor hemisphere in normal adult humans. J. Comp. physiol. Psychol. 80, 66-74, 1972.
DAVID HINES
216
On a Walu6
verbes,familfers
ia
reconnaissance
des h&nlchamps visuels pour lee
et non fsmiliers,
les noms abstraits et les noms concrets. 11 existait une supSriorit6 de l'h&nichamp droft significative-
ment plus grande pour les noms abstraits familiers que pour les noms concrets famfliers; mats aucune difference dans l'asym6trien'etait constat&e pour les noms abstraits non familiers et pour les noms concrets. La plus grande superiorit
de l'h&nfchamp droit pour les noms abstraits
familiers Btait trouve avec des pr&entations bilatkales,
soit unilaterales
soit
la fixation etant contr616e en titilisant un chiffre au
centre. 11 est propose que la diminution de l'asym6trie pour les noms concrets familiers est dGe a ce que la reconnaissance
de ces mots est
r@alisee par les deux h&nisphkes.
Deutschsprachige Zusammenfassung: In den GesichtsfeldhCilftenwurde das Erkennen von gebrluchlichen und ungebrguchlichen Verben und von abstrakten und konkreten Substantiven'bestimmt. Es zeigte sich, daB eine signifikante ttberlegenheitder rechten GesichtsfeldhUfte flirgebrauchliche abstrakte Substantive im Vergleich au gebrguchlichen konkreten Substantiven bestand. Dagegen lag kein Asymmetrieverhiiltnisvor in Bezug auf ungebrluchliche abstrakte und konkrete Substantive. Die gr6Bere RechtsHalbfeld-Uberlegenheit fur gebrtiuchlicheabstrakte Substantive wurde wowohl unter unilateraler wie bilateraler Prgsentation gefunden, wobei die Fixation durch Verwendung einer zentral angebrachten Ziffer kontrolliert wurde. Es wurde zu bedenken gegeben, daI3die verminderte Asymmetric fiirgebrPuchliche konkrete Substantive auf das Erkennen dieser WBrter durch beide, die rechte und die linke Hecisphlre zurllckzufiihren sei.
RECOGNITION OF VERBS, ABSTRACT NOUNS AND CONCRETE NOUNS FROM THE LEFT AND RIGHT VISUAL HALF-FIELDS DAVID
HINES
Department of Behavioral Science, The Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey, Pennsylvania 17033, U.S.A. (Received 6 May 1975) Abstract-Visual half-field recognition was evaluated for familiar and unfamiliar verbs, abstract nouns, and concrete nouns. The familiar abstract nouns showed a significantly greater right visual-half-field superiority than did the familiar concrete nouns; however, no difference in asymmetry was found for the unfamiliar abstract and concrete nouns. The greater right visual-half-field superiority for familiar abstract nouns was found under both unilateral and bilateral presentation, with fixation controlled using a center digit. It was suggested that the decreased asymmetry for familiar concrete nouns was due to recognition of these words by both the right and left hemispheres. INTRODUCTION OBSERVATIONS from
two split-brain patients suggest that the right hemisphere is capable of understanding visually presented nouns but not visually presented verbs [l]. When names of simple objects were presented to the left visual half-field (VHF), the patients were able to point to a picture of the object using their left hands. However, the patients were not able to point to some more difficult nouns (e.g. locker, teller) or to make appropriate responses to any verbs. Two experimenters have attempted to investigate this effect with normal subjects. CAPLAN, HOLMES, and MARSHALL [2] found no overall differences in VHF asymmetry between pure nouns, nouns derived from verbs (e.g. worker), and words which may be used as either nouns or verbs (e.g. master). While the noun-verb distinction was not supported, a difference in VHF asymmetry between concrete and abstract nouns has been reported. ELLIS and SHEPHERD [3] found that abstract nouns showed a larger left-right VHF asymmetry than did concrete nouns. The present experiment evaluates VHF asymmetry for both familiar and unfamiliar verbs, abstract nouns, and concrete nouns. Bilateral VHF presentation consistently produces a larger VHF asymmetry than unilateral presentation when fixation is controlled through a center digit, and may represent a more direct measure of the ability of the contralateral hemisphere [4]. The present experiment compares VHF asymmetry between word classes under both unilateral and bilateral conditions. Fixation was controlled for both the unilateral and bilateral conditions by presenting one or two single digits at fixation in addition to the VHF stimuli. METHOD Subjects Twenty employees and students of the Hershey Medical Center served as subjects. Each subject received $3 compensation for serving. 211
