Neuropsychologia.
1975, Vol. 13, pp. 377 to 381. Pergamon Press. Printed in England
NOTE PARALLEL-SERIAL
PROCESSING
AND
HEMISPHERIC
FUNCTION*
MURRAYJ. WHITE and K. GEOFFREYWHITE Victoria University of Wellington, Wellington, New Zealand (Received
25 February
1975)
Abstrad-In one experiment 14 subjects made same-different responses to geometric forms varying in number from two to four, and presented randomly in the left or right visual hemifields. In a second experiment two different groups of subjects (N, = N2 = 6) responded to letters, varying in number from two to four which could be matched on either nominal or physical identity. In both experiments reaction times were faster for stimuli directed to the right hemisphere and in no condition did reaction times increase with increasing number of stimuli. Implications for a relationship between mode of processing and hemispheric function were discussed.
INTRODUCTION STIMULIwhich can readily be matched through common physical properties show faster reaction times when directed to the right than to the left hemisphere. Stimuli which can be matched only on a common nominal basis show faster reaction times when directed to the left than to the right hemisphere [I, 21. Physical-spatial and nominal-verbal matchings also appear related to whether matches are made in parallel or serially [3]. COHEN [l] has suggested that a relationship might exist between hemispheric function and mode of processing such that the left hemisphere processes in serial and the right hemisphere processes in parallel. From the results of three experiments she concluded: “It is probable therefore that hemispheric differences in serial vs parallel processing are limited to tasks like the matching of alphanumeric stimuli or words, which can be performed either verbally or visuospatially [I, p. 3551.” The present experiments extend Cohen’s investigations by examining hemispheric asymmetries in serialparallel processing for geometric shapes, and for sets of letters which are either physically identical (e.g., AAA) or physically different and nominally identical (e.g., AAa). It was predicted that geometric forms and physically-identical letters would show similar processing characteristics (in parallel), and these would be dissimilar from those for nominally-identical letters (serially). This prediction was based on findings that hemispheric asymmetries are more sensitive to the type of processing than to the type of stimulus. The present experiments were also intended to improve on Cohen’s methodology, in particular on the use of one hand for making same responses and on the other hand for making different responses.
EXPERIMENT
1. METHOD
Subjects Six women and eight men served as subjects. All were right-handed,
had no obvious visual defects, and
each was paid $2 for participation.
Stimuli consisted of combinations of 2 or 3 or 4 geometric forms mounted on 4 x 6 in. tachistocope cards. Sixty experimental and 6 practice cards were prepared. On the 60 experimental cards, 20 showed two forms, 20 three forms, and 20 four forms. Within each of these sets of 20, 10 cards showed the forms in the left field and 10 in the right field. Five of each of these subsets of 10 showed combinations of the same stimulus (e.g., 3 circles) and 5 showed combinations of different stimuli (e.g., 1 circle and 2 triangles). The stimuli were: black filled-in circle, triangle, star, square, and half-moon. Five patterns were arranged for each of the 2, 3, and 4 size size sets. Each pattern was used once in a “same” stimulus arrangement and once in a “different” arrangement. Also, a pattern shown in the left field was, at some stage, shown in the right field. For the 30 different cards, each stimulus form was used equally often in the 2, 3, and 4 size sets and equally often in the left and right field. Procedure
The 60 experimental cards, preceded by the 6 practice cards, were presented to subjects in a fixed random order in 2 experimental sessions. Two reaction time keys each consisted of 2 thin phosphor-bronze strips mounted laterally on a perspex base with the strips separated by perspex walls, between which the subject 377
NOTE
378
placed his first and middle fingers. The subject fixated the pre-exposure field light dot when the experimenter said “read?: this dot remained on for 1 set and was immediately followed bv a stimulus exnosure of 120 msec. The-pre-exposure and post-exposure fields of the tachistoscope (Gerbrands Model Tl3B-1C) were dark and the stimulus field background was 7 cd/m*. With 7 of the 14 subjects, both index fingers were indicated for same responses and both middle fingers for different responses; for 7 subjects both index fingers were indicated for different responses and both middle fingers for same responses. Subjects were instructed to fixate the pre-exposure light dot and to rapidly press both index (or both middle) fingers if a card showed 2 or 3 or 4 forms which were identical, and to press both middle (or both index) fingers if a card showed 2, or 3, or 4 forms where one form was different from the rest. Subjects kept the same finger-response combination in both sessions. Following each trial, the subject was told whether or not his response was correct and his reaction time. Viewing was binocular.
