Nicole A. Thomas

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.

Upper and lower visual field differences in perceptual asymmetries

A leftward spatial bias has been observed with visuospatial attention tasks, including line bisection and the greyscales task. Upper and lower visual field differences have been observed on various tasks, with a lower visual field advantage occurring for motion, global processing and coordinate spatial judgments. Upper visual field advantages occur for visual search, local processing and categorical judgments. In perceptual asymmetries research, upper and lower visual field differences have not typically been scored separately, as most presentations have been central. Mixed results have made it difficult to determine whether lateral biases are stronger in the upper or the lower visual field. As length of presentation time differed in prior studies, this factor was examined to determine whether it would lead differential biases to emerge in each visual field. The greyscales task was used to investigate the interaction of visual field and presentation time within subjects (N=43). Eye tracking was used during the task and supported the hypothesis of a stronger left bias in the lower visual field. Presentation time and visual field interacted to influence performance. Prolonged presentation led to a stronger leftward bias in the lower visual field whereas the leftward bias was stronger in the upper visual field during brief presentation. Results showed a relation between the lower and left visual fields and the upper and right visual fields, which has not previously been shown in perceptual asymmetries. Further, it is suggested that functional differences between the visual streams could underlie the visual field differences in perceptual asymmetries.

The life of p: "just significant" results are on the rise.

Null hypothesis significance testing uses the seemingly arbitrary probability of .05 as a means of objectively determining whether a tested effect is reliable. Within recent psychological articles, research has found an overrepresentation of p values around this cut-off. The present study examined whether this overrepresentation is a product of recent pressure to publish or whether it has existed throughout psychological research. Articles published in 1965 and 2005 from two prominent psychology journals were examined. Like previous research, the frequency of p values at and just below .05 was greater than expected compared to p frequencies in other ranges. While this overrepresentation was found for values published in both 1965 and 2005, it was much greater in 2005. Additionally, p values close to but over .05 were more likely to be rounded down to, or incorrectly reported as, significant in 2005 than in 1965. Modern statistical software and an increased pressure to publish may explain this pattern. The problem may be alleviated by reduced reliance on p values and increased reporting of confidence intervals and effect sizes.

Searching the expressive face: evidence for both the right hemisphere and valence-specific hypotheses.

Quick and accurate judgments of emotional expressivity and attractiveness facilitate social interactions. Eye tracking was used to examine left/right asymmetries across 2 studies. Fixations to each hemiface, and to the eyes and mouth, when judging attractiveness and emotional expressivity were examined. Overall, more fixations occurred on the left hemiface (from the viewers point of view), even when mirror-reversed, supporting the suggestion that we intuitively know the left hemiface is more expressive. The right side of the mouth was fixated more when judging happiness, whereas the left eye was fixated more for sadness and the left mouth when rating emotional expressivity. The present findings support the notion that the right hemisphere and valence-specific hypotheses are not mutually exclusive. The right hemisphere hypothesis is supported when assessing global facial qualities (i.e., hemiface); however, hemispheric processing differences emerge when exploring the eyes and mouth. The current findings highlight the importance of not only considering how the face is examined more generally, but of also exploring smaller regions of interest to investigate lateral biases. Future research should therefore include analyses of fixations to the hemifaces, as well as to these smaller regions of interest.

The lighter side of advertising: Investigating posing and lighting biases

People tend to display the left cheek when posing for a portrait; however, this effect does not appear to generalise to advertising. The amount of body visible in the image and the sex of the poser might also contribute to the posing bias. Portraits also exhibit lateral lighting biases, with most images being lit from the left. This effect might also be present in advertisements. A total of 2801 full-page advertisements were sampled and coded for posing direction, lighting direction, sex of model, and amount of body showing. Images of females showed an overall leftward posing bias, but the biases in males depended on the amount of body visible. Males demonstrated rightward posing biases for head-only images. Overall, images tended to be lit from the top left corner. The two factors of posing and lighting biases appear to influence one another. Leftward-lit images had more leftward poses than rightward, while the opposite occurred for rightward-lit images. Collectively, these results demonstrate that the posing biases in advertisements are dependent on the amount of body showing in the image, and that biases in lighting direction interact with these posing biases.

Central fixations with rightward deviations: saccadic eye movements on the landmark task.

