VISUAL INFORMATION PROCESSING IN THE LEFT AND RIGHT HEMISPHERES*

DAVID HINES

Department of Behavioral Science, The Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey, Pennsylvania 17033, U.S.A.

(Received 28 March 1978)

Abstract--The effect of verbal vs nonverbal center fixation stimuli on visual half-field (VHF) asymmetry was investigated using both verbal and nonverbal VHF stimuli. Twenty adult subiects were administered word. face. and random shape VHF stimuli under both unilateral-and bilateral viewing conditions.

The results showed that VHF asymmetry was determined primarily by type of VHF stimuli under all viewina conditions, Words were recoanized more often from the right VHF, faces were recognized more often from the left VHF, r&d random shapes showed no &ni6cant VHF difference. The results indicate that VHF asymmetry reflects ditTerences in information processing capacity between the left and right hemispheres.

KERSHNER, TOMAE and CALLAWAY [l] have found that the fixation control methods used in studies of bilateral tachistoscopic presentation may exert a “powerful effect” on visual half-field (VHF) differences. Using young children as subjects, they found a right VHF superiority for digits, when digits were also used as the center control stimuli. However, they found a left VHF superiority for digits when a nonverbal fixation control (simple forms) was employed. They interpreted their results in terms of the attentional-set mechan- isms suggested by KINSBOURNE [2]; that is, they suggested that “when the children were required to attend a verbal fixation target, greater activation of the left hemisphere produced an attentional set to the opposite VHF. Similarly, when the children were required to identify manually a nonverbal fixation target, greater activation of the right hemisphere triggered a left VHF perceptual bias” [l, p. 5731. Kershner et al. pointed out that this interpretation invalidates studies which attempt to use VHF asymmetry to investigate “fixed or developmentally graded hemispheric differences” [ 1, p. 5743.

The Kershner et al. findings present difficulties for hypothesis which attribute VHF asymmetry to differences in hemispheric information processing capacity [3, 41. However, Kershner et al. also pointed out some differences between their experimental conditions and these typically employed in studies of VHF asymmetry. In particular they noted that the young children used as subjects in their experiments may be less lateralized for language than adults and that their digit recognition might be less “linguistic” than word recognition. In addition, KERSHNER et al. presented their stimulus at a relatively long presentation interval (10&140 msec) in comparison to most other studies (usually 20 msec). GILL and MCKEEVER [5] have shown that right VHF superiority for bilaterally presented words is

*This study is based on a paper presented at the International Neuropsychological Society on 3 February, 1978.

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594 DA~IIJ HINES

severely attenuated at longer presentation intervals, and eliminated for two letter words presented for 100 msec.

The experiment to be reported tested whether type of fixation stimulus (verbal or non- verbal) alters VHF asymmetry under any of the common adult experimental paradigms. Thus the effect of verbal vs nonverbal fixation control was tested under unilateral presentation of verbal (word) stimuli, bilateral presentation of verbal stimuli, unilateral presentation of nonverbal (face and random shape) stimuli and bilateral presentation of nonverbal stimuli. The verbal center control stimulus were single digits and the nonverbal center control stimuli were 8 slanted lines. The line stimuli and answer card were adapted from FONTENOT and BENTON [6], with the deletion of horizontal and vertical lines which do not reliably produce a left VHF recognition superiority in other studies [7]. The slanted lines were arranged in random order on the answer sheet to minimize any verbal coding.

In addition, the order of presentation was arranged so that any verbal or nonverbal “attentional set” would be consistent with the type of center fixation stimulus, rather than the type of VHF stimulus. Thus the block of 60 trials which presented verbal center control stimulus with nonverbal VHF stimuli was immediately preceded by a block of 60 trials in which both the center control stimuli and the VHF stimuli were verbal. Similarly, the non- verbal fixation-verbal VHF block of trials was immediately preceded by a block of 60 trials in which both the center and VHF stimuli were nonverbal.

If the Kershner et al. findings generalize to these experimental conditions, then one would predict a general right VHF superiority when a verbal center fixation stimulus was presented, regardless of VHF stimuli, and a left VHF superiority when a nonverbal fixation stimulus is used, regardless of the VHF stimuli. However, if VHF asymmetries depend on hemispheric differences, then one would expect a right VHF superiority for verbal VHF stimuli and a left VHF superiority for the nonverbal VHF stimuli, regardless of which type of central fixation stimulus is employed.

