Judgments of path, not heading, guide locomotion

To steer a course through the world, people are almost entirely dependent on visual information, of which a key component is optic flow. In many models of locomotion, heading is described as the fundamental control variable; however, it has also been shown that fixating points along or near one's future path could be the basis of an efficient control solution. Here, the authors aim to establish how well observers can pinpoint instantaneous heading and path, by measuring their accuracy when looking at these features while traveling along straight and curved paths. The results showed that observers could identify both heading and path accurately (approximately 3 degrees ) when traveling along straight paths, but on curved paths they were more accurate at identifying a point on their future path (approximately 5 degrees ) than indicating their instantaneous heading (approximately 13 degrees ). Furthermore, whereas participants could track changes in the tightness of their path, they were unable to accurately track the rate of change of heading. In light of these results, the authors suggest it is unlikely that heading is primarily used by the visual system to support active steering.     

Controlling steering and judging heading: retinal flow,visual direction,and extraretinal information

The contribution of retinal flow (RF), extraretinal (ER), and egocentric visual direction (VD) information in locomotor control was explored. First, the recovery of heading from RF was examined when ER information was manipulated; results confirmed that ER signals affect heading judgments. Then the task was translated to steering curved paths, and the availability and veracity of VD were manipulated with either degraded or systematically biased RF. Large steering errors resulted from selective manipulation of RF and VD, providing strong evidence for the combination of RF, ER, and VD. The relative weighting applied to RF and VD was estimated. A point-attractor model is proposed that combines redundant sources of information for robust locomotor control with flexible trajectory planning through active gaze.     

Internationalizing 360-Degree Feedback: Are Subordinate Ratings Comparable?

ABSTRACT: This study addressed whether 360-degree feedback ratings made by subordinates are equivalent across national cultures (Great Britain, Hong Kong, Japan, U.S.). Employees ratings of their leaders were collected via a companys existing 360-degree feedback survey. A two-factor baseline model was developed using exploratory factor analysis and tested across cultures utilizing confirmatory factor analysis techniques. Results revealed differences in factor form, suggesting that the constructs underlying the survey and their relationship to the survey items differed across cultures. These results emphasize the need for multinational companies to use caution when transporting human resources practices, such as 360-degree feedback, to international locations.The author would like to express appreciation to Alice Stuhlmacher for her valuable comments on earlier versions of this article. This research was conducted as part of the authors doctoral dissertation. Portions of this article were presented at the 17th Annual Conference of the Society for Industrial and Organizational Psychology, Toronto, Ontario, Canada, April 2002.     

The role of visual and nonvisual information in the control of locomotion

During locomotion, retinal flow, gaze angle, and vestibular information can contribute to one's perception of self-motion. Their respective roles were investigated during active steering: Retinal flow and gaze angle were biased by altering the visual information during computer-simulated locomotion, and vestibular information was controlled through use of a motorized chair that rotated the participant around his or her vertical axis. Chair rotation was made appropriate for the steering response of the participant or made inappropriate by rotating a proportion of the veridical amount. Large steering errors resulted from selective manipulation of retinal flow and gaze angle, and the pattern of errors provided strong evidence for an additive model of combination. Vestibular information had little or no effect on steering performance, suggesting that vestibular signals are not integrated with visual information for the control of steering at these speeds.     

Takin’ It to the Streets: Approach/Avoidance Motivation in the Lives of At-Risk Youth

An attempt is made in this article to relate creativity to personality in a much more definitive way than has been done previously and to use the known correlates of personality to suggest a theory of creativity that would explain many of the phenomena associated with this concept. A causal chain is suggested reaching from DNA to creative achievement, based largely on experimental findings not usually considered in relation to creativity (e.g., latent inhibition). Inevitably, the model is highly speculative, but it is testable and hence may prove useful in not only accounting for many observations and experimental results but also in suggesting new experiments and observations.     

Default Probability

A probability may be called “default” if it is neither derived from preestablished probabilities nor based on considerations of frequency or symmetry. Default probabilities presumably arise through reasoning based on causality and similarity. This article advances a model of default probability based on a featural approach to similarity. The accuracy of the model is assessed by comparing its predictions to the probabilities provided by undergraduates asked to reason about mammals.