Handedness, sex, and eyedness as moderating variables in the relation between hypnotic susceptibility and functional brain asymmetry.

The number of eye movements to the right in response to verbal and spatial questions in an E-facing-S situation correlated moderately with measured hypnotic responsiveness for a sample of 30 male and 30 female right-handed undergraduates. This finding confirms earlier indications that hypnotic responsiveness may be a right hemisphere function in right-handed Ss. The correlation was not significant for 19 male and 11 female left-handed Ss. Further breakdowns of the sample produced much higher correlations with hypnotizability, indicating the roles of sex, handedness, and eyedness as moderating variables. Right-handed males yielded a correlation of -.68 and left-handed females a correlation of .58, while the correlations for right-handed females and left-handed males were nonsignificant. Left-handed males, if also left-eyed, showed a correlation of .52. Left-handed males who were right-eyed, however, showed a correlation of -.41. Right-handed females who were left-eyed and right-eyed produced correlations with appropriate opposite signs, but the differences were not significant. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recall strategies in three-channel immediate memory.

Digits were spoken through earphones via 3 simultaneous auditory "channels," created by having 1 digit spoken to the left ear only, another to the right ear only, and a third (middle channel) to both ears at once. Also, each channel was spoken by a different voice, a woman's in the middle, and different men's voices to left and right. 18 right-handed and 18 left-handed Ss heard a series of 2 such triplets, with onsets of 1 sec. apart. Ss instructed to report the digits channel by channel recalled as many digits as those instructed to report them triplet by triplet, but Ss who were permitted free recall chose the triplet-by-triplet strategy more often than the channel-by-channel one. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The grammar of action and reversal errors in children's printing.

36 left-handed and 36 right-handed kindergarten children were asked to print after seeing a series of reversible letters and numbers presented individually on slides or flash cards. Regardless of handedness, both groups of Ss found the left–right orientation cues of the same letters and numbers difficult to recall. This challenges a proposal expressed in the "grammar of action" that claims that certain reversal errors in children's printing result from the inappropriate application of the horizontal motor rule, because although left- and right-handed children use this rule, they do so in different ways and therefore should have produced different errors. Another sample of 86 right-handed children from nursery school through Grade 1 was given the same printing task. Findings from this 2nd sample provide an additional challenge to the grammar of action by showing that reversals of the letter N, which are also thought to result from a misapplication of motor rules, decrease in frequency along with reversals of other letters and numbers, instead of increasing as predicted, during the developmental period when the motor rules that are said to be responsible for reversals of this particular letter become more strongly established. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Paradoxical bilateral asymmetry in bone size and bone mass in the hand

Among 227 chronic renal disease patients, micrometer caliper radiogrammetric measurements of the second metacarpal at midshaft showed the right metacarpal to be larger (with greater bone area) and with a greater cortical area than the left second metacarpal, both in 208 right-handed individuals and in 19 left-handed individuals. This direction of asymmetry was individually characteristic of the majority of individuals, whether right-handed, left-handed or ambidextrous.     

Interhemispheric cooperation: Left is left and right is right, but sometimes the twain shall meet.

Interhemispheric cooperation in the processing of nonsense syllables projected simultaneously to both hemispheres was investigated in 2 experiments. Stimuli were projected unilaterally in the left and right visual fields (LVF, RVF) and bilaterally (the same syllable in both fields, BVF; Exp 1, 64 right-handed Ss) or centrally (CVF; Exp 2, 32 right-handed Ss). Accuracy and error patterns differed for the LVF and RVF. Error patterns were intermediate for the BVF–CVF and were partly shifted toward the RVF for Ss with large RVF advantages and toward the LVF for those with small asymmetries. Regression analyses showed that variance in BVF–CVF error patterns was jointly predicted by LVF and RVF variances. Both hemispheres, as demonstrated by means and regression analyses, contribute to the processing of bihemispherically presented syllables. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Handedness in first-episode psychotic patients and their first-degree biological relatives.

