Gina M. Grimshaw

The Flinders Handedness survey (FLANDERS): A brief measure of skilled hand preference

Knowing whether an individual prefers the left or right hand for skilled activities is important to researchers in experimental psychology and neuroscience. The current study reports on a new measure of skilled hand preference derived from the Provins and Cunliffe (1972) handedness inventory. Undergraduates (n = 3324) indicated their lateral preference for their hands, feet, eyes and ears. A measure of hand performance and familial handedness was also obtained. Factor analysis identified ten items that loaded on skilled hand preference and these were included in the new FLANDERS questionnaire. Cluster analysis of the new questionnaire revealed three distinct groups (left-, mixed- & right-handed). The new test showed a strong association with other measures of lateral preference and hand performance. Scores on the test were also related to the sex of the respondent and the hand preference of their parents. The FLANDERS provides a measure of skilled hand preference that is easy to administer and understand and should be useful for experimenters wanting to screen for hand preference.

An asymmetric inhibition model of hemispheric differences in emotional processing

Two relatively independent lines of research have addressed the role of the prefrontal cortex in emotional processing. The first examines hemispheric asymmetries in frontal function; the second focuses on prefrontal interactions between cognition and emotion. We briefly review each perspective and highlight inconsistencies between them. We go on to describe an alternative model that integrates approaches by focusing on hemispheric asymmetry in inhibitory executive control processes. The asymmetric inhibition model proposes that right-lateralized executive control inhibits processing of positive or approach-related distractors, and left-lateralized control inhibits negative or withdrawal-related distractors. These complementary processes allow us to maintain and achieve current goals in the face of emotional distraction. We conclude with a research agenda that uses the model to generate novel experiments that will advance our understanding of both hemispheric asymmetries and cognition-emotion interactions.

Eye Tracking of Men’s Preferences for Female Breast Size and Areola Pigmentation

Sexual selection via male mate choice has often been implicated in the evolution of permanently enlarged breasts in women. While questionnaire studies have shown that men find female breasts visually attractive, there is very little information about how they make such visual judgments. In this study, we used eye-tracking technology to test two hypotheses: (1) that larger breasts should receive the greatest number of visual fixations and longest dwell times, as well as being rated as most attractive; (2) that lightly pigmented areolae, indicative of youth and nubility, should receive most visual attention and be rated as most attractive. Results showed that men rated images with medium-sized or large breasts as significantly more attractive than small breasts. Images with dark and medium areolar pigmentation were rated as more attractive than images with light areolae. However, variations in breast size had no significant effect on eye-tracking measures (initial visual fixations, number of fixations, and dwell times). The majority of initial fixations during eye-tracking tests were on the areolae. However, areolar pigmentation did not affect measures of visual attention. While these results demonstrate that cues indicative of female sexual maturity (large breasts and dark areolae) are more attractive to men, patterns of eye movements did not differ based on breast size or areolar pigmentation. We conclude that areolar pigmentation, as well as breast size, plays a significant role in men’s judgments of female attractiveness. However, fine-grained measures of men’s visual attention to these morphological traits do not correlate, in a simplistic way, with their attractiveness judgments.

The relationship between hand preference, hand performance, and general cognitive ability

The idea that handedness indicates something about a persons cognitive ability and personality is a perennial issue. A variety of models have been put forward to explain this relationship and predict a range of outcomes from higher levels of cognitive ability in left-handers or moderate right-handers to lower levels of achievement in left- or mixed-handers. We tested these models using a sample (n = 895) drawn from the BRAINnet database (www.brainnet.net). Participants completed a general cognitive ability (GCA) scale and a test of hand preference/performance. Moderate right-handers, as indexed by their performance measures, had higher GCA scores compared with strong left- or right-handers. The performance measure also showed lower levels of GCA for left-handers compared with right-handers. The hand preference data showed little or no association with cognitive ability-perhaps because this measure clusters individuals toward the extremes of the handedness distribution. While adding support to Annetts heterozygous advantage model, which predicts a cognitive disadvantage for strong left- or right-handers, the data also confirm recent research showing a GCA disadvantage for left-handers. Although this study demonstrates that handedness is related to cognitive ability, the effects are subtle and might only be identified in large-scale studies with sensitive measures of hand performance.

Going beyond students: An association between mixed-hand preference and schizotypy subscales in a general population

Research on the sub-clinical condition of schizotypy suggests that it is associated with mixed handedness. To date, however, this research has focussed on undergraduate populations. If the association between schizotypy and mixed-handedness is the result of an underlying neurological trait, it is important to demonstrate that the effect extends to the general population. With this in mind, 699 participants were drawn from a wide community sample. Schizotypy was measured using the Psychosis Proneness Questionnaire and handedness was assessed using the Annett inventory. To avoid the sometimes arbitrary definitions of left-, right- and mixed-handed, regression analyses were used to explore the data. There was no evidence of a difference in schizotypy between individuals with a left- or right-hand preference. People with a mixed-hand preference, however, had higher scores on PER-MAG (Perceptual Aberration and Magical Ideation) and HYP-IMP (Hypomania and Impulsive Non-Conformity) scales (positive traits). No effect was observed for the SAN (Social Anhedonia) and PAN (Physical Anhedonia) scales (negative traits). The nature of the association between schizotypy and handedness observed in the current study is similar to that reported for student populations. The possibility that the association is related to response biases or a biological mechanism is discussed.

