Adaptation of Saccades and Perceived Size after Trans-Saccadic Changes of Object Size.
When saccadic eye movements consistently fail to land on the intended target, saccade accuracy is maintained by gradually adapting the amplitude of successive saccades to the same target. Such saccadic adaptation is usually induced by systematically displacing a small visual target during the execution of the saccade. However, saccades are normally performed to extended objects. Here we report changes in saccade amplitude when the size of a target object is systematically changed during a saccade. Moreover, we find that this manipulation also affected the visual perception of the size of that object. Human subjects were tested in shortening and lengthening adaptation where they had to make saccades to targets of different sizes, which were each shortened or lengthened during saccade execution, respectively. In both experiments, a preadaptation and postadaptation phase required manually indicating the horizontal size of each target by grip aperture and, in a further experiment, a verbal size report. We evaluated the effect of change in visual perception on saccade and on the two modalities of judgment. We observed that (1) saccadic adaptation can be induced by modifying target object size and (2) this gradual change in saccade amplitude in the direction of the object size change evokes a concomitant change in perceived object size. These findings suggest that size is a relevant signal for saccadic system and its trans-saccadic manipulation entails considerable changes at multiple levels of sensorimotor performance.
Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy, and.
Annalisa
http://orcid.org/0000-0003-3032-9571
A
Bosco
Department of Psychology, University of Munster, D-48149 Munster, Germany.
Markus
M
Lappe
Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy, and patrizia.fattori@unibo.it.
Patrizia
http://orcid.org/0000-0002-0079-3755
P
Fattori
D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D005260:Female; D006801:Humans; D007600:Judgment / Q000502:physiology; D008297:Male; D010775:Photic Stimulation; D011597:Psychomotor Performance; D011930:Reaction Time; D012438:Saccades / Q000502:physiology*; D012858:Size Perception / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult
eye movements; oculomotor control; perception; vision