Figure 4.

Response enhancement in the context-modulated phase measured as delta-surprisals. A, Cumulative frequency distributions of delta-surprisals obtained for single units in Experiment 1. The cumulative frequency for each x value as a percentage of the total is shown on the y-axis as a function of delta-surprisal values on the x-axis. Delta-surprisals for the canary (red), silence (blue), and ZF (black) context conditions are plotted. The box plot (right) shows the minimum (the bottom of the whisker), first quartile (the bottom of the box), median (the red line in the middle of the box), third quartile (the top of the box), and maximum (the top of the whisker) and possible outliers (red cross) of delta-surprisals in the ZF context condition (ZF, left box), the silence context condition (silence, middle box), and the canary context condition (Can, right box). B, Cumulative frequency distributions (left) and box plot (right) of delta-surprisals obtained for multiunits in the three conditions of Experiment 1. Multiunit data showed the same pattern of results as single-unit data. C, Cumulative frequency distributions (left) and box plot (right) of adaptation indices for the three conditions tested in Experiment 1. Adaptation indices were not different from each other in the three conditions. D, Scatter plot of absolute values of D′ and delta-surprisals. The black dashed line is a flat reference line (slope zero). Red dashed line shows the best-fitting line from a linear regression, which shows no significant correlation between the two variables (Spearman's r = 0.056, p > 0.557). E, Cumulative frequency distributions (left) and box plot (right) of slopes of linear regression between trial number and trial-by-trial delta-surprisals in the three conditions of Experiment 1. In the canary and silence context conditions, there was no significant change in delta-surprisals over trials. In contrast, delta-surprisals increased significantly with trials in the ZF context condition.