Serial dependencies in motor targeting as a function of target appearance

Area of Science:

• Neuroscience
• Vision Science
• Oculomotor Research

Background:

• Saccadic eye movements are crucial for directing gaze.
• Post-saccadic errors, deviations in eye movement landing position, trigger immediate adjustments.
• The mechanism of saccadic adaptation, particularly the role of target certainty, requires further investigation.

Purpose of the Study:

• To investigate whether saccadic recalibration integrates target certainty.
• To determine if the impact of post-saccadic errors depends on the certainty of the current target.
• To explore how pre-saccadic target features influence adaptation to post-saccadic errors.

Main Methods:

• Subjects performed saccades towards Gaussian blob targets with manipulated spatial certainty (size) and contrast.
• Post-saccadic target displacement was introduced to create errors.
• Certainty was manipulated for pre-saccadic and post-saccadic targets in separate sessions.
• Target contrast was also manipulated, sometimes mid-saccade.

Main Results:

• Saccade amplitude reductions occurred only when the target was currently uncertain.
• Adaptation was observed when the pre-saccadic target was certain and target contrast remained constant.
• Pre-saccadic target features significantly modulated the influence of post-saccadic errors on saccade amplitude.

Conclusions:

• Saccadic adaptation is influenced by the certainty of the visual target.
• The characteristics of the pre-saccadic target, specifically its size and contrast, are key determinants of how post-saccadic errors shape subsequent saccade amplitudes.
• This suggests an integration process where target uncertainty modulates error-driven recalibration.