Interpreting pre-stimulus alpha effects on visual detection: sensitivity vs bias

Determine whether weak pre-stimulus alpha power reflects enhanced visual sensitivity to targets or instead produces a liberal decision bias to report target presence in visual detection tasks.

Background

Pre-stimulus alpha power is linked to cortical excitability and visual detection performance. Prior findings suggest both impeded detection with strong alpha and altered subjective visibility or confidence with weak alpha, raising ambiguity about whether the effect reflects true sensory gains or decision-level biases.

Resolving this ambiguity is critical for theories connecting alpha oscillations to perceptual processing and conscious access.