Asymmetries and idiosyncratic hot spots in crowding

Area of Science:

• Visual perception
• Neuroscience
• Psychophysics

Background:

• Crowding is a phenomenon in visual perception where the identification of a target is impaired by nearby stimuli.
• Several asymmetries in crowding have been previously reported, but their systematic exploration across the entire visual field is limited.

Purpose of the Study:

• To systematically investigate crowding asymmetries across the visual field.
• To explore individual variations in crowding strength and their relationship with visual acuity.
• To determine the effect of attention allocation on crowding asymmetries.

Main Methods:

• Measured crowding strength for Gabor targets at 16 positions (8 directions, 2 eccentricities) in the visual field.
• Used a plaid mask positioned inward, outward, clockwise, or counter-clockwise relative to the target.
• Compared crowding strength across different visual field locations and under varying attentional demands.

Main Results:

• Revealed significant individual variations in crowding strength, forming idiosyncratic hotspots.
• Found no correlation between individual crowding variations and visual acuity.
• Confirmed previously reported crowding asymmetries, with the inward-outward asymmetry specifically observed along the horizontal meridian.
• Demonstrated a two-fold increase in inward-outward crowding asymmetry when observers attended to both visual fields.

Conclusions:

• Crowding exhibits substantial individual differences unrelated to visual acuity.
• The inward-outward crowding asymmetry is restricted to the horizontal meridian.
• Attention allocation plays a critical role in modulating crowding asymmetry, suggesting its influence on visual processing beyond simple stimulus interactions.