Behavioural results, expressed as difference between probe trials and preceding reinforced trials.

Results are shown both for the mean across all five probe blocks (left) and separately for each probe block. Points reflect individual participants’ behaviour. (A) The sensitivity index d’ increased in probe compared to reinforced trials. (B) The negative bias criterion c decreased on probe blocks, indicating a reduced propensity to act on probe trials. (C), (D) Both hit rate (HR, C) and false alarm rate (FAR, D) decreased on probe blocks, but the decrease in FAR was more pronounced than the decrease in HR, which lead to the increase in d’ represented in (A).