METHOD Subjects

Twenty right-handed subjects were recruited through notices displayed on bulletin boards at the Hershey Medical Center. Most were either students or employees at the Medical Center. All subjects were at least high school graduates. Each subject received $6 compensation for serving.

Visual materials and equipment The stimuli were presented using a Gerbrands Harvard T4A Tachistoscope. The illumination for all four

fields was set at 100%. Field 4 of the tachistoscope was used to present the stimulus card, Field 3 the fixation card and Field 2 a blank white card. The viewing distance for the T4A is 21 in. (53.34 cm).

Twenty words from the SPREEN and SCHULTZ 181 list of 329 nouns ranked for abstractness, meaningfulness, and pronounceability were used in the experiment. Only 5 letter words with no double letters were used. Within these constraints, the ten words ranked highest in abstractness and the ten words ranked lowest in abstractness were selected. All words on the Spreen and Schultz list have a THORNDIKE--LORGE [9] frequency of 50-100 per million words (“A” frequency).

The words were typed in all capitals on 4 x 6 file cards using IBM Orator electric typeface. Each letter was 4 mm high and about 2 mm in width. The words were typed with a space between e&h letter and six spaces between the VHF word and the center digit on the verbal fixation cards. The inner edae of each word was about 1.4 cm from the center of fixation and the outer edge about 3.8 cm from the center of fixation. Each word was presented once in each VHF for all of the experimental conditions of a total of eight times.

The experiment used 240 random shapes from the series described by BROWN and OWEN [lo]. Test stimuli on the scored trials were 24 8-point random shapes, 24 16-point shapes, and 32 20-point shapes. In each of the eight experimental conditions, 3 8-point, 3 16-point, and 4 20-point shapes were used. Each shape stimulus, consisting of a filled-in, black, random polygon against a white background, was contained within a 5 cm square. The stimuli were mounted on 4 x 6 file cards with the inner edge of the shape about 1.4 cm from the center of fixation.

Duplicates of the presentation stimuli plus the remaining unpresented shape stimuli were used to construct the answer sheets. Each answer sheet consisted of a presentation random shape plus two unfamiliar shapes at the same level of complexity.

The face stimuli were obtained from class pictures of previously graduated medical students. Each 2.5 x 3.5 cm picture contained a single full face. The pictures were relatively homogeneous with respect to face size, picture background and contrast. Eighty of the pictures were mounted 1.4 cm from the center of fixation on 4 x 6 file cards to be used as test stimuli. Duplicates of these pictures plus an additional 160 unfamiliar pictures were used in constructing the answer sheets. Each answer sheet contained a duplicate of the stimulus face plus two unfamiliar foils. As far as possible, the incorrect choices were matched to the correct choice for orientation, hair length, sex, facial expression and presence of glasses or facial hair.

The nonverbal center fixation stimuli were duplicates of eight black slanted lines 8 cm in length. The lines were constructed with 18” between adjacent lines and the horizontal and vertical lines were deleted. Each stimuli line was presented at the center of fixation on a 4 x 6 file card. An answer card was also constructed for use on the nonverbal center fixation trials. The answer card contained all 8 slanted lines in a random order. This task was adapted from FONTENOT and BENTON [6].

Procedure There were four blocks of trials presented to all subjects: verbal center stimuli - verbal VHF stimuli

(K-V), verbal center stimuli - nonverbal VHF stimuli (VC-N), nonverbal center stimuli - verbal VHF stimuli (NC-V), and nonverbal center stimuli - nonverbal VHF stimuli (NC-N). Each block consisted of six practice trials and 60 scored trials. Within each block 40 unilateral VHF trials were randomly alternated with 20 bilateral VHF trials. On the unilateral trials the VHF in which the stimulus was presented was randomly alternated. The six practice trials consisted of four unilateral trials and two bilateral trials.

Half of the subjects viewed the trials in order VC-V, VGN, NC-N and NGV. The remaining 10 subjects viewed them in the order of NGN, NC-V, VGV and VC-N. All subjects viewed the practice trials in their first verbal VHF condition (VC-V or NGV) at the rate of 30 msec solidus stimulus. Subjects who recognized two or less of the eight words presented on the practice trials viewed the remaining trials in which words were presented in the VHF’s at 40 msec each. Subjects who recognixed 3-5 of the 8 practice words viewed all remaining verbal VHF trials at 30 msec, while subjects who recognized 6-8 of the practice words viewed the remaining verbal VHF trials at 20 msec.

