Do McCollough effects provide evidence for global pattern processing?

Area of Science:

• Visual perception
• Color vision
• Psychophysics

Background:

• Contingent color aftereffects (CAEs), also known as McCollough effects, demonstrate how prolonged exposure to specific color-pattern pairings can alter subsequent color perception.
• Previous research has explored the independence of CAEs induced by different patterns, with some studies suggesting independence based on composite stimuli.

Purpose of the Study:

• To investigate whether contingent color aftereffects (CAEs) induced by orthogonally related patterns (horizontal/vertical and concentric/radial) are independent.
• To determine if global or local features of visual patterns primarily control the characteristics of these aftereffects.

Main Methods:

• Inducing CAEs using two pairs of orthogonally related visual patterns: horizontal/vertical and concentric/radial.
• Employing composite test patterns to assess aftereffect independence, similar to methods used by Emerson, Humphrey, & Dodwell (1985).
• Utilizing unitary patterns and isolating specific regions to examine interactions between induced aftereffects.

Main Results:

• Initial tests with composite patterns suggested independent CAEs.
• However, tests with unitary patterns revealed additive or competing effects when line orientations were similar.
• Analysis of isolated regions demonstrated clear interactions between the aftereffects of different patterns.

Conclusions:

• The findings do not support the hypothesis that global features of visual patterns exclusively control CAEs.
• Interactions observed in specific regions indicate that local features play a significant role in the manifestation and interaction of CAEs.
• The independence of CAEs induced by different pattern types is questionable, particularly in areas of stimulus overlap.