Showing papers by "Werner X. Schneider published in 2002"

Transsaccadic memory of position and form

Abstract: Why and how people perceive the visual world as continuous and stable, despite the gross changes of its retinal projection that occur with each saccade, is one of the classic problems in perception. In the present paper, we argue that an important factor of visual stability and transsaccadic perception is formed by the reafferent visual information, i.e., the visual display that is present when the eyes land. After a review of some of the relevant theoretical, behavioural and physiological research on space constancy, saccadic suppression and transsaccadic memory, three experiments are presented. In a first experiment, we study the effect of an extended horizontal bar covering the target area for a short period after the saccade on saccadic suppression of image displacement. The results show that the bar acts just like a temporary blanking of the saccade target, leading to a strong reduction of saccadic suppression. In the second experiment, we show that any object that is present immediately after the saccade can establish a spatial reference, even if it is dissimilar to the saccade target. In a third experiment we study, with a similar approach, the effect of blanking and postsaccadic information on transsaccadic integration of form information. The data demonstrate that a localized postsaccadic object tends to replace the content of transsaccadic memory.

Visual attention and manual response selection: Distinct mechanisms operating on the same codes

Abstract: In four experiments, participants made a speeded manual response to a tone and concurrently selected a cued visual target from a masked display for later unspeeded report. In contrast to a previous study of H. Pashler (1991), systematic interactions between the two tasks were obtained. First, accuracy in both tasks decreased with decreasing stimulus (tone-display)‐onset asynchrony (SOA)— presumably due to a conflict between stimulus and response coding. Second, spatial correspondence between manual response and visual target produced better performance in the visual task and, with short SOAs, in the tone task, too—presumably due to the overlap of the spatial codes used by stimulus- and response-selection processes. Third, manual responding slowed down with increasing SOA—reflecting either a functional bottleneck or strategic queuing of target selection and response selection. Results suggest that visual stimulus selection and manual response selection are distinct mechanisms that operate on common representations. The present paper deals with the relationship and possible interactions between two human control processes, one concerned with the selection of environmental stimulus information and the other with the voluntary selection of