Similarly all subjects viewed the practice trials in their first block of trials in which shapes and faces were presented in the VHF’s (VGN or NGN) at 80 msec. The remaining trials in which shapes and faces appeared in the VHF were presented at 90 msec if a subject recognized four or less of the eight practice VHF stimuli, at 80 msec if a subject recognized 5-6 of the eight stimuli and at 70 msec if subjects recognized 7-8 of the practice VHF faces and shapes. The average presentation time for the word stimuli was 38 msec and for the face and shape stimuli 80 msec.

In the VGV block of trials, a center cross was presented for 400 msec at the beginning of each trial, followed immediately by the stimulus card. Each stimulus card contained a single digit at the center of fixation plus a word in one VHF on the unilateral trials, or a word in both VHF’s on the bilateral trials. Subjects were alerted auditorally by the experimenter at the beginning of each trial, fixated the center cross, and then reported the center digit plus the word or words which appeared in the VHF%. While subjects were required to report the center digits first, the words on the bilateral trials could be reported in any order.

In the NC-V trials, subjects were requested to lixate the center cross as above. However, the stimulus card contained a slanted line at the center of fixation plus the VHF word(s). Subjects were asked to first select the slanted line from the answer card containing g choices and then report the VHF word(s).

For the NGN block of trials. subiects viewed the center f?xation cross. followed bv a stimulus card containing a slanted line at the center of fixation and a face or shape in one or’both VHF’s: On the unilateral trials, a single face or a shape was presented in one VHF; on the bilateral trials a face was presented in one VHF and a shape in the other. Subjects viewed the fixation cross and stimulus card, selected the slanted line from an answer card, and then picked the VHF shape or face from an answer sheet containing three choices. The answer sheets were grouped in a three ring binder. The subjects turned the page to expose the three choices for a given trial after identifying the slanted line for each trial. On the bilateral trials, there was a separate answer sheet for the shape stimulus and for the face stimulus. The order in which the answer sheets appeared on the bilateral trials was randomly alternated across VHF’s and type of stimulus with the constraint that each tvoe of stimulus was identified first an eoual number of times from the left and riaht __ VHF%..

On the VGN block of trials, each stimulus card contained a number at the fixation point and a face or shane in one or both VHF(s). Each unilateral trial stimulus contained one face or shane nlus the center number, while each bilateral~trial stimulus contained a face in one VHF and a shape in the other VHF. Subjects reported the center number first, then turned the page(s) in the answer booklet to select the face and,‘or shape presented.

Each subject received a total of 36 practice trials and 240 scored trials. The total session was usually completed within an hour.

596 DAWD HINES

RESULTS

The data were analyzed for the word, shape and face VHF stimuli. The null hypothesis was rejected for all statistical tests whenever P~0.05.

Thepercent of words correctly reported from each VHF as a function of center fixation is shown in Table 1. The word data were analyzed by analysis of variance with word type

Table 1. Percentage of words correct from each VHF as a function of verbal or nonverbal center stimuli

Visual-half-field Center stimuli Left Right Mean

Verbal 31.8 46.8 39.2 Nonverbal 34.9 48,2 41.6 Mean 33.3 47.5

(abstract-concrete), VHF, unilateral vs bilateral presentation, and type of center stimulus, as within group factors. As can be observed in Table 1, the type of center stimulus had little effect on either VHF asymmetry or overall recall, with neither the main effect of type of center stimuli nor the interaction between VHF and type of center control significant. The other main effects were significant, as would be expected from prior studies. Subjects recognized more words from the right VHF, PtO*Ol, as indicated in Table 1. More words were recognized under unilateral presentation (43.6 %) than bilateral presentation, P<O*Ol . Finally, as in previous studies [I 1, 121 more concrete words (42.8 %) were recognized than abstract words (38-O %); the difference was marginally significant, P~0.1. None of the interactions reached significance. As in previous studies, greater right VHF superiority was observed under bilateral than unilateral presentation; however, the interaction between VHF’s and unilateral-bilateral presentation was not statistically reliable, F-c 1, Similarly, there was a greater right VHF superiority for abstract than for concrete words, but again the difference was not statistically significant.

