Fig 6. Expectation, attention, MSPC, and predictive coding.

Results presented in this study can be accounted for by the predictive coding framework of perception as follows: 1) Expectation (the probability for the appearance of specific stimuli) relates to descending prediction signals. 2) Better predictions (as afforded by the PV trials in Experiment 1) increases the efficiency of top-down and bottom-up signal integration at low-level visual areas, as reflected by the increased MSPCstim with expectation (Figs 2 and 4). 3) Attention reflects a (precision-weighted) control mechanism for the propagation of prediction error signals. 4) Attention effectively increases the influence of prediction error signals on expectations at higher hierarchical levels, as reflected by the increased MSPCres with attention (Figs 3 and 4). 5) The effect of expectation on the integration of top-down and bottom-up information at lower visual areas is less dependent on attention than the integration at higher levels. Hence, while MSPCstim increased with expectation for both attended and unattended stimuli (Fig 5), the influence of expectation on MSPCres was attention dependent (Fig 5). MSPCres, multispectral phase coherency (response); MSPCstim, MSPC (stimulus); PV, pattern violation.