Correlates of Perceptual Orientation Biases in Human Primary Visual Cortex.

Area of Science:

• Neuroscience
• Cognitive Science
• Vision Science

Background:

• Human perception relies on probabilistic inference, integrating sensory data with prior knowledge.
• Prior knowledge influences perception more strongly when sensory evidence is less certain.

Purpose of the Study:

• To investigate how manipulating stimulus certainty affects behavioral judgments and neural responses in orientation processing.
• To explore the interaction between prior expectations and sensory evidence in visual perception.

Main Methods:

• Participants judged stimulus orientation under varying certainty conditions (bandwidth, contrast, duration).
• Event-related fMRI BOLD responses in primary visual cortex (V1) were measured.
• A multivariate classifier analyzed V1 activity patterns for orientation classification.

Main Results:

• Behaviorally, participants showed a bias towards reporting orientations as oblique (45°) under high certainty, which decreased with reduced certainty.
• V1 activity patterns, when classified, mirrored perceptual biases, showing an oblique bias at high contrast and a wider cardinal range at low contrast.
• These orientation biases are not solely explained by a cardinal orientation prior.

Conclusions:

• Prior expectations significantly bias visual perception and neural processing, even at early cortical stages like V1.
• The findings demonstrate a parallel between perceptual biases and neural activity patterns in V1 concerning orientation processing.
• Visual perception is an active process of inference, shaped by both incoming sensory data and internal priors.