The data on face recognition was also analyzed using analysis of variance, with VHF’s, unilateral vs bilateral presentation, and type of center stimulus as within group factors. More faces were recognized from the left VHF, P<O*Ol, and when digits were used as center fixation stimuli, P ~0.01. These results can be observed in Table 2. In addition, more faces were recognized under unilateral (72.8 %) than bilateral (61.2 %) presentation, P-CO-01.

The interaction between VHFand type of center control approached significance, PtO-10.

This interaction can also be observed in Table 2. A larger left VHF superiority was observed for faces when the center stimulus was nonverbal. Thus the interaction is in the direction suggested by Kinsbourne’s attentional theory.

The data for shapes was also analyzed by analysis of variance with VHF, unilateral- bilateral presentation, and type of center stimulus as within group conditions. As shown in Table 3, more shapes were recognized under conditions of unilateral than bilateral presen- tation, P-CO-01. More shapes were recognized when a verbal center stimulus was presented, (P-CO-01). Slightly more shapes were recognized from the right VHF than the left VHF, however, the difference was not significant. The marginally significant unilateral-bilateral presentation x type of center stimulus interaction, PcO.1, is shown in Table 3. As can be observed the drop in recognition associated with the nonverbal center stimulus is larger under conditions of unilateral presentation.

The interaction between VHF and type of center stimuli is also shown in Table 3. The

VISUAL 1NFORMATION PROCESSINO IN THE LEFT AND RIOHT HEMISPHERES 597

Table 2. Percentage of faces correctly identified in each VHF as a function of verbal or nonverbal center stimuli

Visual-half-field Center stimuli Left Right Mean Verbal 768 70.8 73.8 Nonverbal 66.8 53.8 60.2 Mean 71.8 62.2

Table 3. Percentage of shapes correctly recognized from the left and right VHF as a function of center stimuli and unilateral - bilateral presentation

Center stimuli Unilateral Bilateral Left Right Mean Verbal 89.2 60.2 74.8 74.8 74.8 Nonverbal 66.5 49.2 55.0 60.8 57.9 Mean 77.9 54.8 64.9 67.8

direction was opposite that for faces with a right VHF superiority associated with non- verbal center stimuli. However, the interaction was not significant.

DISCUSSION

The results of this experiment indicate that VHF asymmetry is determined by the type of stimulus in the VHF rather than by type of center control stimulus, under the four common adult experimental paradigms. The results also demonstrate that the finding by Kershner et al. of a reversal in VHF asymmetry with verbal versus nonverbal center control stimuli does not generalize to the conditions of the present experiment.

This experiment found that each type of VHF stimuli had a characteristic pattern of right-left asymmetry, which was maintained regardless of which center stimuli was present- ed. The word stimuli were recognized most often from the right VHF, with the type of center fixation having no apparent effect on VHF asymmetry. The face stimuli were recognized more often from the left VHF; however, the left VHF superiority was larger on trials when a nonverbal center control stimulus was presented. The shape stimuli showed no reliable VHF asymmetry, although there tended to be a right VHF superiority on those trials with a nonverbal center stimulus.

These findings are quite similar to those in previous studies which have presented verbal and nonverbal VHF stimuli bilaterally on the same trials [4, 131. The right VHF superiority for words under various conditions of unilateral and bilateral presentation must rank as one of the most documented phenomena in the recent psychological literature. The size of the right VHF superiority was not significantly altered by changing the verbal-nonverbal nature of the center stimulus in the present study nor has it been significantly altered by randomly altering verbal and nonverbal stimuli in the VHF’s in previous studies using bilateral stimulation [4, 131. It seems evident from these findings that attentional set is at best a minor influence on right VHF asymmetry for words in the commonly used adult VHF experimental conditions. The left VHF superiority for face recognition has now been demonstrated in a number of studies [14-171. This condition in the present experiment did offer some tentative support for the hypothesis that type of center control stimuli can influence VHF asymmetry. KLEIN et al. [14] have also reported evidences that “verbal priming” decreases the left VHF superiority for faces under bilateral presentation. Finally, the neglible VHF asymmetry for shapes suggests the complex nature of this task. HELLIGE

598 DAVID HINES

and Cox [18] have reported a rather complex relationship between VHF asymmetry and verbal memory load for unilaterally presented shapes.

