The effect of prediction error on overt attention and learning in humans

It has been suggested that attention modulates the speed at which cues come to predict contingent outcomes, and that attention changes with the prediction errors generated by cues. Evidence for this interaction in humans is inconsistent, with divergent findings depending on whether attention was measured with eye fixations or learning speed. We included both measures in our experiment. Initially, predictive cues (A and B) were consistently followed by one outcome (o1), while nonpredictive cues (X and Y) were followed by two randomly alternating outcomes (o1 and o2). Consistent with an effect of prediction error, participants' fixated for longer on the nonpredictive cues than on the predictive ones. Then, the cues were combined in three pairs: AX, followed by o1, and AY and BX, followed by o2. Discrimination of AX and AY depended on the previously nonpredictive cues and, given that these received more attention during initial training, it should proceed faster than discrimination of AX and BX, which depended on the previously predictive cues. However, participants learned to predict the outcomes of AY and BX at a similar rate. The fixation times were similar for the previously predictive and previously nonpredictive cues. We discuss reasons that could explain these findings.