212
DAVID
HINES
Visual materials and equipmem
The stimuli were presented using a Gerbrands Four Channel (T4A) Tachistoscope. The words were constructed on white 4 x 6 in. cards using dry transfer lettering (Letraset 2218). The inner edge of each word was 1.7 degrees and the outer edge was 4.1 degrees from fixation. Each stimulus card contained a single digit from O-9 at fixation and one or two four-letter words. The fixation card consisted of six diagonal lines (30, 90, 150, 210, 270, and 330 degrees) radiating from a 1.4 cm open circle. The “open circle” design avoids masking effects on the center fixation digit and VHF words. All words used had four letters. The familiar verbs, abstract nouns, and concrete nouns all have an occurrence in general reading material of at least 100 per million [5]. The verbs were judged by the experimenter to have a high preferential use as verbs rather than nouns. The unfamiliar verbs averaged an occurrence of 9.5 per million, the unfamiliar abstract nouns an occurrence of 15.75 and the unfamiliar concrete nouns an occurrence of 14.75. The abstract and concrete nouns were taken from the 925 nouns scaled for concreteness, imagery, and meaningfulness by PAIVIO, YUILLE and MADIGAN [6]. The concrete nouns used in this study ranked high in concreteness (X = 6.83) and in imagery (X = 6.45). The abstract nouns ranked low in both concreteness (X = 2.77) and imagery (X = 2.58). The familiar verbs used were: does, have, give, and rverr. The unfamiliar verbs were: gape, omit, plod, and shun. The familiar abstract nouns were: soul,ficr, duty, and idea. The unfamiliar abstract nouns were: gist,pact. hint, and unit. The familiar concrete nouns were: gold, bird, ship and lake. The unfamiliar concrete nouns were: dove, lice, cane, and harp. Experimetlrtal condition Groups. Half of the subjects viewed the stimuli with one single digit at fixation;
the other half of the subjects viewed the stimuli with two successive single digits at fixation. All other conditions were given to all subjects. Subjects in the single digit conditions were alerted before each trial by the experimenter. The fixation “circle” then appeared for 2 set followed immediately by the stimulus card exposed for 20 msec, with a single digit appearing at fixation in addition to the VHF word(s). The subjects then reported the center digit and VHF word(s). While the center digit was always reported first, the two VHF words could be reported in any order. Subjects in the two digit condition were alerted and viewed the fixation card for 2 set and stimulus card for 20 msec as above. However, following the stimulus card a blank card appeared for 120 msec followed by a second digit appearing at the fixation point for 50 msec. The subjects then reported the two center digits (in any order) followed by the VHF word(s). All subjects were given 5 practice and 72 scored trials. Each of the 24 words appeared once in each field under both unilateral and bilateral conditions. The bilateral words were randomly paired without regard to type or frequency. The unilateral and bilateral trials were randomly alternated. The order in which each word appeared in each VHF and unilateral-bilateral condition was counter-balanced between subjects so that all individual words appeared first, second, third, or fourth in each condition for one fourth of the subjects. Thus any given word appeared first in the right VHF in unilateral presentation for five subjects, first in the right VHF under bilateral presentation for five subjects, first in the left VHF under unilateral presentation for five subjects and first in the left VHF under bilateral presentation for five subjects. The same counterbalancing was used for the second, third and fourth times a word appeared. Procedure
Each subject was given written instructions which explained the task and emphasized that he should always fixate the center circle, report the center digit(s) first, and then report the word(s) on each trial. Each was then administered the 5 practice and 72 scored trials. The subject’s responses were recorded by the experimenter after each trial. The entire session was completed within 45 min for each subject.