RESULTS The results are summarized in Table I. Analysis of reaction times (Subjects x Response :i Hemisphere .’ Set Size) showed Hemisphere to be significant (F = 4.99; df = l/13; P < 0.05). Mean reaction times for forms directed to the left hemisphere was 574 msec and for forms directed to the right hemisphere, 562 msec. Ten of the 14 subjects showed faster reaction times for right hemisphere presentations and one subject showed equally fast times for left and right hemisphere presentations. The interaction between Hemisphere and Set Size was not significant (F < 1). A comparison of reaction times for first and middle lingers showed no finger effects in speed of responding (t = I .44). Analysis of errors, responding same for different forms and different for same forms, again showed Hemisphere to be significant (F = 5.52, df = l/13, P < 0.05). Mean errors committed for left and right hemisphere presentations were 15.6% and 12.1 0/Orespectively. Ten of the 14 subjects showed fewer errors for right hemisphere presentations. The Hemisphere Y Set Size interaction for errors was not significant (F < 1). Table 1. Mean reaction times (msec) and errors (%) for forms shown to left and right hemispheres (LH, RH) same responses
Reaction times EITGrS
Uiff. responses
LH
RH
I."
RH
585
560
563
564
16.7
15.7
14.5
8.6
EXPERIMENT
2. M ETHOD
Subjects
Two women and 4 men served in one condition (P) and 6 men served in another condition (N). Subjects were assigned at random to P and N conditions. None had served in Experiment I, all were right-handed and free of obvious visual defects, and each was paid 82 for participation. Stimuli
Stimuli consisted of combinations of 2 or 3 or 4 letters (Lctraset No. 372) mounted on 4 x 6 in. tachistoscope cards. Ninety-six experimental and 6 practice cards were prepared for the N condition and a similar number for the P condition. Within each condition, 32 cards showed two letters, 32 three letters, and 32 four letters. Sixteen of each of these 32 cards showed letters which were nominally identical but physically different, e.g., Aa, Nnn, GGGg (N condition); 16 showed letters which were nominally and physically identical, e.g., AA, nnn, gggg (P condition). The remaining 16 cards showed letters which were nominally and physically different. E.g., An, Nng, GGAg, in the N condition; EA, nng, ggga, in the P condition. Eight of each of the 16 card subsets had letters mounted in the left field and eight had letters mounted in the right field. Each pattern in the 2 and 3 and 4 size sets was used equally often for same and different arrangements and for left and right arrangements. Procedure
The procedure and apparatus were similar to the procedure and apparatus in Experiment 1. Response fingers were matched with same and different cards as in Experiment 1. In the N condition, subjects were
NOTE
instructed to respond “same” whenever a card having “different” whenever a card having letters of different instructed to respond “same” whenever a card showing and “different” whenever a card showing letters which
379
letters of the same name was shown and to respond names was shown. In the P condition subjects were letters having the same physical structure was shown were physically different was shown.
RESULTS The results are summarized in Table 2. Analysis of the reaction times (Subjects x Match Condition x Response x Hemisphere x Set Size) showed the following: (1) Reaction times in the P condition were faster than reaction times in the N condition (F = 8.38, df = l/10, P < 0.025). (2) Same responses were faster than different responses (F = 5.06, df = l/10, P -c 0.05). There were no effects due to finger-response combination. Mean reaction time for index fingers was 624 msec and for middle fingers 618 msec (I = 0.35). (3) The interaction between Match Condition and Response was significant (F = 7.72, df = l/10, P < 0.025). In the P condition, same responses were faster than different responses by a mean of 57 msec; in the N condition, different responses were faster than same responses by a mean of 7 msec. (4) The main effect of Hemisphere was not significant (F = 1.01) but nine of the 12 subjects showed faster reaction times for right hemisphere presentations, and one subject showed equally fast reaction times for left and right hemisphere presentations. The failure to reach significance was due to one subject in the N condition who had a mean of 803 msec for right hemisphere and a mean of 757 msec for left hemisphere presentations. (5) The triple Response x Hemisphere x Set Size interaction was significant (F = 4.90, df = 2/20, P < 0.025). This is shown in Table 3. Table 2. Mean reaction times (msec) and errors (%) for letters shown to left and right hemispheres (LH, RI-I) for P and N conditions Diff. responses
Same responses
LH
LH
Rli
RR
P condition Reaction times ElTOlX
545
535
595
600
18.1
22.9
14.6
20.8
N condition Reaction times Errors
680
655
662
661
24.3
24.9
20.8
16.0
Table 3. Mean reaction times (msec) for letters shown to left and right hemispheres (LH, RH) for 2-, 3-, or 4-size letter responses Same responses
Letter size
LH
RH
2
614
577
3
605 617
4
A preliminary examination formed on these results.
