Because there have been only four aquariums, 4 fish were studied at a given time. The following techniques were common to all four experiments: There was no explicit education of the response. Immediately before each consultation, the frame was emplaced and the lights were illuminated behind the a method mirror. The mirror then was uncovered and the session began. During each consultation, reinforcement consisted of a 10 s period by which the lights behind the mirror were extinguished, making the mirror reflective. A 10 s period of mirror access was certain based on Wirth et al.