Normalized pupil diameter as a function of time.

<p>(A) Each function represents the averaged pupil diameter of 12 subjects during the conduction of the visual conjunction search task. The data in each trial was normalized relative to the pupil size during the cross fixation period immediately preceding the trial. Different functions denote the different training day: 1^st, 3^rd, 5^th, and 10^th day, respectively. (B) Each function represents the averaged pupil diameter of 12 subjects conducting the passive viewing task. In passive condition subjects observed the visual search display, but no task was imposed. The data in each trial was normalized relative to the pupil size during the cross fixation period immediately preceding the trial. Different functions denote the different experimental day: 1^st, 3^rd, 5^th, and 10^th day, respectively.