Distance estimation is influenced by encoding conditions.

Area of Science:

• Visual perception
• Human psychophysics
• Computational neuroscience

Background:

• Foveating relevant visual information enhances localization.
• Peripheral vision exhibits increased positional uncertainty with eccentricity.
• The impact of foveal versus peripheral encoding on spatial interval estimation remains unclear.

Purpose of the Study:

• To compare spatial interval estimation accuracy between foveal and peripheral visual encoding conditions.
• To investigate how gaze direction influences the perception of distance between visual stimuli.

Main Methods:

• Participants estimated the distance between two co-planar dots after a delay.
• Two conditions were tested: foveating the dots versus fixating centrally while viewing dots peripherally.
• Stimulus presentation involved a reference dot and a movable pointer for reproduction.

Main Results:

• Distance estimation error was small but increased with separation when dots were foveated.
• Peripheral encoding led to significant overestimation for smaller separations.
• Peripheral and foveal estimation performance became comparable for larger separations (10-16 degrees).

Conclusions:

• Improved foveal accuracy stems from reduced estimation bias, not solely reduced positional uncertainty.
• Evidence supports an explanation based on activated neuronal populations and inhibitory interactions.
• Simulations incorporating receptive field size differences support the proposed neural mechanism.