“…In order to familiarize subjects with the learning conditions and reduce both the number of pseudo avoidance responses and the inverted relation that exists between shock intensity and performance because of fear(Dieter, 1977; D. McAllister & McAllister, 1979; W. McAllister, McAllister, Dieter, & James, 1979), every animal was given three shuttle box adaptation sessions, one per day, each consisting of 20 min of free ambulation in the shuttle box (Campden Instruments).…”