Illustration of changes in the psychometric function over the course of training.

<p>Plots show the psychometric functions obtained from three sessions of roving training, namely from the first (dotted line), middle (dashed line), and last sessions (solid line), as well as during the final session of non-roving training (yellow line). <i>P_reporthigher</i> was plotted against the test contrast, and data were fitted using a Weibull function. Lines represent the fitted curve. Left column: monkey 1; right column: monkey 2. A & B: 20% sample (red); C & D: 30% sample (green); E & F: 40% sample (blue). Improvement in the psychometric function is represented by a shift in the PSE (vertical line) towards the respective sample contrasts; such a shift is clearly visible for the 40% sample condition in monkey 1, and the 20% sample condition in monkey 2.