Prior probability cues bias sensory encoding with increasing task exposure.

Area of Science:

• Cognitive Neuroscience
• Computational Neuroscience
• Human Perception

Background:

• Prior knowledge influences perceptual decision-making, causing biases in reaction time and accuracy.
• Traditional models attribute these biases to strategic criterion adjustments, like starting point shifts.
• Emerging evidence suggests expectations may also directly bias sensory evidence encoding.

Purpose of the Study:

• To investigate whether probabilistic cues modulate sensory evidence encoding beyond strategic criterion adjustments.
• To differentiate neural correlates of criterion adjustments from sensory encoding biases.
• To examine the temporal dynamics of these effects with task exposure.

Main Methods:

• Electroencephalography (EEG) recording during a contrast discrimination task.
• Use of valid, invalid, and neutral probabilistic cues.
• Measurement of sensory evidence encoding via steady-state visual-evoked potentials (SSVEP).
• Assessment of criterion adjustments via motor cortex mu-beta band activity.

Main Results:

• Probabilistic cues induced significant motor preparation biases, consistent with criterion adjustments.
• Cues also modulated SSVEP, indicating a bias in sensory evidence encoding.
• Criterion adjustments appeared early, while sensory encoding effects emerged with extended task exposure.

Conclusions:

• Probabilistic information influences perceptual decisions through both strategic criterion adjustments and direct modulation of sensory evidence encoding.
• Sensory encoding biases emerge with learning and task experience.
• Findings challenge purely strategic accounts and highlight the dual role of expectations in perception.