Handedness differences in information framing

Previous research has shown that strength of handedness predicts differences in sensory illusions, Stroop interference, episodic memory, and beliefs about body image. Recent evidence also suggests handedness differences in the susceptibility to common decision biases such as anchoring and sunk cost. The present paper extends this line of work to attribute framing effects. Sixty-three undergraduates were asked to advise a friend concerning the use of a safe allergy medication during pregnancy. A third of the participants received negatively-framed information concerning the fetal risk of the drug (1–3% chance of having a malformed child); another third received positively-framed information (97–99% chance of having a normal child); and the final third received no counseling information and served as the control. Results indicated that, as predicted, inconsistent (mixed)-handers were more responsive than consistent (strong)-handers to information changes and readily update their beliefs. Although not significant, the data also suggested that only inconsistent handers were affected by information framing. Theoretical implications as well as ongoing work in holistic versus analytic processing, contextual sensitivity, and brain asymmetry will be discussed.     

Handedness patterns in deaf persons

The handedness patterns of 226 deaf high-school and college students were compared to those of 210 college students with normal hearing. Both groups evidenced many more right-handed than left-handed members, as determined by responses to a hand preference questionnaire and performance on an activity test battery. There was, however, a significantly higher incidence of left-handedness among the deaf subjects than among the hearing. Moreover, the left-handed deaf students were found to be less likely to have deaf relatives, and to have been introduced to sign language later in their development than the deaf student population as a whole. These findings were interpreted as showing that age of acquisition of language was related to the development of handedness patterns, whereas auditory processing experience probably was not.     

Handedness and dementia

Some researchers have speculated that left-hand dominance is more prevalent among patients suffering from dementia of the Alzheimer's type which began prior to age 65 yr. and that, in those patients, the disease runs a more rapid course. In the present study, seven left-handed dementia patients were matched with seven right-handed dementia patients on the basis of age and years of education and were compared with regard to neuropsychological compromise. While the left-handed group was somewhat more impaired than the right-handed subjects, the difference between the two groups was not statistically significant.     

Handedness and immune function

Geschwind, Galaburda, and Behan (GBG) have suggested that in utero levels of testosterone influence both cerebral and immune system developments (Geschwind and Behan, 1982; Geschwind and Galaburda, 1984; Geschwind and Galaburda, 1985). According to this theory, high levels of testosterone result in greater incidences of left-handedness, deviations from standard distribution of cerebral functions (known as anomalous dominance), and increased autoimmune dysfunction. While the original data supported these assertions, more recent tests of the hypothesis have been equivocal. One criticism of these studies is that the definition of both handedness and anomalous dominance are too vague. It was one of the aims of this project to investigate and clarify the GBG model by examining four different aspects of handedness as well as a more direct measure of anomalous dominance. In order to extend the GBG model, degree of left-handedness, general immune system functioning, and current testosterone levels were also examined. First, it was predicted and found that left handers had a higher incidence of autoimmune diseases in their immediate families than did right handers. Second, those left handers with an incidence of at least one autoimmune disease were more strongly left-handed than were those with no incidence of autoimmunity. Finally, it was observed that higher testos terone levels were supportive of general immunity. The present findings both support and expand the GBG model.     

Handedness and cognitive bias

2165 Subjects, ranging from nine-year-old schoolchildren to adult students, took Test AH 2/3 which yields subscores on Verbal, Numerical and Perceptual reasoning. The left-handers are compared with the right-handers, differences being found with respect to cognitive bias, sex, age and nationality.     

Handedness and calendar orientations in time-space synaesthesia

In one common variant of time-space synaesthesia, individuals report the consistent experience of months bound to a spatial arrangement, commonly described as a circle extending outside of the body. Whereas the layout of these calendars has previously been thought to be relatively random and to differ greatly between synaesthetes, Study 1 provides the first evidence suggesting one critical aspect of these calendars is mediated by handedness: clockwise versus counter-clockwise orientation. A study of 34 time-space synaesthetes revealed a strong association between handedness and the orientation of circular calendars. That is, left-handed time-space synaesthetes tended to report counter-clockwise arrangements and right-handed synaesthetes clockwise. Study 2 tested whether a similar bias was present in non-synaesthetes whose task was to memorize and recall the spatial configuration of a clockwise and counter-clockwise calendar. Non-synaesthetes' relative performance on these two sorts of calendars was significantly correlated with their handedness scores in a pattern similar to synaesthetes. Specifically, left-handed controls performed better on counter-clockwise calendars compared to clockwise, and right-handed controls on clockwise over counter-clockwise. We suggest that the implicit biases seen in controls are mediated by similar mechanisms as in synaesthesia, highlighting the graded nature of synaesthetic associations.     

