Experiment 1 contingency effect (low minus high contingency) as a function of block for the overtrained stimuli (top) and other stimuli (bottom) with standard errors. The sub-block numbers are indicated on the x-axis, but data are aggregated over the larger mega-blocks for presentation purposes. Light grey indicates the unlearning phase and dark grey indicates the counterconditioning phase. The single squares in the last block represent the low minus new high contingency contrast.