Lack of bilateral generalization of adaptation to auditory rearrangement

Intermanual transfer of adaptation to rearranged ear-hand coordination, generated by exposure to auditory rearrangement entailing 30 deg of functional rotation of the interaural axis by electronic pseudophones, was explored using 16 Ss. The results show that, except for one exposure condition, changes in ear-hand coordination that compensate the distortion induced by the pseudophones fail to transfer intermanually. These findings are similar to observations on visual adaptation.     

Effective luminance contrast as a parameter in contingent aftereffects

Variation in the magnitude of contingent aftereffects was explored as a function of the luminance contrast ratio profile of inspection stimuli. Positive contrast stimuli (chromatic bars interspersed with achromatically brighter bars) produced substantially attenuated aftereffects compared with negative contrast stimuli (chromatic and dark bars). This attenuation was hypothesized to result from retinal image deterioration of positive contrast gratings due to retinal reflection/scatter. In a second experiment, subjects selected for their light retinal pigmentation manifested substantial enhancement of the asymmetry between the aftereffects generated by positive and negative contrast gratings. Those with dark fundus pigmentation showed symmetrical aftereffects.     

Orientation-specific luminance aftereffects

Prolonged viewing of bright vertical (horizontal) gratings alternating with dim horizontal (vertical) gratings generates negative brightness aftereffects that are contingent on the orientation of orthogonal test gratings. The effect is measured by a brightness cancellation technique, similar to the color cancellation technique used in measuring McCollough effects. Like the latter, brightness aftereffects appear to persist for long periods. The magnitude of these aftereffects is a positive monotonic function of the luminance difference between the inducing gratings, and it depends on the conditions of induction; monocular induction generates larger aftereffects than binocular induction does. The aftereffect transfers interocularly, although its magnitude in the contralateral eye is substantially attenuated; binocular measurement, following monocular induction, results in even smaller aftereffects. An attempt to understand these findings within the computational model of brightness perception developed by Grossberg and Mingolla (1985a, 1985b) is presented.     

The role of acceleration information in prism adaptation

Two experiments were performed in which the acceleration component of limb movement information during prism exposure was manipulated, by controlling the trajectory and visibility of arm movement. When limb movements were confined to a lateral motion on a linear track, adaptation was evident when arm movement reversal at the end of the trajectory could be viewed (nonoccluded arm-movement reversal conditions). No adaptation occurred in the occluded arm-movement reversal condition. When movements were made on a curved track, adaptation was evident in both the nonoccluded and the occluded arm-movement reversal conditions. The results indicate that the acceleration component of reafferent stimulation may be critical in prism adaptation when no error information is available.     

Movement-induced modulation of orientation-specific color aftereffects

The intensity of the McCollough effect is modified when, following exposure to the inducing chromatic stimuli, the achromatic test gratings are seen oscillating orthogonally to their orientations. Green aftereffect seen on stationary test gratings is enhanced by oscillations, while pink aftereffect present on the stationary gratings fades upon oscillation of the test stimulus. These opponent changes are tentatively accounted for in terms of an interaction between Fechner-Benham type induced color and processes that mediate the orientation-specific chromatic aftereffects.     

A technique for measuring eye-foot coordination without visual guidance

A device for studying adaptation to rearranged eye-foot coordination is described. The technique allows measurement of changes in the localization of a target with the foot without visual guidance of the responding limb.     

Psychology of computer use: IV. Effects of video display units on fundamental visual processes: temporal resolution

Measures of two-pulse resolution (2PR) using foveally and peripherally viewed targets were obtained before and after reading videotext and print. Three pulse durations (25, 250, and 300 msec.) were used. The results showed that (a) 2PR on the fovea is about a fourth of that on the periphery, (b) peripheral 2PR increases following reading videotext, and (c) no appreciable effects occur following reading print.     

Adaptation to rearranged eye-foot coordination

The generality of adaptation following three types of movements during prism exposure was investigated. The three exposure conditions consisted of (1) walking with prisms, (2) viewing leg movements through prisms, and (3) viewing arm movements through prisms. The results showed that changes in eye-foot coordination and egocentric localization occur following both (1) and (2). Exposure Conditions 2 and 3 both produce changes in eye-hand coordination; however, eye-foot coordination was found unaltered following (3).