We evaluated the handedness of 58 schizophrenia patients and 54 of their relatives, 23 patients with major depression with psychosis and 24 of their relatives, 36 patients with bipolar psychosis and 33 of their relatives, and 119 nonpsychiatric Ss and 42 of their relatives. Computerized tomography measures were also available for a subset of the psychotic patients. The schizophrenia patients were significantly more left-handed than any of the other groups, and increased sinistrality was also associated with larger lateral ventricle to brain area ratios. The relatives of the schizophrenia patients did not significantly differ on handedness from either the relatives of the affective psychosis patients or the nonpsychiatric Ss. Findings do not support the notion that left-handedness in schizophrenia is genetically influenced. More research with larger family member data sets is warranted to further explore this possibility. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Functional magnetic resonance imaging of motor cortex: hemispheric asymmetry and handedness

A hemispheric asymmetry in the functional activation of the human motor cortex during contralateral (C) and ipsilateral (I) finger movements, especially in right-handed subjects, was documented with nuclear magnetic resonance imaging at high field strength (4 tesla). Whereas the right motor cortex was activated mostly during contralateral finger movements in both right-handed (C/I mean area of activation = 36.8) and left-handed (C/I = 29.9) subjects, the left motor cortex was activated substantially during ipsilateral movements in left-handed subjects (C/I = 5.4) and even more so in right-handed subjects (C/I = 1.3).     

Influence of concurrent auditory input on tactual processing in very young children: Developmental changes.

Investigated right-hemispheric specialization for tactual processing in 96 2–5 yr old right-handed children. Cross-modal transfer from touch to vision was assessed under conditions where Ss palpated shapes with either their left or right hand while music was simultaneously played to the left ear, right ear, or neither ear. This task pitted music against palpation such that both tasks involved the same or different cerebral hemispheres (if music and haptic perception are both lateralized in the right hemisphere as is thought). Results show that in the absence of music, Ss at each age showed a left-hand (right-hemisphere) advantage. The adultlike patterns of ipsilateral interference from music were evident among 4- and 5-yr-olds, in that music to the left ear selectively disrupted left-hand performance. The adultlike pattern was absent at ages 2 and 3 yrs, and music to the right ear disrupted left-hand performance at these ages. Music had an overall, nonselective interference on right-hand performance at all ages. The early appearing left-hand advantage and the lateralized nature of the interference observed among older Ss support the idea of a right-hemispheric specialization for tactual processing of form in young children. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pursuit gain and saccadic intrusions in first-degree relatives of probands with schizophrenia.

Oculomotor functioning of 26 probands (aged 18–45 yrs) with schizophrenia, 12 spectrum and 46 nonspectrum 1st-degree relatives (aged 16–72 yrs), and 38 nonpsychiatric control Ss (aged 19–67 yrs) was evaluated. Spectrum relatives had more anticipatory saccades (ASs) and lower pursuit gain than nonspectrum relatives, who had more ASs and lower pursuit gain than control Ss. Probands also had lower pursuit gain than nonspectrum relatives and control Ss but did not differ from other groups on AS frequency. Control Ss had more globally accurate pursuit tracking (root mean square [RMS] error deviation) than both relative groups, whereas probands had the poorest RMS scores. Square wave jerk frequency did not differentiate the groups. Attention enhancement affected the frequency of ASs but did not affect either the other intrusive saccadic event or RMS scores. These results offer evidence that eye-movement dysfunction may serve as a biological marker for schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thoughts beyond words: When language overshadows insight.

