Apomorphine locomotor sensitization can be potentiated by environmental change: Evidence for a non-Pavlovian associative behavioral contrast factor in sensitization expression

► Environmental context is a determinant of the expression of sensitization. ► Contrast effects can be applied to the expression of apomorphine sensitization. ► The change from square to round arena potentiated sensitization. ► The change in the reverse direction, from round to square attenuated sensitization. ► High activity arenas are analogous to high reward schedules and vice versa.