LH-RR
Diff.
responses
LH
RR
+37
627
643
-16
623
-18
6i4
632
-L12
585
C32
614
617
- 3
LH-RH
of the error results showed no observable effects and no analysis was per-
NOTE
380
DISCUSSION The absence of significant interactions between Hemisphere and Set Size suggests that both hemispheres process spatial and verbal stimuli in parallel. This is, however, equivalent to accepting null hypothesis evidence: if reaction times increase with increasing set size then a parallel process is not indicated; if reaction times do not increase then a parallel process is indicated. But if the present experiments (minimizing response asymmetry) are looked at in relation to COHEN’Sexperiments [l] (where response asymmetry might well have accounted for the right hemisphere effects in Experiments 1 and II), no clear-cut results are apparent, linking mode of processing to hemispheric function. Cohen observed same reaction times to increase with increasing set size for letters directed to the left hemisphere but to decrease for letters directed to the right hemisphere. Given that complex configurations are handled better by the right hemisphere in an integrative fashion [4], it is not clear why same reaction times for shapes directed to the right hemisphere did not decrease with increasing set size. Curiously, Cohen observed same reaction times for shapes directed to the left hemisphere decreased with increasing set size. The present finding of faster overall reaction times for stimuli directed to the right hemisphere might indicate, at least for the present configurations, stimuli were being matched on their physical characteristics. To be consistent with earlier findings [1,2], showing faster left hemisphere reaction times for letters matched on nominal identity, two-size letter sets in the N condition should have shown faster left hemisphere times. An explanation for this inconsistency in results is seen in the triple interaction shown in Table 3. For set sizes of 2 and 4 letters, same responses were faster for right hemisphere presentations; for set sizes of 3 letters, same responses were faster for left hemisphere presentations. The results for different responses were opposite, if not as clear-cut. This suggests, that in the present experiment, the Hemisphere effect was somehow tied-up with response and pattern configuration effects which preempted any effects due to matching task. In turn, this suggests a hypothesis that the hemispheres are differentially sensitive to gestalt configuration even when response asymmetry is minimized by having both hands make a single response. Acknowledgements-This work was supported Thanks are due to AL SILVERfor assistance.
by Grant 52/73 from Victoria University
of Wellington.
REFERENCES 1. COHEN, G. Hemispheric differences in serial versus parallel processing. J. exp. Psychol. 97, 349-356, 1972. 2. GEFFEN. G., BRADSHAW,J. L. and NETTLETON.N. C. Hemisnheric asvmmetrv: Verbal and snatial encoding of visual stimuli.‘J. exp. Psycho/. 95, 25131, 1972. . _ _ 3. BELLER, H. K. Parallel and serial stages in matching. J. exp. Psycho/. 84, 213-219, 1970. 4. LEVY-AGRESTI, J. and SPERRY, R. W. Differential capacities in major and minor hemispheres. Proc. N.A.S. 61, 1151, 1968.
NOTE
381
Zusammenfassung
In einem Experiment wurden wahllos geonetrische ii.gyren
in
der rechten und linken Gesichtafeldhllfteirgeboten, deren Zahl zwischen 2 und 4 variierte. 14 Versuchspersonen gaben dabei ahnlich unterschledllche Antvorten. 3ei einec zxeiten Experiment reegierten 2 verschiedene Gruppen van lTersuchspersonen ("1,= 142= 6) auf die Barbietung van 3uchstaber., deren Anzahl ebenfalls zvischen 2 und b la&~,entveder so, daR sic diese nor,inaloder rYu~~lic!: zuordseten. 3ei beider Sxperimenten wezen die Leaktionsbreiten bei Etiruli Wrzer, die der rechten Hemisphlre entsprache::.Lnter keiner 3edlngung stiegen die Reaktionszeiten bei zunehmender Feizzahl an. Es wurden 3eziehungen zwischen Vorgehenweise und henisphlT rischer Mktion dlskutiert.
