Example psychometric curves from a typical subject. (A) Initial training with full contrast, 0.05cpd, 2Hz gratings. After the initial training period, performance was measured with varying spatial frequency (B), contrast (C), temporal frequency (D) and orientation of grating (E). All data show binomial fits to the data with 95% confidence intervals. In B,C,D and E the condition corresponding to the original training is denoted by.'*'