Cognitive abilities and left-handedness: An interaction between familial sinistrality and strength of handedness

The present study demonstrates that there are substantial differences in cognitive ability between different subsets of left-handers. The verbal and mathematical Scholastic Aptitude Test (SAT) scores of 86 left-handed undergraduates were examined as a function of familial sinistrality, strength of left-handedness, and sex. The results revealed that there was an interaction between familial sinistrality and strength of handedness in terms of aptitude: for the weakly to moderately left-handed there was no relationship between familial sinistrality and performance, whereas for the strongly left-handed a positive history of familial sinistrality (FS+) was associated with significantly lower aptitude when compared with subjects without a history of familial sinistrality (FS−). In addition, the strongly left-handed FS− group was superior to the other three groups, particularly in verbal aptitude.     

The roles of stimulus repetition and hemispheric activation in visual half-field asymmetries

Hardyck, Tzeng, and Wang (1978, Brain and Language, 5, 56–71) hypothesized that ample repetition of a small number of stimuli is required in order to obtain VHF differences in tachistoscopic tasks. Four experiments, with varied levels of repetition, were conducted to test this hypothesis. Three experiments utilized the general task of object-picture naming and one utilized a word-naming task. Naming latencies constituted the dependent measure. The results demonstrate that for the object-naming paradigm repetition is required for RVF superiority to emerge. Repetition was found to be unnecessary for RVF superiority in the word-naming paradigm, with repetition actually reducing RVF superiority. Experiment I suggested the possibility that RVF superiority developed for the second half of the trials as a function of practice or hemispheric activation, regardless of repetition level. Subsequent experiments, better designed to assess this possibility, clearly refuted it. It was concluded that the effect of repetition depends on the processing requirements of the task. We propose that, for tasks which can be processed efficiently by one hemisphere, the effect of repetition will be to reduce VHF asymmetries; but tasks requiring substantial processing by both hemispheres will show shifts to RVF superiority as a function of repetition.     

Right-hemisphere superiority for discriminating memorized from nonmemorized faces: Affective imagery, sex, and perceived emotionality effects

Sixty-four subjects, divided into four groups according to sex and type of memorization instruction, were given a manual RT task requiring discrimination of two memorized from two nonmemorized faces. Two types of memorization were employed, one emphasizing highly negative affective imagery about the faces being memorized (extreme sadness), the other relatively neutral imagery (feeling composed). Females in the affective imagery group were predicted to show left-visual-field superiority (LVFS), while females employing neutral imagery were not. Males were predicted to show LVFS regardless of imagery type because of their presumed strong right-hemispheric dominance for visual-spatial functions. Predictions were accurate for females; neither group of males showed significant LVFS. Post-experimental semantic differential ratings of the emotionality of the memorized faces showed that LVFS existed for faces rated as emotional, but not for faces rated as nonemotional. This effect was common to the sexes. Results indicate that right-hemispheric memory storage of faces can be induced in females through affective imagery and in both sexes via idiosyncratically perceived emotionality in the face stimuli. This effect of affectivity cannot be attributed to visual-spatial dominannce of the right hemisphere.     

Unilateral versus bilateral presentation methods in the reaction time paradigm

The use of bilateral presentation in lateralized tachistoscopic reaction time (RT) tasks has been precluded by problems of how to instruct the subject to respond to the left visual field (LVF) or right visual field (RVF) stimulus and by the necessity of fixation control with bilateral presentation. Schmuller and Goodman, 1979 and Schmuller and Goodman, 1980, Brain and Language, 11, 12–18) offered a method, applied to date only in recognition accuracy studies, which can overcome these problems. They used an “arrowhead pointer” at fixation. This instructs the subject as to which stimulus to report first and also controls fixation. We adapted the method to the RT paradigm by having subjects report only the stimulus indicated and applied it in a bilateral presentation version of the Object Naming Latency Task (W. F. McKeever & T. L. Jackson, 1979, Brain and Language, 7, 175–190). Fifty subjects received the unilateral task and 50 received the bilateral task. The bilateral task yielded right visual field superiority in 98% of the subjects and the magnitude of the superiority was over three times as large as in the unilateral task. Different sex × familial sinistrality × VHF interactions obtained on the tasks. Combining the advantages of reaction time and bilateral presentation methods may substantially increase the resolving power of lateralized tachistoscopic tasks.     

