| The present study examined variables controlling choice between aversive events using pigeons as subjects. Initially, a titration procedure using variable-interval (VI) schedules of food and shock delivery contingent on keypecking was conducted to determine a moderately aversive shock intensity and duration. Subjects were then presented with a choice between food delivery followed by either a single shock or three shocks in a discrete-trials procedure. The change in context affected the aversiveness of the shock. In the VI condition, shock presentation resulted in 40-60% decrease in response rates. In the discrete-trials procedure, however, responding was "all-or-none." Thus, an attempt to redetermine a moderately aversive shock stimulus within the choice context failed. Despite procedural manipulations, no consistent results were obtained such that one shock was selected more often than three shocks. Theoretical issues related to delayed punishment, discrimination, and conditioned reinforcement, as well as future research directions, are discussed. |
