Trans-saccadic integration for object recognition peters out with pre-saccadic object eccentricity as target-directed...

Area of Science:

• Cognitive Neuroscience
• Visual Perception
• Human Factors

Background:

• Object recognition is facilitated by bringing items to the fovea using saccades.
• Human observers integrate visual information from before (pre-saccadic) and after (post-saccadic) saccades.
• Previous studies used instructed saccades, limiting understanding of natural visual exploration.

Purpose of the Study:

• To investigate the limits of trans-saccadic integration during natural visual exploration.
• To determine how pre-saccadic eccentricity affects information integration for target recognition.
• To explore the role of central and peripheral vision in cluttered environments.

Main Methods:

• Thirty observers searched for a target in a large, cluttered visual scene (57.3°×33.8°).
• Participants freely decided when and where to saccade.
• Measured pre-saccadic eccentricity (e), pre-saccadic fixation duration (Tpre), and post-saccadic viewing duration (Tpost).

Main Results:

• Post-saccadic viewing duration (Tpost) increased with eccentricity (e) before saturating around 10°-20°.
• Pre-saccadic fixation duration (Tpre) increased slowly with e and decreased before saturation.
• At large eccentricities, trans-saccadic integration ceased, with recognition relying solely on post-saccadic foveal vision.

Conclusions:

• Trans-saccadic integration has limits, particularly in cluttered scenes during natural visual search.
• Beyond a critical eccentricity (ep), target identification depends exclusively on post-saccadic foveal processing.
• Findings align with the Central-peripheral Dichotomy, where central vision is for seeing and peripheral for looking.