Cross-modal correlation of dichotic and tachistoscopic language laterality tasks: the importance of familial sinistrality

Previous studies have found little if any correlation between dichotic and tachistoscopic language laterality task performance asymmetries. Problems with these studies have been that quite dissimilar auditory and visual tasks have often been used, and the reliability of the asymmetry measures has generally been unknown or, when known, relatively poor. We assessed the cross-modal correlation for two tasks, the Bilateral Object Naming Latency Task (BONLT) and the Dichotic Object Naming Latency Task (DONLT). These tasks are highly similar and have demonstrated high reliabilities. A significant, though rather small, cross-modal correlation was found (r = +.28). When cross-modal correlations were computed for FS- and FS+ subjects separately, no correlation was found for FS+ subjects (r = +.02), but the correlation for FS- subjects was highly significant (r = +.54, p less than .004). This led us to reexamine some previously collected data (P.L. Van Eys and W. F. McKeever, 1988, Brain and Cognition, 4, 413-429) which had administered two highly reliable language laterality tasks (the BONLT and the Dichotic Consonant Vowel Task), but had not assessed cross-modal correlation. A significant cross-modal correlation was found for FS- but not for FS+ subjects. The results are consistent with the hypothesis of H. Hecaen, M. De Agnostini, and A. Monzon-Montes (1981, Brain and Language, 12, 261-284) which suggests that one effect of FS+ is to induce a greater heterogeneity of localizations of different language processes.     

Visual field differences in verbal tasks: Effects of task familiarity and sex of subject

Four experiments using normal subjects investigated differences in magnitude of the right visual field (RVF) superiority as a function of word material (frequency and concreteness/imageability status), nonword letter strings (some of which were homophonic with nonpresented real words), and type of task (overt naming or lexical decision with discriminatory manual responses) as well as sex of the subject and the subject's familiarity with the material. Both latency and error measures showed that RVF superiority was more consistent when overt naming was required and with male subjects. For female subjects engaged in lexical decisions, a left visual field (LVF) superiority was often apparent, especially in the first half of an experimental sequence; when actually naming the items aloud, they showed field asymmetries similar to males. Except from an analysis of errors, there was little evidence to support differential right hemisphere mediation of high frequency concrete/imageable materials. It is suggested that in females, right hemisphere space normally reserved for visuospatial processing may have been invaded by secondary speech mechanisms. These mechanisms appear to operate at an essentially lexical level and may act in a supportive or auxiliary capacity for difficult or unfamiliar material; they seem to be equally concerned with both phonological and graphological processing and may account for the well-known female superiority in verbal tasks and inferiority in visuospatial tasks. Other findings are discussed such as the degree of consistency of the field differences, both for the same subjects and for the same stimulus materials under different task requirements and experimental conditions.     

Attributions for Performance on Luck and Skill Tasks: Effects of Outcome,Sex of Performer,and Sex of Subject

Attributions for and evaluations of a stimulus persons's preformance were assessed as a function of the sex of the stimulus person, sex of the observer, type of task (luck or skill), and outcomes (success or failure). An interaction between type of task and sex of stimulus person was expected, with observers expecting males to perform better than females on the skill task because of ability, and females to perform better than males on the luck task because of task ease. The results provided partial support for the predicted interaction. Task difficulty was more relevant for females on the luck task than for males. Effort was rated as more important for females than for males when the success was on the skill task. All of the ratings were influenced by the task-type manipulation.     

