FIGURE 1. Experimental approach and results of experiment 1.

a, Colour recall task. b, Mixture model of performance, showing the probability of reporting each colour value given a sample colour at 180°. When the probed item is present in memory, the reported colour tends to be near the original colour (blue broken line). When the probed item is not present in memory, the observer is equally likely to report any colour value (red broken line). When collapsed across trials, the data comprise a mixture of these two trial types (solid line), weighted by the probability that the probed item was stored in memory. c, Results of experiment 1 (N = 8). P_m and s.d. are defined in the text.