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H Wiesenfelder

Publications and source records attributed to H Wiesenfelder.

4 recordsLinked to original sources

Binocular rivalry suppression disrupts recovery from motion adaptation.

The motion aftereffect (MAE) lasts longer when the test period does not immediately follow adaptation, a phenomenon called storage. Does storage of the MAE occur if the test target is present but rendered phenomenally invisible owing to the presence of a rival target presented to the other eye during the storage period? Our experiment addressed this question. Following adaptation to a drifting grating, an intervening period preceded testing with a stationary grating. During this period, the adapted eye either viewed the test target immediately or was occluded, and the unadapted eye either viewed a high-contrast rival target or was occluded. Thus four conditions were employed. The duration of the residual MAE was found to be longer for the rivalry condition (grating and rival target viewed) than for the normal MAE condition (grating viewed), and comparable to that in the stored MAE condition (both eyes occluded). Thus, the MAE is stored when the test target is rendered invisible due to binocular rivalry, indicating that a suppressed target is ineffective at promoting decay of the MAE. So while suppression does not prevent information about the adapting grating from reaching the site of generation of the MAE (Lehmkuhle & Fox, 1975), it can prevent information about the test target from reaching the site of the stored MAE. Current models attribute the MAE to reduced responsiveness of direction-selective cortical neurons (Sutherland, 1961; Barlow & Hill, 1963). Thus, storage should reflect a differential return of these adapted cells to preadapted response levels, dependent on postadaptation stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Ocular↗

Apparent motion can survive binocular rivalry suppression.

For short-range motion, observers dichoptically viewed a random-dot cinematogram and a rival target. Upon keypress, the first frame of the cinematogram was replaced by the second frame. Observers judged the direction of motion, which was governed by the initial position of the central region. Performance was well above chance during both dominance and suppression. For long-range motion, observers rated the motion produced by sequentially flashing two small spots, with the first spot contained within a rivalrous region. Suppression reduced but did not prevent perception of this motion. Presenting the second motion frame to both eyes weakened both forms of motion.

Female↗

The neural site of binocular rivalry relative to the analysis of motion in the human visual system.

Neural processing is disrupted during suppression phases of binocular rivalry, as evidenced by the temporary invisibility of an otherwise complex, high-contrast visual stimulus. This paper investigates the locus of this disruption relative to the processing of information about image motion. In one experiment, observers tracked binocular rivalry between a stationary textured field and a plaid composed of 2 drifting cosine gratings, with the angle between components varied to produce different pattern speeds. (Plaid speed is given by the ratio of the component speed to the cosine of the angle between the 2 directions of motion.) Predominance of the moving plaid increased with pattern speed, even though the speed of the individual components remained constant. Control measures verified that this influence of plaid speed was not attributable to specific component orientations. Information about coherent motion influences the rivalry process, implying that the site of coherent motion analysis, presumably the middle temporal area (MT), received input during dominance phases of rivalry. A second experiment investigated the effect of suppression on the processing of complex, nonlinear motion. Observers tracked rivalry phases for a rotating spiral, then indicated the duration of the subsequently perceived spiral aftereffect (SAE) for both rivalry and nonrivalry conditions. The SAE was reduced when adaptation occurred under the rivalry condition, with aftereffect duration proportional to the total duration of spiral visibility during adaptation. Earlier work places rivalry after the site of the linear motion aftereffect, and the present results show that rivalry suppression occurs prior to the site of spiral motion processing.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Ocular↗