Probabilistic Reward Task

Response bias index reflecting reward sensitivity.

A single horizontal bar appears on each trial, either short or long. Classify it with a keypress: F (left) for short, J (right) for long. Correct responses are usually rewarded and incorrect ones occasionally are — and rewards are deliberately asymmetric, with responses on one side secretly rewarded more often, which can gradually pull your choices toward that side.

Your response bias toward the more-rewarded ambiguous stimulus — a laboratory readout of reward learning developed by Pizzagalli and colleagues. Note one deviation: this version classifies clearly different line lengths (2 vs 8 bars), so stimulus discriminability is much higher than in the original hard-to-distinguish face stimuli; d′ here mainly checks task engagement rather than measuring subtle perceptual discrimination.

Blunted reward learning has been studied in relation to anhedonia and depression in group research; a single online session cannot support that kind of interpretation.