Biomedical subjects

B R Fajen

Publications and source records attributed to B R Fajen.

2 recordsLinked to original sources

PubMed2001

Steering toward a goal by equalizing taus.

Steering toward a target can be controlled by equalizing the time-to-closure of the angle between the target and the direction of locomotion and the time-to-passage of the observer by the target. Two experiments required observers to steer through a computer-simulated environment toward a target depicted as either a floating cross that did not optically expand, a floating sphere that optically expanded or a grounded post that optically expanded. Experiment 1 revealed better performance in the post and sphere conditions, suggesting that steering is influenced by local optical expansion but not by perceived spatial target location or distance. Experiment 2 revealed differences in steering behavior between target types that suggested observers attempted to equalize time-to-closure and time-to-passage.

Adult↗

PubMed2000

Perceiving circular heading in noncanonical flow fields.

Five experiments examined circular heading perception with optical flows that departed from the canonical form. Noncanonicity was achieved through nonrigidity of the environment (Experiments 1 and 2), oscillations of the point of observation (Experiment 3), and the bending of light (Experiments 4 and 5). In Experiments 1 and 2, perception was impaired more by nonrigidity of the ground plane than by nonrigidity of the medium. In Experiment 3, perception was unimpaired by noncanonical flows induced by the bounce and sway of observer locomotion. In Experiments 4 and 5, perception was not impaired when light paths were distorted by a spherical projection, but perception was impaired when they were distorted by a sine function. Results are discussed in relation to the hypothesis that the information for perceiving heading is the ordinal pattern of optical flow.

Adult↗