Problem solving as a function of extraversion and masculinity

The present study aimed at investigating the differences in performance on five problem solving tasks in terms of extraversion-introversion and masculinity-femininity of 48 University males and females assigned to meet the requirements of a 2 × 2 × 2 between group factorial design. While the first four problems were solved with a time limit, and then the scores combined to obtain a composite index, in the fifth, the index of performance was both number of trials and time taken to solve the problem. The data were analyzed by ANOVA. The findings are: (i) Introverts are superior to extraverts on the composite performance index of the first four problems. (ii) On the fifth problem (i.e. problem squares) the male subjects performed significantly better than their female counterparts. (iii) A highly significant personality × sex role × sex interaction revealed that in males extraversion determines the level of performance, i.e. introverts perform better than extraverts regardless of their scores on masculinity-femininity; and in females masculinity boosts the performance of the extraverted group, and femininity hinders the performance of this group. (iv) When males and females were matched on E-I and M-F, the expected sex differences failed to emerge.     

Sex guilt,sexual arousal,and urinary acid phosphatase output

This study investigated the relationship between the personality variable sex guilt and a proposed physiological measure of sexual arousal (urinary acid phosphatase level). Urinary acid phosphatase levels of 43 male college students were assessed both basally and after exposure to 19 sexually themed slides. As predicted, sex guilt was inversely related to both basal acid phosphatase level and changes in acid phosphatase level upon exposure to the erotic stimuli. In addition, sex guilt scores were correlated with subjects' self-reported reactions to the erotic stimuli. The relationships obtained provided further construct validity evidence for the sex-guilt measure. Finally, the relationship between sexual arousal and urinary acid phosphatase level was explored. The data provided only partial validation for the proposed relationship between sexual arousal and urinary acid phosphatase output.     

Effects of fear of success, fear of failure, type of opponent, and feedback on female achievement performance

Female undergraduates (N = 240) assessed for fear of success (FS) and fear of failure (FF) competed against a male, female, or no opponent (norms) on an alpha-numeric substitution task. After completing one set of trials, subjects arbitrarily received success or failure feedback, then performed again. While there were no significant effects when subject's FS classification was based on total scores from the entire set of four cues used, performance effects were found for Horner's original cue: FS-absent females performed better against a male than a female opponent, whereas the reverse was true for the FS-present subjects. Two of the other FS cues interacted with FF: at low levels of FF, FS-absent subjects performed better than FS-present subjects; for high levels of FF, there were no differences between FS groups. A number of postperformance affect ratings were consistent with theoretical expectations that FS-present females would experience more negative effect over success in achievement contexts than would FS-absent females.     

Word matching and Lexical Decisions: A Visual Half-Field study

In unilateral Visual Half-Field tasks visuospatial and linguistic processing were compared. In a Word Matching task subjects judged the physical identity of simultaneously presented pairs of three-letter words or legal nonwords. No mainfield effects were found, but word pairs were recognized better and faster as "same" than nonword pairs. Latencies and errors in "different" pairs increased monotonically with position of letter change in the left but not in the right visual field (RVF), suggesting a serial, letter-by-letter way of processing for the right hemisphere and a whole word approach for the left. At this perceptual level the ability to store lexical information from the icon is stressed as a hemisphere-specific factor. In a Lexical Decision task the same subjects judged the same items on the word/nonword dimension. A RVF advantage associated with words as compared to nonwords occurred, as expected. Additional analysis suggests that order and difficulty of tasks may influence females' laterality, as compared to that of males.     

Defensiveness, intimacy, and heterosexual attraction

A previous study by Dion and Dion (1975) revealed that highly defensive individuals were less likely to report having experienced romantic love than less defensive persons. The hypothesis that this finding might reflect differential reactions to interpersonal intimacy was directly examined in the present study using a self-disclosure paradigm. To assess subjects' defensiveness, undergraduate women first completed the Marlowe-Crowne Social Desirability Scale. In a second session, subjects were exposed to high and low disclosing targets of the same and opposite sex and chose discussion topics for each target. On intimacy of self-disclosure, a “reciprocity effect” occurred: subjects chose more intimate topics for high vs low-disclosing targets. However, highly defensive women gave a less favorable self-presentation to male vs female targets. They also expressed less liking for high compared to low intimate targets and males vs females than less defensive subjects. The implications of these results for heterosexual attraction were discussed.     

