Figure 4. Random dot motion discrimination task and behaviour separated by forepriod (fp) duration.
(A) Task Schematic: Each trial commenced with the presentation of a cloud of moving dots within a circular aperture against a black background. At baseline, the dots were displaced at random from one trial to the next. After an initial foreperiod, the duration of which varied unpredictably from trial-to-trial (800 ms/1200 ms/1600 ms), a portion of the dots, determined separately for each individual subject (M = 7.42%, SD = 2.61%, range = 3–12%), began to move coherently in either a leftward or rightward direction. The schematic depicts a rightward motion trial followed by a leftward motion trial (Note: Arrows are used here to illustrate the direction of motion but were not a feature of the actual stimulus). Feedback was presented at the end of each trial. (B) RT distributions separated by foreperiod duration and response accuracy. Vertical line markers indicate the time of coherent motion onset. (C) Mean RT separated by foreperiod duration and (D) Conditional accuracy functions showing accuracy as a function of RT separated by foreperiod duration. Vertical line markers indicate the time of coherent motion onset. Mean accuracy (E), missed response rate (F), premature response rate (G) and points earned per trial (H), separated by foreperiod. Error bars represent standard error of the mean. Asterisks’ indicate statistical significance of post-hoc comparisons: *=<0.05, **=p < 0.017, ***=p < 0.001; Bonferroni corrected critical p-value=0.017.
Figure 4—figure supplement 1. Choice biases in contrast discrimination task.
