Eye movements reveal distinct encoding patterns for number and cumulative surface area in random dot arrays

Area of Science:

• Cognitive psychology
• Neuroscience
• Visual perception

Background:

• The Approximate Number System (ANS) allows rapid, intuitive estimation of object quantities.
• The exact computational mechanisms underlying visual number encoding remain debated.
• Theories propose either dedicated enumeration or inference from non-numerical visual features.

Purpose of the Study:

• To differentiate between dedicated number encoding and feature-inference theories.
• To investigate if number and cumulative area perception utilize distinct visual encoding computations.
• To identify task-specific saccadic signatures during number and area discrimination.

Main Methods:

• Participants performed both number and cumulative area discrimination tasks.
• Eye-movements (saccades) were tracked during task performance.
• Visual stimuli were identical across number and area tasks to isolate encoding differences.

Main Results:

• Discriminating number versus area significantly modulated eye-movement patterns.
• Number tasks involved more numerous, shorter saccades with frequent target switching.
• Area tasks showed fewer, longer saccades, focusing on larger visual extents.

Conclusions:

• Distinct saccadic signatures support separate encoding algorithms for number and cumulative area.
• Visual number and area are processed through different computational pathways.
• Eye-movement analysis provides a valuable tool for dissecting cognitive encoding processes.