Fig. 1.

Modified backstep paradigm used in the present study and behavioral results. A: examples of typical horizontal eye position traces for trials early in the adaptation phase. Gray lines represent target position. Left (blue): the classic backstep paradigm with a backward target step during the saccade, which induces a backward corrective saccade (data from Srimal et al. 2008). Right (red): in our modified paradigm, the backstepped target was presented for only 160 ms and then was placed 0.5° to the left of fixation. B: amplitude of corrective saccades as a function of the trial number across all participants. Mean amplitude was calculated with a sliding window of 10 trials. Shaded areas correspond to ±1 SD. Blue curve corresponds to values obtained with the classic backstep paradigm (data from Srimal et al. 2008) and red curve to values obtained with our modified backstep paradigm. Note how the amplitudes of corrective saccades track learning only in the classic version. C: saccade gain as a function of trial number for a representative participant. An experimental session was divided into 5 phases of 50 trials each: Preadapt, Adapt (A1, A2, A3), and Deadapt. Thin dashed horizontal lines demark the amplitude of the target. Thick solid horizontal lines correspond to mean saccade gain for each phase. Note how saccade gain decreases in each Adapt phase and then rebounds in the Deadapt phase. D: distribution of saccade gain changes from Preadapt to A3 phases for each participant.