Rewarding objects appear larger but not brighter.

Area of Science:

• Cognitive Psychology
• Neuroscience
• Visual Perception

Background:

• The relationship between reward and visual perception is a debated topic.
• Previous research has yielded conflicting results on whether reward affects perceived object size.

Purpose of the Study:

• To investigate the influence of reward magnitude on the perceived size and brightness of visual objects.
• To clarify the long-standing controversy regarding reward's effect on visual perception.

Main Methods:

• A novel two-alternative forced-choice paradigm was employed, incorporating an asymmetric reward schedule and task reversal.
• Participants (n=27) performed tasks involving choosing larger/smaller or brighter/darker objects under differing reward conditions.
• Response biases were analyzed to determine the impact of reward on perceived size and luminance.

Main Results:

• Significant response biases toward the more rewarding object were observed in size perception tasks, differing between reversed conditions.
• Perceived luminance, however, showed similar response biases across reversed tasks, indicating immunity to reward manipulation.
• These findings demonstrate that reward selectively influences perceived size but not brightness.

Conclusions:

• Reward association with visual objects can lead to an overestimation of their size.
• Perceived object brightness is not significantly altered by reward magnitude.
• This study provides evidence for a specific mechanism by which reward modulates visual perception.