1975, Vol. 13, pp. 377 to 381. Pergamon Press. Printed in England
NOTE PARALLEL-SERIAL
PROCESSING
AND
HEMISPHERIC
FUNCTION*
MURRAYJ. WHITE and K. GEOFFREYWHITE Victoria University of Wellington, Wellington, New Zealand (Received
25 February
1975)
Abstrad-In one experiment 14 subjects made same-different responses to geometric forms varying in number from two to four, and presented randomly in the left or right visual hemifields. In a second experiment two different groups of subjects (N, = N2 = 6) responded to letters, varying in number from two to four which could be matched on either nominal or physical identity. In both experiments reaction times were faster for stimuli directed to the right hemisphere and in no condition did reaction times increase with increasing number of stimuli. Implications for a relationship between mode of processing and hemispheric function were discussed.
INTRODUCTION STIMULIwhich can readily be matched through common physical properties show faster reaction times when directed to the right than to the left hemisphere. Stimuli which can be matched only on a common nominal basis show faster reaction times when directed to the left than to the right hemisphere [I, 21. Physical-spatial and nominal-verbal matchings also appear related to whether matches are made in parallel or serially [3]. COHEN [l] has suggested that a relationship might exist between hemispheric function and mode of processing such that the left hemisphere processes in serial and the right hemisphere processes in parallel. From the results of three experiments she concluded: “It is probable therefore that hemispheric differences in serial vs parallel processing are limited to tasks like the matching of alphanumeric stimuli or words, which can be performed either verbally or visuospatially [I, p. 3551.” The present experiments extend Cohen’s investigations by examining hemispheric asymmetries in serialparallel processing for geometric shapes, and for sets of letters which are either physically identical (e.g., AAA) or physically different and nominally identical (e.g., AAa). It was predicted that geometric forms and physically-identical letters would show similar processing characteristics (in parallel), and these would be dissimilar from those for nominally-identical letters (serially). This prediction was based on findings that hemispheric asymmetries are more sensitive to the type of processing than to the type of stimulus. The present experiments were also intended to improve on Cohen’s methodology, in particular on the use of one hand for making same responses and on the other hand for making different responses.
EXPERIMENT
1. METHOD
Subjects Six women and eight men served as subjects. All were right-handed,
had no obvious visual defects, and
each was paid $2 for participation.
Stimuli consisted of combinations of 2 or 3 or 4 geometric forms mounted on 4 x 6 in. tachistocope cards. Sixty experimental and 6 practice cards were prepared. On the 60 experimental cards, 20 showed two forms, 20 three forms, and 20 four forms. Within each of these sets of 20, 10 cards showed the forms in the left field and 10 in the right field. Five of each of these subsets of 10 showed combinations of the same stimulus (e.g., 3 circles) and 5 showed combinations of different stimuli (e.g., 1 circle and 2 triangles). The stimuli were: black filled-in circle, triangle, star, square, and half-moon. Five patterns were arranged for each of the 2, 3, and 4 size size sets. Each pattern was used once in a “same” stimulus arrangement and once in a “different” arrangement. Also, a pattern shown in the left field was, at some stage, shown in the right field. For the 30 different cards, each stimulus form was used equally often in the 2, 3, and 4 size sets and equally often in the left and right field. Procedure
The 60 experimental cards, preceded by the 6 practice cards, were presented to subjects in a fixed random order in 2 experimental sessions. Two reaction time keys each consisted of 2 thin phosphor-bronze strips mounted laterally on a perspex base with the strips separated by perspex walls, between which the subject 377
NOTE
378
placed his first and middle fingers. The subject fixated the pre-exposure field light dot when the experimenter said “read?: this dot remained on for 1 set and was immediately followed bv a stimulus exnosure of 120 msec. The-pre-exposure and post-exposure fields of the tachistoscope (Gerbrands Model Tl3B-1C) were dark and the stimulus field background was 7 cd/m*. With 7 of the 14 subjects, both index fingers were indicated for same responses and both middle fingers for different responses; for 7 subjects both index fingers were indicated for different responses and both middle fingers for same responses. Subjects were instructed to fixate the pre-exposure light dot and to rapidly press both index (or both middle) fingers if a card showed 2 or 3 or 4 forms which were identical, and to press both middle (or both index) fingers if a card showed 2, or 3, or 4 forms where one form was different from the rest. Subjects kept the same finger-response combination in both sessions. Following each trial, the subject was told whether or not his response was correct and his reaction time. Viewing was binocular.
