Submitted on September 14, 2007
Accepted on January 25, 2008
Obligatory adaptation of saccade gains
Riju Srimal1, Joern Diedrichsen2, Edward Boris Ryklin1, and Clayton E Curtis3*
1 Center for Neural Science, New York University, New York, New York, United States
2 School of Psychology, University of Wales, Bangor, gwynedd, United Kingdom; , United Kingdom
3 Psychology, New York University, New York, New York, United States
* To whom correspondence should be addressed. E-mail: clayton.curtis{at}nyu.edu.
We tested the hypothesis that saccade gains adapt to minimize error between the visual target and the saccade endpoint of every saccade we make even when the errors on sequential saccades are not directionally consistent. We utilized a state-space model that estimated the degree to which saccade gains were modified by the magnitude and direction of errors made on the previous trial. Importantly, to show that learning did not depend on the accumulation of directionally consistent errors, we fit the model to saccades made to targets that were displaced in a random direction during the saccade, thereby inducing errors whose directions were not sequentially the same. Saccade gains clearly adapted on a trial-by-trial basis despite that the perturbations were random, and the average amount of learning per trial was of similar magnitude as that found in a constant displacement of the target. These results indicate that saccade adaptation is a rapid and obligatory process that does not require conscious awareness.