The nature of the task-stimulus interaction in the tachistoscopic recognition of kana and kanji words

To investigate the nature of the task-stimulus interaction in tachistoscopic recognition of kana and kanji, right-handed normal subjects performed two phonological tasks and two visual tasks. In the phonological tasks, the subjects compared the members of a pair of kana or kanji appearing in the right or left visual field on the basis of phonological identity; while in the visual tasks, they compared the members of a pair of kana or kanji on the basis of visual identity. The results showed a significant Visual Field × Task interaction as well as a significant Task × Stimulus interaction, indicating that both the type of stimuli and the nature of task demands contribute importantly to the determination of visual field asymmetry and hence the relative participation of each hemisphere.     

Words, hemispheres, and dissociable subsystems: the effects of exposure duration, case alternation, priming, and continuity of form on word recognition in the left and right visual fields

Three experiments explore aspects of the dissociable neural subsystems theory of hemispheric specialisation proposed by Marsolek and colleagues, and in particular a study by [Deason, R. G., & Marsolek, C. J. (2005). A critical boundary to the left-hemisphere advantage in word processing. Brain and Language, 92, 251–261]. Experiment 1A showed that shorter exposure durations for lower-case words (13 ms) are associated with reduced right visual field (RVF) advantages compared with longer exposure durations (144 ms). Experiment 1B compared report accuracy for lower case and mixed case words at the same exposure duration (144 ms). The RVF advantage was reduced for mixed case words due to case alternation having more of an adverse effect in the RVF than in the LVF. Experiment 2 tested a different prediction of dissociable neural subsystems theory. Four-letter words were presented in mixed case in the LVF or RVF for 100 ms. They were preceded at the same location by a prime which could be in the same word in the same alternation pattern (e.g., FlAg–FlAg), the same word in the opposite alternation pattern (e.g., fLaG–FlAg), or an unrelated letter string in the same or opposite case alternation pattern (WoPk–FlAg or wOpK–FlAg). Relative to performance in the letter string prime conditions, which did not differ significantly between the two visual fields, there was more of an effect of word primes in the RVF than in the LVF. Importantly, the benefit of a word prime was the same whether the prime was in the same alternation pattern or was in the opposition alternation pattern. We argue that these results run contrary to the predictions of dissociable neural subsystems theory and are more compatible with theories which propose that a left hemisphere word recognition system is responsible for identifying written words, whether they are presented in the LVF or the RVF, and that letters are processed to an abstract graphemic level of representation before being identified by that system.     

Handedness and sex differences in hemispheric asymmetry

A study was designed to assess the contributions of the factors of sex and familial history to cerebral dominance, where cerebral dominance was inferred from laterality on a dichotic listening task. The 144 subjects were selected from a larger sample on the basis of handedness, sex, and familial history of sinistrality, and tested on a task involving the dichotic presentation of CV syllables. Analysis of the data indicated that in female subjects, the presence of familial sinistrality increased the likelihood that they present atypical left-ear superiorities, while in males the converse was the case. Moreover, there was a significant sex difference overall, such that males were more clearly lateralized than females. A review of other dichotic listening studies provided support for the reliability of this sex difference for dichotic tasks using verbal material. A review of the clinical literature indicated that the hypothesis of a sex difference is at least tenable and merits further investigation. However, the possibility that there is a sex difference in the cognitive strategy used in dichotic listening cannot be ruled out.     

