Abstract
Saccade accuracy is maintained by a learning mechanism called saccade adaptation. Previous studies used singular stimuli and found that erroneous saccades are only corrected when feedback about their accuracy is available shortly after movement offset (e.g., Bahcall & Kowler, 2000). However, naturalistic environments can be filled with many dynamic objects and saccade adaptation has to use the right object at the right time to maintain saccade accuracy in an ever-changing world. Although a previous study showed that delayed feedback, available only long after saccade offset, can drive saccade adaptation if it is task-relevant (Wagner et al., 2021), it is currently unknown how delayed feedback from relevant stimuli interacts with conflicting feedback signals from temporarily proximate irrelevant stimuli. We instructed participants to make a vertical saccade towards an unfilled circle. Inside the circle, two squares were shown for 150 ms each, successively at opposite locations: The first square appeared upon saccade detection and the second square appeared 200 ms after the offset of the first square. Participants were instructed that they either have to discriminate which side of the first (discriminate-first-condition) or the second square (discriminate-second-condition) had a gap. We observed saccade adaptation towards the first square in the discriminate-first-condition. However, no adaptation to either square was observed in the discriminate-second-condition; instead, primary saccades were directed to the center of the circle and additional secondary saccades were used to bring gaze close to the location of the second square. Importantly, this was not due to the oculomotor system ignoring delayed feedback: Saccade adaptation was observed in a control condition, where only the second square was shown. We conclude that saccade adaptation can suppress signals from irrelevant stimuli. However, delayed postsaccadic accuracy feedback is not obligatory used for saccade adaptation if multiple, temporally proximate error signals are available around saccade offset.