Attentional modulation of size perception in peripheral vision

Area of Science:

• Visual perception
• Neuroscience
• Psychophysics

Background:

• The size-eccentricity effect describes how perceived object size shrinks with distance from central vision.
• This is linked to cortical magnification, where central vision is overrepresented.
• The role of endogenous attention in modulating this effect is unclear.

Purpose of the Study:

• To investigate if endogenous attention lessens or worsens the size-eccentricity effect.
• To determine how attention influences the perception of size in peripheral vision.

Main Methods:

• Ten participants performed a size comparison task with peripheral stimuli at varying eccentricities.
• Endogenous attention was directed using cued locations (70% valid).
• Psychometric functions quantified perceived size via point of subjective equivalence.

Main Results:

• A significant size-eccentricity effect was observed: peripheral objects were underestimated.
• Endogenous attention, especially with valid cues, attenuated this underestimation, particularly at higher eccentricities.
• Attention improved perceptual sensitivity, indicated by steeper psychometric slopes.

Conclusions:

• Endogenous attention mitigates the size-eccentricity effect, suggesting it counteracts cortical magnification.
• Attentional rescaling enhances peripheral size accuracy and discriminability.
• Misdirected attention exacerbates peripheral underestimation, similar to optic ataxia biases.