The lower recognition for the faces and shapes when a nonverbal center stimulus was presented probably reflects the difficulty of the angle identification task; only 49% of the center angles were correctly identified by the subjects (chance=12*5%). Recognition of nonverbal stimuli is reduced by a difficult competing task [19,20]. Thus the need to closely attend the center angle apparently reduced recognition of the nonverbal VHF stimuli, even though it had no consistent effect on their left-right asymmetry.

Priming and overload efects While Kinsbourne’s attentional theory of VHF asymmetry [2] was originally presented

as an alternative to Kimura’s “anatomical” model [3], the major experimental findings that have resulted are quite consistent with the hypothesis that VHF asymmetry reflects the information processing capacity of the two cerebral hemispheres. It has been shown that neither the right VHF superiority for words or left VHF superiority for faces are due to attentional factors, since both can be found when the words and faces are presented simultaneously [13, 141. The present experiment has also demonstrated that the right VHF asymmetry for words cannot be attributed to using a verbal fixation control stimulus.

Two effects suggested by Kinsbourne have been demonstrated: A “priming” or “acti- vating” effect when a particular hemisphere is aroused and an “overload” effect when a particular hemisphere has to do more than one task concurrently [21]. The “priming” effect increases the efficiency of a particular hemisphere for VHF recognition, while the overload effect reduces hemispheric accuracy for VHF recognition. For example, HELLIGE and Cox [ 181 found that an easy verbal memory load improved performance from the right VHF-left hemisphere (priming effort) while a more different verbal memory load decreased VHF recognition from the right VHF (overload effort). Neither memory load affected recognition of random shapes from the left VHF-right hemisphere. Kinsbourne had suggested that the priming effect might be due to a shift of attention (and in some conditions eye movements) to the VHF contralateral to the activated hemisphere. However, this would imply a change in left VHF recognition as well as a change in right VHF recognition. Instead Hellige and Cox found left VHF-right hemisphere recognition was independent of the verbal memory load. Thus the priming and overload effects seem to modify the infor- mation processing capacity of a particular hemisphere (and the VHF recognition from the contralateral VHF) independently of the other.

In conclusion the present experiment has demonstrated that VHF asymmetry in adults is not consistently altered by use of either a verbal or nonverbal center fixation stimulus. There are a number of differences between this experiment and the Kershner et al. study which reported that VHF asymmetry was significantly altered by type of center stimulus. However, the conditions of the present experiment were representative of those in the majority of tachistoscopic VHF studies in the recent experimental literature.

This study supports the hypothesis that VHF asymmetry reflects the information processing capacity of the two cerebral hemispheres. It is not inconsistent with the hypo- thesis that “priming or overload” efforts can alter the functioning of a particular cerebral hemisphere. However, the findings are inconsistent with Kinsbourne’s hypothesis that VHF asymmetry can be accounted for by attentional factors.

VISUAL INFORMATION PROCESSING IN THE LF.m AND RIGHT HEMISPHERES 599

REFERENCES

1. KKRSHNER, J., TOMAE, R. and CALLAWAY, R. Nonverbal fixation control in young children induces a left-field advantage in digit recall. Neuropsychologia 15,569-576, 1977

2. KINSBOURNE, M. Cerebral basis of asymmetry in attention. Acta. Psychof. 33, 193-201,197O. 3. KIMJRA, D. Dual functional asymmetry of the brain in visual perception. Neuropsychologia 4,278-285,

1966. 4. HINES, D. Independent functioning of the two cerebra1 hemispheres for recognizing bilaterally presented

tachistoscopic visual-half-field stimuli. Corfex 11, 132-143, 1975. 5. GILL, K. M. and MCKEEVER, W. F. Word length and exposure time effects on the recognition of

bilaterally presented words. Bull. Psychonomic. Sot. 4, 173-175, 1974. 6. FONTENOT, D. J. and BENTON, A. L. Perception of direction in the right and left visual fields. Neuro-

psychologia 10, 447452, 1972. 7. UMILTA, C., RIZZOLATTI, G., MARZI, C. A., ZAMBONI, G., FRANZINI, C., CAMARDA, R. and BERLUCCHI,

G. Hemispheric differences in the discrimination of line orientation. Neuropsychologia 12,165-174,1974. 8. SPREEN, 0. and SCHULTZ, R. W. Parameten of abstraction, meaningfulness, and pronouncibility for

329 nouns. J. verb. Learn. verb. Behav. 5,459468, 1968. 9. THORNDIKE, E. L. and LORGE, I. The Teaching Word Book of30,OOO Words. Teaching College Bureau

of Publications, New York, 1974. 10. BROWN, D. R. and OWEN, D. H. The metrics of visual form: methodological dyspepsia. Psychol Bull.

