Visual-auditory interstimulus contingency effects in saccade programming

This thesis investigated the effects of visual-auditory interstimulus contingencies on the latencies and amplitudes of saccadic eye movements. In a new experimental procedure, the interstimulus contingencies were defined in the locations of a target and an accompanying stimulus rather than in the mere presence or absence of the stimuli. Human subjects were asked to make a saccade to a visual target and to use the location of an auditory accompanying stimulus as a possible, but unreliable cue for the location of the visual target. We investigated several different types of saccades. The latencies of reflexive visual prosaccades did not show contingency effects. However, in a bimodal go/no-go task the contingency did reach significance indicating shorter latencies in the positively and negatively correlated conditions than in the control condition. It was concluded that these effects were specific to the go/no-go task, because in experimental tasks which involved the choice in saccade direction the saccade latencies in the unlikely condition were longer than in the control condition. This result was true for visual antisaccades, auditory prosaccades and visual prosaccades with outline boxes. We therefore conclude that the processing of interstimulus contingencies requires the choice in saccade direction and thus leads to shorter latencies to targets at the likely location and longer latencies to targets at the unlikely location. The choice in saccade direction was implemented in a new, per interval linear approach to threshold (ILAT) model. Simulations of the model gave a good fit to the mean saccadic latencies of auditory prosaccades. The model parameters were in good accord with neurobiological evidence.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Oldenburg

Year

2001

Author dc:creator

• Kirchner, Holle

• [Keine Schlagwörter von Autor/in vergeben.]

Repository record source_url

http://oops.uni-oldenburg.de/281

OAI identifier oai:identifier

oai:oops.uni-oldenburg.de:281