Behavioral results in Experiment 2. A reflects the development of participants’ expected numbers for high- and low-number shapes throughout the block. Their expected number difference between the high- and low-number shapes increased gradually. (B) shows an approximately normal distribution of PEs. (C) describes the significant correlations between the adjustment size of prediction (prediction_N − prediction_N − 1) and the PE of trial N − 1 for high- and low-number shapes. The scatterplots show across-subjects correlations. The error bar denotes standard errors. * denotes P < 0.05, and *** denotes P < 0.001.