RESULTS The results are summarized in Table I. Analysis of reaction times (Subjects x Response :i Hemisphere .’ Set Size) showed Hemisphere to be significant (F = 4.99; df = l/13; P < 0.05). Mean reaction times for forms directed to the left hemisphere was 574 msec and for forms directed to the right hemisphere, 562 msec. Ten of the 14 subjects showed faster reaction times for right hemisphere presentations and one subject showed equally fast times for left and right hemisphere presentations. The interaction between Hemisphere and Set Size was not significant (F < 1). A comparison of reaction times for first and middle lingers showed no finger effects in speed of responding (t = I .44). Analysis of errors, responding same for different forms and different for same forms, again showed Hemisphere to be significant (F = 5.52, df = l/13, P < 0.05). Mean errors committed for left and right hemisphere presentations were 15.6% and 12.1 0/Orespectively. Ten of the 14 subjects showed fewer errors for right hemisphere presentations. The Hemisphere Y Set Size interaction for errors was not significant (F < 1). Table 1. Mean reaction times (msec) and errors (%) for forms shown to left and right hemispheres (LH, RH) same responses
Reaction times EITGrS
Uiff. responses
LH
RH
I."
RH
585
560
563
564
16.7
15.7
14.5
8.6
EXPERIMENT
2. M ETHOD
Subjects
Two women and 4 men served in one condition (P) and 6 men served in another condition (N). Subjects were assigned at random to P and N conditions. None had served in Experiment I, all were right-handed and free of obvious visual defects, and each was paid 82 for participation. Stimuli
Stimuli consisted of combinations of 2 or 3 or 4 letters (Lctraset No. 372) mounted on 4 x 6 in. tachistoscope cards. Ninety-six experimental and 6 practice cards were prepared for the N condition and a similar number for the P condition. Within each condition, 32 cards showed two letters, 32 three letters, and 32 four letters. Sixteen of each of these 32 cards showed letters which were nominally identical but physically different, e.g., Aa, Nnn, GGGg (N condition); 16 showed letters which were nominally and physically identical, e.g., AA, nnn, gggg (P condition). The remaining 16 cards showed letters which were nominally and physically different. E.g., An, Nng, GGAg, in the N condition; EA, nng, ggga, in the P condition. Eight of each of the 16 card subsets had letters mounted in the left field and eight had letters mounted in the right field. Each pattern in the 2 and 3 and 4 size sets was used equally often for same and different arrangements and for left and right arrangements. Procedure
The procedure and apparatus were similar to the procedure and apparatus in Experiment 1. Response fingers were matched with same and different cards as in Experiment 1. In the N condition, subjects were
NOTE
instructed to respond “same” whenever a card having “different” whenever a card having letters of different instructed to respond “same” whenever a card showing and “different” whenever a card showing letters which
379
letters of the same name was shown and to respond names was shown. In the P condition subjects were letters having the same physical structure was shown were physically different was shown.
RESULTS The results are summarized in Table 2. Analysis of the reaction times (Subjects x Match Condition x Response x Hemisphere x Set Size) showed the following: (1) Reaction times in the P condition were faster than reaction times in the N condition (F = 8.38, df = l/10, P < 0.025). (2) Same responses were faster than different responses (F = 5.06, df = l/10, P -c 0.05). There were no effects due to finger-response combination. Mean reaction time for index fingers was 624 msec and for middle fingers 618 msec (I = 0.35). (3) The interaction between Match Condition and Response was significant (F = 7.72, df = l/10, P < 0.025). In the P condition, same responses were faster than different responses by a mean of 57 msec; in the N condition, different responses were faster than same responses by a mean of 7 msec. (4) The main effect of Hemisphere was not significant (F = 1.01) but nine of the 12 subjects showed faster reaction times for right hemisphere presentations, and one subject showed equally fast reaction times for left and right hemisphere presentations. The failure to reach significance was due to one subject in the N condition who had a mean of 803 msec for right hemisphere and a mean of 757 msec for left hemisphere presentations. (5) The triple Response x Hemisphere x Set Size interaction was significant (F = 4.90, df = 2/20, P < 0.025). This is shown in Table 3. Table 2. Mean reaction times (msec) and errors (%) for letters shown to left and right hemispheres (LH, RI-I) for P and N conditions Diff. responses
Same responses
LH
LH
Rli
RR
P condition Reaction times ElTOlX
545
535
595
600
18.1
22.9
14.6
20.8
N condition Reaction times Errors
680
655
662
661
24.3
24.9
20.8
16.0
Table 3. Mean reaction times (msec) for letters shown to left and right hemispheres (LH, RH) for 2-, 3-, or 4-size letter responses Same responses
Letter size
LH
RH
2
614
577
3
605 617
4
A preliminary examination formed on these results.