RESULTS The percent correct responses for each condition are shown in Table 1. A mixed analysis of variance was performed with the number of center digits as a between groups factor and the VHFs, unilateral-bilateral presentation, familiarity, and word class as within group factors. The analysis of main effects is shown in Table 2. All main effects except number of center digits were highly significant. Five interactions were also significant. All significant interactions were further examined using the Newman-Keuls procedure. The finding of most relevant to the purpose of this study was the significant VHF by word class by familiar-unfamiliar interaction (F = 7.90; crf-=2, 36, P -c 0*00.5). This
RECOGNITION
OF VERBS,
Table 1. Percent correct recognitions
ABSTRACT
NOUNS
AND
CONCRETE
from the left and right VHF’s for verbs, abstract nouns, and concrete nouns Bilateral
uni1atero1
center Verbs
Abstract NOUna
concrete Nouns
All words 1# + Z/j's
213
NOUNY
Unfamfliar
Familiar
Unfamiliar
Familiar LVHF 40.0 47.5
RVHF 62.5 62.5
LVHF 32.5 30.0
RVHF 45.0 40.0
LVHF 35.0 20.0
RVHE 72.5 55.0
LVHF 17.5 5.0
RVHF 45.0 35.0
mean
43.75
62.5
31.25
42.5
27.5
63.75
11.25
40.0
10 2P'a
57.5 55.0
90.0 90.0
45.0 40.0
60.0 47.5
45.0 30.0
95.0 82.5
35.0 20.0
62.5 35.0
mean
56.25
90.0
42.5
53.75
37.5
88.75
27.5
48.75
1# 2#'s
65.0 77.5
82.5 85.0
40.0 27.5
60.0 45.0
45.0 40.0
72.5 67.5
37.5 15.0
70.0 52.5
me*n
71.25
83.75
33.75
52.5
42.5
70.0
26.i5
61.25
57.08
78.75
35.83
49.58
35.83
74.16
21.66
50.00
Digtt l# 28'S
Table 2. Analysis of main effects
Left VHF Right VHF
48.4 54.7
1, 1Y
125.05
48.4
.OOl
Unilateral Bilateral
58.3 45.4
1, 18
18.81
31.8
.OOl
Familiar Unfamiliar
61.4 32.5
1, 18
94.52
70.4
.OOl
55.6 55.2 40.3
2, 36
19.41
38.1
.OOl
54.7 46.0
1, 18
14.35
1.18
N.S.
18 at fixation 2t at fixation
interaction apparently reflects a much larger right VHF superiority for familiar abstract nouns than for familiar concrete nouns. Subjects recognized significantly more familiar abstract than familiar concrete nouns from the right VHF (P .c 0.01); but tended to recognize more familiar concrete than familiar abstract nouns from the left VHF. This interaction is illustrated in the left half of Fig. 1. As can also be observed in Fig. , the larger right VHF superiority was found only for the familiar abstract nouns. For the unfamiliar nouns the opposite tendency was observed. However, neither the relative right VHF superiority for unfamiliar concrete nouns over unfamiliar abstract nouns nor the left VHF asymmetry for unfamiliar abstract over unfamiliar concrete nouns proved significant. The verbs were recognized less accurately under all conditions. Four other interactions were statistically significant. The VHF by unilateral-bilateral presentation interaction (F = 22.2; df = 1, 18; P < 0401) indicates that subjects demonstrated greater VHF asymmetry under the bilateral than unilateral presentation. Subjects showed no significant differences between the unilateral-bilateral conditions from the right VHF but recognized significantly fewer words from the left VHF in the bilateral conditions (P < 0.01). The interaction between the unilateral-bilateral presentation conditions and the
214
DAVID
HINES
RIGHT VHF--LEFT VHF-
80
Abstract
Concrete
Abstract
Concrete
FIG.1.Visual half-field (VHF) asymmetry for familiar and unfamiliar abstract and concrete nouns. The familiar abstract nouns shown significantly larger right VHF superiority than the familiar concrete nouns.