68,243-259, 1967. 11. HINES, D. Differences in tachistoscopic recognition between abstract and concrete words as a function

of visual-half-field and frequency. Cortex 13, 66-73, 1977. 12. 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. 13. P~OZZOLO, F. J. and RAYNOR, K. Hemispheric specialization in reading and word recognition. Brain &

Lang. 4,248-261, 1977. 14. KLEIN, D., MOSC~~ITCH, M. and VIGNA, C. Attentional mechanisms and perceptual asymmetries in

tachistoscopic recognition of words and faces. Neuropsychologia 14, 55-66, 1976. 15. MARCEL, T. and RAJAN, P. Lateral specialization for recognition of words and faces in good and poor

readers. Neuropsychologia 13,489-497, 1975. 16. HILLIARD, R. D. Hemispheric laterality effects on a facial recognition in normal subjects. Cortex 9,

246258, 1973. 17. ELLIS, H. D. and SHEPHERD, J. W. Recognition of upright and inverted faces presented in the left and

right visual fields. Cortex 11, 3-7, 1975. 18. HELLIGE, J. B. and Cox, P, J. Effects of concurrent verbal memory on recognition of stimuli from the

left and right visual fields. J. exp. Psychol.: Human Percept. Perform. 2,210-221, 1976. 19. HINES, D. and SMITH, S. Recognition of random shapes followed at varying delays by attended or

unattended shapes, digits, and line grids. J. exp. Psychol. : Human Learn. Memory 3, 29-36, 1977. 20. HINES, D. Task difficulty and visual similarity increase a distractor’s effects on random shapes. Percepf.

Mot. Skills 46, 235-248, 1978. 21. HICKS, R. E. Tntrahemispheric response competition between vocal and unimanual performance in

normal adult human males. J. camp. physiol. Psycho!. 89, 50-60, 1975.

600 DAVID HINES

Rds”me :

En utilisant des stinulus a la fois verbaux et non verbaux dans chaque hemichamp, on a Btudie l'effet sur l'asymetrie des h&i-

champs, des stimulus au point de fixation salon qu'ils etaient verbaux

ou non verbaux. On a donne a 20 sujets adultes des stimulus mots, vi-

sages et formes aleatoires sous des conditions de vision unilaterale

et bilaterale.

Les resultats montraient que l'asymetrie des champs visuels

dtait essentiellement ddterminee par le type de stimulus dans chaque

champ sous toutes les conditions de vision. Les mots Btaient reconnus plus souvent dans le champ visuel droit, les visages plus souvent dans

le champ visuel gauche et pour les formes aleatoires, aucune difference

significative etait not&. Ces resultats indiquent qua l'asymetrie

des hemichamps visuels temoigne des differences dans la capacite de

traitement de l'information entre les hemispheres droit et gauche.

Deutschsprachige Zusammenfassung:

Es wurde die Auswirkung eines sprachlichen im Vergleich zu

einem nichtsprachlichen Stimulus als zentralem Fixationspunkt

auf eine visuelle Halbfeld (VHF)- Asymmetric untersucht, in-

dem sowohl sprachliche wie nichtsprachliche VHF-Stimuli ver-

wandt wurden. 20 erwachsene Probanden wurde ein Wort-, Ge-

sichts- und Zufallsformen-VHF-Reizmaterial angeboten, und

zwar sowohl unter unilateralen wie bilateralen Sehbedingun-

gen.

Die Ergebnisse zeigten, da0 eine VHF-Asymmetric unter allen

Sehbedingungen bestimmt wird durch den Typ des VHF-Stimulus.

Warter wurden 8fter in der rechten Gesichtsfeldhalfte er-

kannt, Gesichter ijfter in der linken GesichtsfeldhXfte, und

Zufallsformen zeigten keinen signifikanten VHF-Unterschied.

Die Ergebnisse zeigen an, daf3 eine VHF-Asymmetric Unterschie-

de der Informationsverarbeitungsfahigkeit zwischen linker _

und rechter Hemisphdre widerspiegelt.