Prior to Block 0, subjects were familiarized with the battery of tasks in a practice block consisting of abbreviated versions of all the tasks except for the subjective perceptions test, which was administered exactly as it would be in Blocks 0, 1 and 2. Except for bathroom breaks, subjects remained seated in the testing booth; they were instructed to bring an activity of their choice to pursue while tests were not being administered. Most subjects brought books or laptops; cellphone use was allowed.