number of center digits (F = 11.4; df = 1, 18; P < 0*005) reflects the decreased recognition when two center digits are presented from the bilateral but not the unilateral conditions. Subsequent tests indicate no differences in recall between the unilateral and bilateral conditions when one center digit is presented, but significantly greater recall from the unilateral condition when two center digits are presented. The significant familiar-unfamiliar by VHF interaction (F = 4.56, df = 1, 18 ; P < 0.05) reflects the increased VHF asymmetry for the familiar words. The familiar-unfamiliar by word class by unilateral-bilateral interaction (F = 5.74; df = 2, 36; P < 0.01) reflects the larger asymmetry between the unilateral and bilateral conditions for familiar concrete nouns. Subjects showed a large difference favoring the unilateral condition for familiar concrete words (P < 0.01) but the slight advantage for the bilateral condition for unfamiliar nouns was not significant. DISCUSSION The right VHF superiority for words and the superior recognition for familiar words both reflect well established effects. The significantly larger right VHF superiority under the bilateral viewing condition has also been reported in several previous experiments. The larger VHF asymmetry for familiar abstract over concrete nouns is a partial replication of ELLIS and SHEPHERD [3]. Ellis and Shepherd utilized 20 abstract and 20 concrete nouns which were equated for THORNDIKE-LORGE [5] frequency. However, they did not differentiate between familiar and unfamiliar nouns. The present findings strongly indicate that this effect is limited to familiar nouns. The familiar abstract and concrete nouns in the present study displayed almost identical overall recognition (Abstract = 55.6 %; Concrete = 55.2 %). Thus the large asymmetry sometimes associated with more difficult stimulus conditions in binocular recognition experiments [8] cannot explain the present results. HINES [4] has hypothesized that the right VHF superiority for verbal stimuli may be influenced by two distinct CNS mechanisms. First, words presented initially to the right hemisphere (via the left VHF) may cross the callosum and be recognized by the left hemisphere. Asymmetry produced by crossing the callosum should be constant for any class of
RECOGNITIONOF VERBS, ABSTRACTNOUNSAND CONCRETENOUNS
215
verbal stimuli since there is no reason for different classes to be differently degraded in transmission across the callosum. Second, stimuli presented to the left VHF may be recognized directly by the right hemisphere without crossing the callosum. The hypothesis that the two hemispheres may work as “independent channels” for processing of VHF stimuli has been discussed extensively by DIMOND [7]. The difference in VHF asymmetry between familiar abstract and concrete nouns suggests that some familiar concrete nouns are recognized independently by the right hemisphere (thereby increasing recognition from the left VHF) since there is no reason to postulate dilrerences between abstract and concrete nouns in transmission loss. A similar interpretation was given by ELLIS and SHEPHERD [3]. However, the right VHF superiority for unfamiliar wqrds was probably due to transmission loss in crossing the callosum, since it did not differ across word classes. It seems most reasonable to assume that few, if any, of the unfamiliar words were independently recognized by the right hemisphere. HINES [4] has suggested the term “selective channelling” to indicate that the two hemispheres may sometimes, but not always, operate as independent processing channels for recognizing new stimuli. The results of this experiment suggest that the right hemisphere may be limited in capacity for independently recognizing left VHF words by its inferior visual language skills; although it is still possible that the two hemispheres operate as separate channels for processing less linguistically complex aspects of VHF stimuli, such as recognition of individual letters [7, 91. The results of the present experiment seem most readily explainable by a two mechanism hypothesis, such as the selective channel theory. The differences between familiar abstract and concrete nouns indicate right hemisphere recognition of familiar concrete nouns from the left VHF. The consistent right VHF superiority for unfamiliar words indicates that when left VHF words cannot be recognized independently by the right hemisphere, there is a loss of recognition associated with transmission to the left hemisphere. Hines also has suggested that the two hemispheres are most likely to operate as independent channels under bilateral presentation conditions. However, this hypothesis was not supported by the present experiment. REFERENCES 1. GAZZANIGA, M. The Bisected Bruin. Appleton-Century-Crofts, New York, 1970. 2. CAPLAN, D., HOLMES, J. M. and MARSHALL, J. C. Word class and hemispheric specialization.