Hemispheric asymmetries and cognitive flexibility: an ERP and sLORETA study

Although functional cerebral asymmetries (FCAs) affect all cognitive domains, their modulation of the efficacy of specific executive functions is largely unexplored. In the present study, we used a lateralized version of the task switching paradigm to investigate the relevance of hemispheric asymmetries for cognitive control processes. Words were tachistoscopically presented in the left (LVF) and right visual half field (RVF). Participants had to categorise the words either based on their initial letters, or according to their word type. On half of the trials the task changed (switch trials) whereas on the other half it stayed the same (repeat trials). ERPs were recorded and the neural sources of the ERPs were reconstructed using standardised low resolution brain electromagnetic tomography (sLORETA). In the word type task, participants were faster on repeat trials when stimuli were presented in the RVF. In contrast, in the initial letter task participants were faster on repeat trials and in general more accurate after stimulus presentation in the LVF. In both tasks, no hemispheric asymmetries in reaction times were observed on switch trials. On the electrophysiological level, we observed a left lateralization of the N1 that was mediated by activation in the left extrastriate cortex as well as a greater positivity of the P3b after stimulus presentation in the RVF compared to the LVF that was mediated by activation in the superior parietal cortex. These results show that FCAs affect the neurophysiological correlates of executive functions related to task switching. The relation of neurophysiological and behavioural asymmetries is mediated by task complexity, with more complex tasks leading to more interhemispheric interaction and smaller left-right differences in behavioural measures. These findings reveal that FCAs are an important modulator of executive functions related to cognitive flexibility.     

Studies toward a model of laterality effects for picture and word naming

Experiments requiring the naming of bilaterally presented nouns, picturable nouns, consonant-vowel-consonant (CVC) nonwords, and line drawings are reported. In order to eliminate order of report strategies and facilitate comparison across experiments, the stimulus to be reported first was cued by underlining at presentation of each trial. Large right visual hemifield (RVF) superiorities were found to arise from both first and second reports for naming nouns and CVC nonwords. Drawings and picturable nouns, however, produced only a small RVF superiority arising entirely from subjects' second reports. It is proposed that hemispheric laterality effects for naming visually presented stimuli can arise from three principal sources, and the application of this model to existing studies is outlined.     

Skill-set,success outcome,and mania as determinants of the illusion of control

The illusion of control, the tendency for individuals to approach chance tasks with skill-appropriate strategies, was studied. Subjects premeasured on a mania scale were classified as either high (HM) or low (LM) in mania. In the first phase of the study, HM and LM subjects performed 30 trials on either a skill (verbal associates) or chance (coin-toss) task and were given either 20, 50, or 80% success feedback. After Task 1 was completed, subjects filled out an attribution questionnaire. In the final phase of the study, subjects anticipated 30 more trials either on a skill or chance task. Subjects' predicted successes were measured. It was hypothesized that predicted successes on anticipated skill and chance tasks would be affected more by outcomes on a previous skill task than by outcomes on a previous chance task. The results for the anticipated skill task directly supported the hypothesis. On the anticipated chance task, the hypothesis was confirmed for HM subjects only. The results are discussed in terms of how previous skill experiences may induce a set to control ungovernable situations for individuals with manic reactions.     

Human peak shift: Analysis of the effects of three-stimulus discrimination training

In a series of studies, the effects of different types of intradimensional discrimination training on human auditory frequency generalization were examined. When subjects were trained with a single S− located on one or the other side of S+, postdiscrimination gradients were displaced away from S−. Subjects trained with two negative stimuli both on one side of S+ showed a greater extent of displacement with true peak shift. In a second experiment the procedures were repeated with two fixed amounts of training: either 12 or 42 training trials. Again the subjects trained with two negative stimuli showed more shift than those trained with one S−, and this effect was independent of amount of training. Experiment 3 showed increased peak shift when two positive stimuli surrounded a central S− as compared to groups with a single S+ and S−. The general conclusion is that training with more difficult, three-stimulus discrimination problems results in enhanced peak shift.