The peripheral sensitivity profile at the saccade target reshapes during saccade preparation

Area of Science:

• Neuroscience
• Cognitive Science
• Vision Science

Background:

• Goal-directed eye movements (saccades) are crucial for bringing objects into clear foveal vision.
• Pre-saccadic attention shifts may enhance visual perception, particularly for high spatial frequencies (SFs).
• Previous research focused on narrow SF ranges, potentially missing broader effects on visual sensitivity profiles.

Purpose of the Study:

• To investigate how saccade preparation impacts the shape of the visual sensitivity profile across a wider range of spatial frequencies (SFs).
• To determine if pre-saccadic enhancement varies for different SFs and how this relates to changes in the sensitivity profile.

Main Methods:

• Observers discriminated the orientation of sinusoidal gratings (probes) at saccade targets (10 degrees visual angle eccentricity).
• Probe SFs varied unpredictably from 1 to 5.5 cycles per degree (cpd).
• Response accuracies across SFs were fitted to a log-parabolic (inverted U-shaped) function to model the sensitivity profile.

Main Results:

• Before saccade onset, the sensitivity profile peaked at 0.6 cpd with a broad bandwidth.
• During saccade preparation, the profile's peak shifted to higher SFs, and its bandwidth decreased.
• Pre-saccadic enhancement increased with SF up to 2.5 cpd, but less so for higher SFs.

Conclusions:

• Pre-saccadic enhancement is influenced by an SF's position on a broader, dynamic sensitivity profile.
• Saccade preparation significantly reshapes this profile, shifting the peak towards higher SFs.
• This reshaping improves visual resolution at the saccade target, even for unpredictable visual features.