Changes in the functional visual field during search with and without eye movements.

Area of Science:

• Visual perception and attention research.
• Cognitive neuroscience and psychophysics.

Background:

• The functional visual field (FVF) is not static and varies with attentional demands during visual exploration.
• Understanding FVF dynamics is crucial for explaining visual search efficiency.

Purpose of the Study:

• To investigate how eye movements and item density influence the size of the functional visual field (FVF).
• To determine if search efficiency is affected by FVF size under different search conditions.

Main Methods:

• Performance measures of the FVF were used during visual search tasks.
• Tasks included search with and without eye movements, varying item density.
• Subjective reports and eye-tracking data were analyzed.

Main Results:

• The FVF is significantly smaller during search with eye movements compared to search without eye movements.
• FVF size is consistently constrained by the density of distracting items.
• Without eye movements, the FVF expands over time, indicating covert attention shifts and individual spatial biases.
• Item inspection rate remains constant across conditions when stimulus density is considered.
• Set size effects disappear when stimulus density is factored in, supporting the cortical separation hypothesis.

Conclusions:

• Eye movements dynamically alter the functional visual field, generally reducing its effective size.
• Distractor density is a primary factor limiting FVF size and visual search performance.
• The findings support a spatial constraint model of the FVF, potentially linked to cortical processing limitations.