Controlling for stimulus dominance in dichotic listening tests: A modification of !l.

Dichotic listening procedures have been used to assess cerebral lateralization in normal subjects. One particularly useful technique is the use of stimuli that fuse into a single percept. Although this procedure has many advantages over other dichotic listening methods, it is particularly susceptible to stimulus dominance, which acts as noise in a subjects response data, thus reducing the power of any statistical test of the ear advantage. It is proposed that the solution to this problem is a log-linear analysis of the response data to yield a A-type index (A*) that is a measure of ear dominance independent of stimulus dominance. Details of the analysis are provided, as well as a sample analysis of data collected from 104 right-handed and 30 left-handed subjects. Comparisons are drawn between the log-linear analysis and other methods that have been proposed to control for stimulus dominance in this single-response dichotic fusion procedure.

The role of intellectual openness in the relationship between hand preference and positive schizotypy

Recently it has been suggested that the relationship between positive schizotypy and mixed handedness is limited to questionnaire measures, and thus reflects some aspect of questionnaire-taking behaviour as opposed to some aspect of atypical brain organisation. The current study set out to explore this possibility. Undergraduate psychology students completed the Magical Ideation Scale, the Waterloo Handedness Questionnaire-Revised, a manual dot-filling task, and an inventory measuring the personality trait of intellectual openness. On the questionnaire measure, magical ideation was related to mixed handedness on unskilled but not skilled hand preference; however, this relationship was partially mediated by intellectual openness. Magical ideation was not related to the behavioural measure of handedness. These findings suggest that responses on handedness questionnaires partially reflect personality variables, and such effects should be considered in future research on the nature of the relationship between handedness and schizotypy.

Once more with feeling: The effects of emotional prosody on hemispheric specialisation for linguistic processing

Abstract Speech perception requires a bilateral network of neural systems, with the left hemisphere specialised for linguistic processes including phonology, and the right hemisphere specialised for paralinguistic processes including emotional prosody. The present study used dichotic listening to determine how these two processing systems interact. Experiment 1 confirmed that the left hemisphere was specialised for the linguistic task, and the right hemisphere was specialised for the prosodic task. In Experiment 2, participants performed the linguistic task, but the words were spoken in prosodies that were neutral, happy, angry, or sad. Although the emotional prosody was irrelevant for the task, there was an attenuation of the typical right ear advantage when words were spoken with sad prosody, suggesting greater right hemisphere contributions to linguistic processing for sad speech. Similar effects were not observed with angry or happy prosody, suggesting that emotional prosody per se does not facilitate right hemisphere linguistic processing. Results are interpreted in terms of both psychoacoustic and emotion-specific theories of hemispheric specialisation.

Magical ideation is related to questionnaire but not behavioural measures of handedness

Magical ideation has repeatedly been shown to be related to handedness, with mixed-handers exhibiting higher levels of magical thinking. However, most previous research has assessed hand preference with a questionnaire measure, leaving open the possibility that the correlation reflects some aspect of questionnaire-taking behaviour and not an underlying neuropsychological relationship. The present study addressed this issue by administering the Magical Ideation Scale (Eckblad & Chapman, 1983), the Waterloo Handedness Questionnaire-Revised (Elias, Bryden, & Bulman-Fleming, 1998), and a manual dot-filling task (Tapley & Bryden, 1985) as a behavioural measure of handedness to an undergraduate student sample. The expected relationship between magical ideation and handedness as assessed by the questionnaire was observed. However, magical ideation was not related to the behavioural measure of handedness. Results cast doubt on a neuropsychological interpretation of the relationship between handedness and magical ideation in sub-clinical populations.

A sinister plot? Facts, beliefs, and stereotypes about the left-handed personality

Is there a left-handed personality? Is there a left-handed stereotype? Although psychologists have enthusiastically compared left- and right-handers across myriad cognitive, behavioural, and neuropsychological domains, there has been very little empirical investigation of the relationship between handedness and personality. In Study 1 we assessed the Big 5 personality traits (extraversion, agreeableness, conscientiousness, emotionality, and openness to experience) in a sample of 662 young adults in New Zealand. Left- and right-handers did not differ on any factor. However, there was a curvilinear relationship between hand preference and extraversion; mixed-handers were more introverted than either left- or right-handers. This finding is consistent with other research indicating that degree may be of more psychological consequence than direction of handedness. In Study 2 we assessed beliefs and stereotypes about the left-handed personality. Both left- and right-handers shared the belief that left-handers are more introverted and open to experience than right-handers. This stereotype is not negative, and argues against the status of left-handers as a stigmatised group in modern Western culture.