Four experiments examined whether verbalization can interfere with insight problem solving. In Exp 1, Ss were interrupted during problem solving and asked either to verbalize their strategies (retrospective verbalization) or engage in an unrelated activity (control). Ss in the retrospective verbalization condition were significantly less successful than control Ss at solving the problems. Exp 2 replicated the finding of Exp 1 and demonstrated that the control Ss' advantage was not due to any beneficial effect of the interruption. In Exp 3, concurrent, nondirective verbalization impaired the solving of insight problems but had no effect on noninsight problems. In Exp 4, the effect of concurrent verbalization on insight was maintained even when Ss were encouraged to consider alternative approaches. Together, these findings are consistent with the hypothesis that verbalization can result in the disruption of nonreportable processes that are critical to achieving insight solutions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Orientation of selective effects of body tilt on visually induced perception of self-motion

In this study, to test an inference from the 1991 Previc hypothesis that right-handers have a right-ear advantage, the durations of hearing for the right and left ears were compared for 81 right- and 45 left-handed high school students. In the present study, right-handedness was associated with a right-ear advantage and left-handedness was associated with a left-ear advantage. In addition, there was a significant positive correlation between the durations of hearing for the right and left ears and the scores for right-handedness for right-handed subjects. The durations of hearing for the right and left ears were negatively correlated with the left-handedness for left-handed subjects. These results suggest hand preference may be related to asymmetry of aural sensitivity.     

Tachistoscopic recognition of Kana and Hangul words, handedness and shift of laterality difference

Nonsense Kana words as verbal stimuli and Hangul words (Korean orthographic characters) as non-verbal were presented tachistoscopically in the left or right visual field to normal right-handed, non-familial left-handed Japanese subjects, who have not seen Hangul characters. Right-handers showed a significant right (or left) field superiority for the recognition of verbal (or non-verbal) stimuli. This pattern of differences found in right-handers is, though to a slightly lesser degree, also present in non-familial left-handers, while it is absent in familial left-handers. Initial left field superiority for Hangul word recognition shifted to no laterality difference in left-handers as well as in right-handers during the learning period for Hangul words.     

Differences in social and vocal behavior between left- and right-handed common marmosets (Callithrix jacchus).

Common marmosets (Callithrix jacchus) show either a left- or right-hand preference for reaching to pick up food and they retain the same preference throughout adult life. We compared the behavior of 10 right-handed and 10 left-handed marmosets, matched for age and sex. They were presented with live crickets both when alone and when in their social group. The marmosets captured more crickets and the latency to capture the first cricket was shorter when they were in a group than when they were alone. This effect of social facilitation was significantly greater for right- than left-handed individuals. The number of vocalizations (tsik, crackle, very brief whistle, cough, and phee) produced by the left- and right-handed marmosets differed significantly: right-handed marmosets produced an increased number of all of these calls when the crickets were presented, whereas left-handed marmosets did not show a change from pretesting levels. The right-handed marmosets also produced more tsik (mobbing) calls than left-handed marmosets when they were presented with a fear-inducing stimulus and performed more head cocking and parallax movements than the left-handed marmosets. Hence, hand preference is associated with differences in exploratory and social behavior, the latter including vocal communication. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Letters as spatial-oriented shapes and/or graphemic signs: a developmental study of left- and right-handed girls during the period of learning to read

This study is concerned with the problem of hemispheric specialization and/or cooperation in relation to development and manual laterality. The processing of alphabetic signs and its relationship to interhemispheric transfer and functional hemispheric asymmetries were studied by comparing left- and right-handed girls during acquisition of reading. The children perform matching tasks with letters having different orientations and with meaningless forms having the same orientations as the letters. Each subject performed the matching under three conditions: right/left intermanual transfer, left/right intermanual transfer, and dichaptic exploration. Results indicate: (1) A differentiated development between the two handednesses. (2) The functional lateralization change was different for left- and right-handed girls, a greater effect of the ability to identify the letter on matching tasks was observed for the right-handed children than for the left-handed children. These last results are discussed with regard to inter-hemispheric transfer and functional hemispheric asymmetry changes. We hypothesized a strategy difference between left- and right-handed girls and a difference in their ability to change their cognitive strategy (left-handers continue to favor a spatial coding with letters).     

Cerebral laterality in deaf and hearing children.