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.     

Handedness of handedness researchers.

This study tested the hypothesis that laterality and handedness researchers are more likely than other researchers to be left-handed. A questionnaire assessing hand preference was sent to authors of articles which either dealt with handedness (N = 50) or other aspects of laterality (N = 100) or did not concern laterality (N = 50). The proportion of left-handers was highest in the handedness group (12.9%) and lowest in the non-laterality group (5.0%), but this difference did not reach significance.     

Handedness shapes children's abstract concepts

Can children’s handedness influence how they represent abstract concepts like kindness and intelligence? Here we show that from an early age, right‐handers associate rightward space more strongly with positive ideas and leftward space with negative ideas, but the opposite is true for left‐handers. In one experiment, children indicated where on a diagram a preferred toy and a dispreferred toy should go. Right‐handers tended to assign the preferred toy to a box on the right and the dispreferred toy to a box on the left. Left‐handers showed the opposite pattern. In a second experiment, children judged which of two cartoon animals looked smarter (or dumber) or nicer (or meaner). Right‐handers attributed more positive qualities to animals on the right, but left‐handers to animals on the left. These contrasting associations between space and valence cannot be explained by exposure to language or cultural conventions, which consistently link right with good. Rather, right‐ and left‐handers implicitly associated positive valence more strongly with the side of space on which they can act more fluently with their dominant hands. Results support the body‐specificity hypothesis ( Casasanto, 2009 ), showing that children with different kinds of bodies think differently in corresponding ways.     

Handedness and footedness in Korean college students

This study was conducted to obtain normative data on foot preference and to compare footedness and handedness in a large sample (N = 866) of college students in Korea, where left-hand use for writing and other public acts is severely restricted (Kang & Harris, 1993). Based on scores from Korean-language versions of the Edinburgh Handedness Inventory (EHI; Oldfield, 1971) and the Waterloo Footedness Questionnaire Revised (WFQ-R; Elias, Bryden, & Bulman-Fleming, 1988), 11% of the subjects were left-footed but only 4.2% as left-handed. A significantly higher percentage of left-handers than right-handers showed crossed lateral preference, that is, for preference of the opposite-side foot. Of the left-handers with crossed preference, the majority were inconsistent left-handers (ILH; Peters & Servos, 1989), whereas most of those with uncrossed preference were consistent left-handers (CLH). Factor analysis of the EHI and WFQ-R revealed 2 handedness factors and 2 footedness factors. The footedness factors for skilled unipedal actions and for balancing-stabilizing varied in direction, strength, and relation to handedness in mixed-footers and left-handers, consistent with the possibility that the division of footedness into these categories might be neuropsychologically meaningful.     

Handedness and locus of control

Groups of 15 left-, 15 mixed-, and 39 right-handers were tested with Rotter's Locus of Control Scale. Contrary to prediction, it was found that both left- and right-handers scored significantly higher, i.e., were more externally controlled, than mixed-handers. Primarily these data suggest a complex relationship between handedness and personality and they serve to reinforce the need to include mixed-handers in research on handedness.     

Handedness in Musicians: Bimanual Constraints on Performance

Handedness in musicians was examined in terms of the relative roles of the hands in bimanual motor activity involved in instrumental performance. Musicians playing instruments requiring temporally integrated (e.g., strings and woodwinds), as opposed to independent (e.g., keyboard instruments), bimanual motor activity were found to exhibit weaker degrees of handedness. There were no significant differences between groups in direction of handedness. Results are interpreted in terms of greater bilateral hemispheric integration and control of fine motor movements among subjects exhibiting mixed-handedness.