Meaningful images produce stronger saccadic adaptation
56.4115, Tuesday, 19-May, 2:45 pm - 6:45 pm, Pavilion
Annegret Meermeier1,2, Svenja Gremmler1,2, Markus Lappe1,2; 1Department of Psychology, University of Muenster, Muenster, Germany, 2Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, Muenster, Germany
Saccades are made to scan interesting objects in the environment with foveal vision. In the lab, however, they are usually studied with meaningless point targets. Recent experiments showed that vision of a meaningful target affects saccade kinematics, accuracy, and latency. We investigated whether saccadic adaptation, a gradual change of amplitude when the target is shifted during the saccade, is affected by the content of the target. We expected that the motivation to land accurately on a target may be stronger if the target was not a point but a meaningful picture. Thirty-four subjects (27 female) participated in a scanning outward adaptation experiment in which 4 targets (1.8°x2.8°) in rectangular arrangement had to be viewed successively. One of the targets was a small image of a human figure. A control target contained random noise matched for luminance and spatial frequency. The stimulus set shifted in saccade direction during each horizontal saccade by 33% of the initial target distance (12°). In different conditions, stimuli either remained visible throughout the experiment, or were masked after saccade onset, or 200 ms later. Adaptation was quantified by computing the Gain Change (GC) ((amplitudelate-amplitudepre)/initial target distance) for each subject, which was then averaged according to experimental condition. The results showed that saccadic adaptation was greater for saccades directed towards meaningful pictures than towards noise (GChuman 14.14 %, GCnoise 10.83 %). This was also true when the images were masked 200ms after saccade onset such that only a brief glimpse could be obtained (GChuman 13.13%, GCnoise 09.68 %). When images were masked at saccade onset, no significant difference in adaptation was observed (GChuman 10.48%, GCnoise 10.76 %). We conclude that the post-saccadic view of a meaningful image at the saccade landing position facilitates saccadic adaptation.