Studied the development of lateralization of cerebral function in 20 hearing and 20 prelingually deaf children using the concurrent task paradigm. Ss were aged 5–6 and 11–12 yrs; all were right-handed. Concurrent processing of a nonverbal task did not cause a selective hand impairment monitored by a manual tapping task. However, deaf Ss were more impaired than hearing Ss in both age groups. Using a concurrent verbal task, both groups manifested a selective impairment of right-hand performance. The deaf also showed a greater left-hand decrement than did the hearing Ss. This result suggests that hemispheric specialization may be less apparent in the deaf than in hearing children. The factor of cognitive task difficulty is suggested as an explanation of these results. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of handedness and type of movement on the contralateral preponderance of mu-rhythm desynchronisation

Event-related desynchronisation (ERD) of mu-rhythm was studied in 12 right-handed and 11 left-handed subjects during brisk and slow self-paced index finger movements of dominant and nondominant hand. Electroencephalogram (EEG) was recorded from the sensorimotor hand area of both hemispheres. The contralateral preponderance of mu-rhythm ERD in the pre-movement period showed the following changes: (i) the contrasts between left- and right-finger movements were larger and earlier in the dominant than nondominant hemisphere in both handedness groups; (ii) right-handed subjects showed larger lateralisation of mu-rhythm ERD prior to right-finger as compared to left-finger movements, whereas about equal contralateral preponderance for both sides was found in the left-handed; (iii) the lateralisation of mu-rhythm ERD was lower prior to brisk as compared to slow movements, especially in the left-handed subjects. The results demonstrate that hand dominance, handedness and type of movement influence the proportion of pre-movement mu-rhythm desynchronisation in the left and right peri-rolandic area.     

Hemispheric asymmetry in Down's Syndrome children.

Examined auditory processing of linguistic stimulation presented dichotically to groups of 30 Down's Syndrome (DS) children, 20 non-DS retarded children who were MA and CA matched, and 20 MA matched nonretarded children, all of whom were right-handed. Ss completed a knowledge-of-numbers test and the Slosson Intelligence Test. They then listened to 20 trials of a dichotic message at approximately 70–75 db and repeated digits they heard. DS Ss showed a significant left ear advantage in processing the auditory linguistic material, while the other Ss showed the normal right ear advantage. Findings corroborate that having DS has a specific effect on the functional organization of the CNS auditory system. The right hemisphere may not be as efficient as the left hemisphere at language processing. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cerebral lateralization for the processing of spatial coordinates and categories in left-and right-handers

Subjects judged whether a tachistoscopially lateralized drawing was identical or different to a drawing seen immediately before in free vision. The drawings depicted natural objects (e.g. animals). On half of the trials the tachistoscopic drawing presented the same objects but either the categorical or the coordinate spatial relations (according to Kosslyn's definitions [23]) between the objects were transformed. In the first experiment 38 right-handed subjects (half males and half females) were tested. Categorical judgements were faster when the match drawing appeared in the right visual field, whereas coordinate judgements were faster when the match drawing appeared in the left visual field. In the second experiment 26 right-handed and 40 left-handed subjects participated. Almost all the subjects were female. Right-handed subjects replicated the findings of the subjects in the first experiment. However, the LHs did not show any difference in response times between spatial conditions and visual fields. These findings support Kosslyn's hypothesis that the left and right hemispheres are specialized respectively for processing categorical and coordinate spatial relations. Moreover, they also suggest that this lateralization pattern is not typical of left-handers.     

Individual variation in hemispheric asymmetry: Multitask study of effects related to handedness and sex.

Functional hemispheric asymmetries were examined for right- or left-handed men and women. Tasks involved (1) auditory processing of verbal material, (2) processing of emotions shown on faces, (3) processing of visual categorical and coordinate spatial relations, and (4) visual processing of verbal material. Similar performance asymmetries were found for the right-handed and left-handed groups, but the average asymmetries tended to be smaller for the left-handed group. For the most part, measures of performance asymmetry obtained from the different tasks did not correlate with each other, suggesting that individual Ss cannot be simply characterized as strongly or weakly lateralized. However, ear differences obtained in Task 1 did correlate significantly with certain visual field differences obtained in Task 4, suggesting that both tasks are sensitive to hemispheric asymmetry in similar phonetic or language-related processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)