Fig. 4.

The mean number of collisions made in sessions 1–18. In session 15, unpredictable starting orientations were introduced, along with a 15 s time-out when a collision occurred. This is represented by the dashed black line. Data from sighted participants are shown as solid circles, with error bars representing the standard error of the mean. Data from experts who completed only a single session are shown as open squares. For comparison, they have been plotted at session 14 (i.e. after sighted participants have had 13 sessions of practice with the task that experts did in a single session without training).