Not what you expect: experience but not expectancy predicts conditioned responses in human visual and supplementary cortex.

When paired with aversive events, visual conditioned stimuli (CS) provoke increased activations in visual cortex. It is unclear however whether these changes reflect cognitive processes such as expectancy of the aversive unconditioned stimulus (US), or implicit associative learning of the contingencies outside awareness. Here, we used the "gambler's fallacy" phenomenon to parametrically and inversely manipulate the expectancy of an US and the number of conditioning trials: Increasing the number of CS-US pairings was associated with participants expecting the US to be less likely and vice versa. Magnetocortical activity evoked by the CS in occipital and supplementary motor areas was linearly related to the associative strength (number of CS-US pairings), but decreased as a function of expectancy. These results suggest that the cortical facilitation of fear cue processing is determined by associative strength and previous exposure to learning contingencies rather than by the cognitive anticipation for the US.