Contrast-dependent red-green balance shifts depend on S-cone activity

Area of Science:

• Visual Perception
• Color Science
• Neuroscience

Background:

• Previous studies demonstrated contrast-dependent red-green hue shifts in yellow and brown targets.
• Surround luminance influences perceived target hue, causing shifts from greenish-brown to reddish-yellow and vice versa.

Purpose of the Study:

• To investigate the generality of red-green hue shifts across different target colors (yellow/brown, achromatic, blue).
• To explore the underlying neural processes and cone pathway contributions to these contrast-dependent hue shifts.

Main Methods:

• Presented various target stimuli (yellow/brown, achromatic, blue) against different surround luminances.
• Measured red-green hue shifts and analyzed the role of S-cone, L-cone, and M-cone (M-cone) excitations.
• Investigated the necessity of monocular presentation for the hue shift phenomenon.

Main Results:

• Red-green hue shifts were largest for yellow/brown targets, decreasing for achromatic and blue targets with increased S-cone excitation.
• The magnitude of the hue shift correlated with the target's S/(L+M) cone excitation under bright white surrounds.
• The hue shift requires simultaneous presentation to the same eye, indicating monocular processing.

Conclusions:

• Contrast-dependent red-green hue shifts are influenced by target color and S-cone excitation.
• S-cone signals from bright surrounds may contribute to hue shifts, but the precise mechanism for target-specific variations remains unclear.
• Findings support the role of monocular pathways in mediating these perceptual effects.