Attention Reverses the Effect of Prediction in Silencing Sensory Signals

Predictive coding models of perception suggest that predicted sensory signals are attenuated (silencing of prediction error). These models, though influential, are challenged by the fact that prediction sometimes enhances, rather than reduces task-relevant sensory signals, as in the case of spatial cueing experiments. One possible explanation is that in these experiments, prediction (i.e. whether a stimulus is likely to be presented) is confounded with attention (i.e. whether a stimulus requires a behavioural response), which is known to boost rather than reduce sensory signal. However, recent theoretical work on predictive coding inspires an alternative hypothesis, and suggests that attention and prediction may operate synergistically to improve the precision of perceptual inference. This model posits that attention leads to heightened weighting of sensory evidence, thereby reversing the sensory silencing by prediction. We factorially manipulated attention and prediction in an fMRI study to test the validity of this model. Our results support a predictive coding model wherein attention reverses the sensory attenuation of predicted signals. This may explain the seemingly contradictory findings in the literature regarding the effects of prediction on neural responses.