Lorin J. Elias

Are Sex Differences in Navigation Caused by Sexually Dimorphic Strategies or by Differences in the Ability to Use the Strategies

When navigating, women typically focus on landmarks within the environment, whereas men tend to focus on the Euclidean properties of the environment. However, it is unclear whether these observed differences in navigational skill result from disparate strategies or disparate ability. To remove this confound, the present study required participants to follow either landmark- or Euclidean-based instructions during a navigation task (either in the real-world or on paper). Men performed best when using Euclidean information, whereas women performed best when using landmark information, suggesting a dimorphic capacity to use these 2 types of spatial information. Further, a significant correlation was observed between the mental rotation task and the ability to use Euclidean information, but not the ability to use landmark information.

Executive function moderates the intention-behavior link for physical activity and dietary behavior

Dominant theories of health behavior posit that social-cognitive and conative variables are sufficient to explain health behavior tendencies. The current studies challenge this assumption in two ways: (1) by demonstrating that unique variance in health protective behavior is predictable by knowing about individual differences in executive functioning, and (2) by demonstrating that executive function moderates the association between intention and behavior. In Studies 1 and 2, participants completed a computer-based task of executive function (Go/NoGo task) and articulated 1-week behavioral intentions for physical activity (Study 1) and dietary behavior (Study 2). Hierarchical regression analyses revealed that executive function predicts unique variance in both behaviors, and strongly moderates the association between behavioral intention and behavioral performance. Together behavioral intention and executive function explain more variance in health protective behavior than ‘rational actor’ models that have been widely adopted and disseminated.

Dissociating semantic and perceptual components of synaesthesia: behavioural and functional neuroanatomical investigations

Colour digit synaesthetes experience atypical dual perceptions wherein achromatic digits are perceived along with coloured photisms. Recent studies have employed Stroop or priming tasks and exhibited interference or facilitation in synaesthesia [Nature 410 (2001) 580-582; Perception 28 (1999) 651-664]. We compared a synaesthete to a semantic control with arbitrary colour-number associations and demonstrated that these tasks do not elicit effects unique to synaesthesia. In contrast, we present functional neuroimaging data that clearly differentiates between these two conditions.

Neurocognitive Influences on Health Behavior in a Community Sample

CONTEXT Dominant models of individual health behavior omit biological variables entirely and are composed almost exclusively of social-cognitive and conative variables. Research from the neurosciences suggests a role for brain function in explaining behaviors that require active self-regulation for consistent performance. However, the association between brain function and health behavior is underexplored. OBJECTIVE To examine the predictive power of executive function for 2 health risk behaviors and 2 health protective behaviors in healthy adults. DESIGN A cross-sectional community sample (N = 216) of adults 20-100 years of age were administered a battery of neuropsychological tests and completed self-report questionnaires regarding their health practices. It was hypothesized that poor performance on neuropsychological tests tapping executive function would be associated with poor health behavior tendencies. RESULTS Errors on the Stroop task were positively associated with health risk behavior and negatively associated with health protective behavior after controlling for demographics, education, and IQ. CONCLUSION Executive function is associated with health behavior tendencies. If the association is causal, explanatory models of individual health behavior should be revised to account for individual differences in biologically imbued self-regulatory abilities.

Males and females scan maps similarly, but give directions differently

After studying routes on a map, females tend to give directions that feature landmarks and left/right turns, whereas males include more cardinal and distance information. It is plausible this difference results from disparate attention to these features during exploration of a map. In the present study, 22 males and 22 females learned routes on a map while their eye movements were monitored, and then gave written directions between different locations. Consistent with earlier research, males made more references to NSEW when giving directions, whereas females referred mainly to left/right turns and landmarks along each route. However, these reporting biases were not related to differences in how the groups explored the maps, as females did not spend more time looking at landmarks, nor did either group spend more time looking at Euclidean cues. Thus, despite sexually dimorphic route descriptions, there was not dimorphic exploration or attention to the salient features.

Sex differences in the effect of articulatory or spatial dual-task interference during navigation.

Women are more likely to employ landmark-based strategies when navigating, and they are superior at employing this type of strategy. The cause of this sexually dimorphic behaviour is unknown. Seventy-nine undergraduates performed a matrix navigation task wherein the symbols within the matrix were highly nameable. Participants were either given landmark-based or Euclidean-based instructions for navigation within the matrix. During navigation, participants were subjected to either articulatory or spatial interference. The articulatory interference selectively impaired womens ability to navigate correctly, regardless of the type of instruction. The performance of the men was not affected differentially by the two types of interference. When given a test of symbol recognition following the navigation task, women recognized more of the symbols employed in the task. Collectively, this result suggests that women rely on linguistic information more than men do when navigating, regardless of the type of instruction.

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.

Female advantage for spatial location memory in both static and dynamic environments.

A female advantage has previously been found for spatial location tests of object memory. Previous studies have used static, 2-D tasks to test this advantage. This study used a computerized adaptation of the game Concentration to test object location memory in both a static and dynamic array of 24 pairs of line drawings. The dynamic version of this task was used to better reflect the dynamic real world in which we usually use object location memory. Consistent with previous research, we observed a female advantage. This advantage was found to a similar extent in both the static and dynamic versions of the task. The female advantage for object location memory is a concrete advantage in spatial cognition that females show on the Concentration Task, regardless of the nature of the presentation environment.

Lateral and sex differences in manual gesture during conversation

To examine whether sex differences in cerebral lateralisation for speech can be observed through lateral differences in manual gesturing during natural conversation, 100 individuals (50 male and 50 female) were observed following a procedure similar to that described by Kimura (1973a,b). For males, there was a significant increase in the number of gestures made with the right hand during speech. When males were listening, there was a significant increase in the number of gestures made with the left hand. This result was not observed in the females studied, who did not demonstrate significant manual asymmetries in gesturing during either speech or listening. This result is consistent with claims that there is a sex difference in hemispheric specialisation wherein males are more functionally lateralised than females.

Handedness and Depression in University Students: A sex by handedness interaction

Previous research has indicated that there is an increased incidence of left-handedness in samples of depressed individuals. We administered the Beck Depression Inventory (BDI) to a sample of 541 undergraduate students. Left-handed males showed significant elevation of BDI scores. It is unlikely that this result is due to decreased right hemisphere activity or sex-role conflicts. However, one possibility is that known differences in male steroid hormones levels between right- and left-handers contributed to this effect. Press