Neuropsychologia 12,331-337, 1974. 3. ELLIS, H. D. and SHEPHERD, J. W. Recognition of abstract and concrete words presented in left and right visual fields. J. exp. Psycho!. 103,1035-1036, 1974. 4. HINES, D. Independent functioning of the two cerebral hemispheres for recognizing bilaterally presented tachistoscopic visual-half field stimuli. Cortex l&132-143,197s. 5. THORNDIKE, E. L. and LORGE, I. The Teachers Workbook of 30,000 words. Teachers College Bureau of Publication, New York, 1944. 6. PAIVIO, A., YUILLE, J. C. and MADIGAN, S. A. Concreteness, imagery - _ and meaningfulness values of 925 nouns. J. exp. Psychol. Mono. Supp. 76, (1, Pr. 2), 1968. 7. DIMOND, S. J. The Double Brain. Williams & Williams. Baltimore. 1972. 8. MACKA~EY, W., CURCIO, F. and ROSEN, J. Tachistoscbpic word recognition performance under conditions of simultaneous bilateral presentation. Neuropsychologiu 13, 27-33, 1975. 9. MOSCO~ITCH, M. Choice reaction-time assessing the verbal behavior of the minor hemisphere in normal adult humans. J. Comp. physiol. Psychol. 80, 66-74, 1972.
DAVID HINES
216
On a Walu6
verbes,familfers
ia
reconnaissance
des h&nlchamps visuels pour lee
et non fsmiliers,
les noms abstraits et les noms concrets. 11 existait une supSriorit6 de l'h&nichamp droft significative-
ment plus grande pour les noms abstraits familiers que pour les noms concrets famfliers; mats aucune difference dans l'asym6trien'etait constat&e pour les noms abstraits non familiers et pour les noms concrets. La plus grande superiorit
de l'h&nfchamp droit pour les noms abstraits
familiers Btait trouve avec des pr&entations bilatkales,
soit unilaterales
soit
la fixation etant contr616e en titilisant un chiffre au
centre. 11 est propose que la diminution de l'asym6trie pour les noms concrets familiers est dGe a ce que la reconnaissance
de ces mots est
r@alisee par les deux h&nisphkes.
Deutschsprachige Zusammenfassung: In den GesichtsfeldhCilftenwurde das Erkennen von gebrluchlichen und ungebrguchlichen Verben und von abstrakten und konkreten Substantiven'bestimmt. Es zeigte sich, daB eine signifikante ttberlegenheitder rechten GesichtsfeldhUfte flirgebrauchliche abstrakte Substantive im Vergleich au gebrguchlichen konkreten Substantiven bestand. Dagegen lag kein Asymmetrieverhiiltnisvor in Bezug auf ungebrluchliche abstrakte und konkrete Substantive. Die gr6Bere RechtsHalbfeld-Uberlegenheit fur gebrtiuchlicheabstrakte Substantive wurde wowohl unter unilateraler wie bilateraler Prgsentation gefunden, wobei die Fixation durch Verwendung einer zentral angebrachten Ziffer kontrolliert wurde. Es wurde zu bedenken gegeben, daI3die verminderte Asymmetric fiirgebrPuchliche konkrete Substantive auf das Erkennen dieser WBrter durch beide, die rechte und die linke Hecisphlre zurllckzufiihren sei.