Neurologically normal individuals show an attentional bias toward the left side, which results from right hemisphere activation during visuospatial tasks. The strength of this bias is influenced by various factors, such as line length, vertical elevation and presentation time. What remains unknown is how participants gather information via saccadic eye movements during task performance and how this relates to their responses. Eye movements were recorded while participants performed the landmark task. Fixations and saccades were both analysed to gain a complete understanding of eye movement patterns. Fixations tended to focus on the centre of the line, with few left–right differences. Saccades were examined by creating histograms illustrating all x-coordinates which were examined over the course of each trial. Interestingly, mean eye position varied with participant response, with an overall tendency to look to the right of centre. Results are consistent with prior research, which has primarily looked at fixations and demonstrates the necessity of examining saccades as well as fixations in order to see how eye movement patterns relate to pseudoneglect.

Some participants may be better than others: Sustained attention and motivation are higher early in semester

Many studies use multiexperiment designs where experiments are carried out at different times of semester. When comparing between experiments, the data may be confounded by between-participants effects related to motivation. Research indicates that course-credit participants who engage in research early in semester have different personality and performance characteristics compared to those tested late in semester. This study examined whether the semester effect is caused by internal (inherent motivation of the participant) or external (looming exams, essays) factors. To do this, sustained attention and intrinsic/extrinsic motivation was measured in groups of course-credit (n = 40) and paid (n = 40) participants early and late in semester. While there was no difference in sustained attention between the groups early in semester, the course-credit group performed significantly worse late in semester. The course-credit group also showed a significant decrease in intrinsic motivation with time whereas the paid participants showed no change. Because changes were not seen for both groups, the semester difference cannot be due to external factors. Instead, the data demonstrate that course-credit participants who engage early have high sustained attention and intrinsic motivation compared to their late counterparts, who leave their participation to the last minute. Researchers who use multiexperimental designs across semester need to control for these effects—perhaps by using paid participants who do not vary across semester.

Directional collisions during a route-following task.

Neurologically normal people tend to collide with objects on the right side more frequently than with objects located on the left side of space. This phenomenon could be attributable to pseudoneglect wherein individuals selectively attend to the left field. The current study investigated this effect using a virtual route-following task that was presented centrally, in the lower field, and in the upper field. Handedness was also examined. Fifty-two participants (four left handed) completed this task, and when presented in the lower field, more left-side collisions emerged. In the upper condition, this bias reversed direction to the expected rightward bias. In the central condition, there was no significant directional bias in collision behavior. An interaction between handedness and presentation condition indicated that left-handed participants experienced more right-side collisions in the central condition. Collectively, these results suggest that directional biases (i.e., left vs. right) in collision behavior are modulated by both location in the visual field (central, upper, or lower) and handedness.

Keeping your distance: attentional withdrawal in individuals who show physiological signs of social discomfort.

Being in close social proximity to a stranger is generally perceived to be an uncomfortable experience, which most people seek to avoid. In circumstances where crowding is unavoidable, however, people may seek to withdraw their attention from the other person. This study examined whether social discomfort, as indexed by electrodermal activity, is related to a withdrawal of attention in 28 (m=8, f=20) university students. Students performed a radial line bisection task while alone or together with a stranger facing them. Physiological arousal was indexed by a wrist monitor, which recorded electrodermal activity. Correlational analyses showed that individuals who displayed physiological discomfort when together showed a withdrawal of the perceived midpoint of the line towards them (and away from the stranger). Conversely, individuals who showed no discomfort exhibited an expansion of the perceived midpoint away from them. We propose that participants shift their attention away from the stranger to increase interpersonal distance and reduce anxiety/arousal.

Do perceptual asymmetries differ in peripersonal and extrapersonal space

A space-based dissociation has been observed in clinical hemineglect, wherein neglect can be specific to either peripersonal or extrapersonal space. This same dissociation might occur in pseudoneglect, where both space-based and visual field differences have been observed. Upper and bottom visual field differences were examined within-subjects (N = 39), by presenting the greyscales task in both peripersonal and extrapersonal space. The leftward bias was strongest in the bottom visual field; however, no space-based differences were observed. It appears that perceptual biases differ between the upper and bottom visual fields, but this is not related to space-based perceptual biases.