LH-RR
Diff.
responses
LH
RR
+37
627
643
-16
623
-18
6i4
632
-L12
585
C32
614
617
- 3
LH-RH
of the error results showed no observable effects and no analysis was per-
NOTE
380
DISCUSSION The absence of significant interactions between Hemisphere and Set Size suggests that both hemispheres process spatial and verbal stimuli in parallel. This is, however, equivalent to accepting null hypothesis evidence: if reaction times increase with increasing set size then a parallel process is not indicated; if reaction times do not increase then a parallel process is indicated. But if the present experiments (minimizing response asymmetry) are looked at in relation to COHEN’Sexperiments [l] (where response asymmetry might well have accounted for the right hemisphere effects in Experiments 1 and II), no clear-cut results are apparent, linking mode of processing to hemispheric function. Cohen observed same reaction times to increase with increasing set size for letters directed to the left hemisphere but to decrease for letters directed to the right hemisphere. Given that complex configurations are handled better by the right hemisphere in an integrative fashion [4], it is not clear why same reaction times for shapes directed to the right hemisphere did not decrease with increasing set size. Curiously, Cohen observed same reaction times for shapes directed to the left hemisphere decreased with increasing set size. The present finding of faster overall reaction times for stimuli directed to the right hemisphere might indicate, at least for the present configurations, stimuli were being matched on their physical characteristics. To be consistent with earlier findings [1,2], showing faster left hemisphere reaction times for letters matched on nominal identity, two-size letter sets in the N condition should have shown faster left hemisphere times. An explanation for this inconsistency in results is seen in the triple interaction shown in Table 3. For set sizes of 2 and 4 letters, same responses were faster for right hemisphere presentations; for set sizes of 3 letters, same responses were faster for left hemisphere presentations. The results for different responses were opposite, if not as clear-cut. This suggests, that in the present experiment, the Hemisphere effect was somehow tied-up with response and pattern configuration effects which preempted any effects due to matching task. In turn, this suggests a hypothesis that the hemispheres are differentially sensitive to gestalt configuration even when response asymmetry is minimized by having both hands make a single response. Acknowledgements-This work was supported Thanks are due to AL SILVERfor assistance.
by Grant 52/73 from Victoria University
of Wellington.
REFERENCES 1. COHEN, G. Hemispheric differences in serial versus parallel processing. J. exp. Psychol. 97, 349-356, 1972. 2. GEFFEN. G., BRADSHAW,J. L. and NETTLETON.N. C. Hemisnheric asvmmetrv: Verbal and snatial encoding of visual stimuli.‘J. exp. Psycho/. 95, 25131, 1972. . _ _ 3. BELLER, H. K. Parallel and serial stages in matching. J. exp. Psycho/. 84, 213-219, 1970. 4. LEVY-AGRESTI, J. and SPERRY, R. W. Differential capacities in major and minor hemispheres. Proc. N.A.S. 61, 1151, 1968.
NOTE
381
Zusammenfassung
In einem Experiment wurden wahllos geonetrische ii.gyren
in
der rechten und linken Gesichtafeldhllfteirgeboten, deren Zahl zwischen 2 und 4 variierte. 14 Versuchspersonen gaben dabei ahnlich unterschledllche Antvorten. 3ei einec zxeiten Experiment reegierten 2 verschiedene Gruppen van lTersuchspersonen ("1,= 142= 6) auf die Barbietung van 3uchstaber., deren Anzahl ebenfalls zvischen 2 und b la&~,entveder so, daR sic diese nor,inaloder rYu~~lic!: zuordseten. 3ei beider Sxperimenten wezen die Leaktionsbreiten bei Etiruli Wrzer, die der rechten Hemisphlre entsprache::.Lnter keiner 3edlngung stiegen die Reaktionszeiten bei zunehmender Feizzahl an. Es wurden 3eziehungen zwischen Vorgehenweise und henisphlT rischer Mktion dlskutiert.
