Differential runway performance using goal box placement and running trials as discriminative stimuli

Two experiments compared the effects of reinforced, partially reinforced and nonreinforced intertrial goal box placements (ITR, ITP, and ITN respectively) on runway performance. In Experiment I differential responding (animals running slower on nonreinforced (N) trials than on reinforced (R) trials) was observed during acquisition for subjects receiving ITP preceding N trials or subjects receiving ITP before R trials, and also for subjects receiving ITR preceding N trials. No differential responding was observed in subjects receiving ITP prior to both N and R trials or ITN prior to N trials. In extinction, the subjects which had responded differentially during acquisition demonstrated reduced resistance to extinction in comparison to the subjects which had not. In Experiment II, a 2 × 2 factorial design was utilized with placement schedule (ITN and ITP) and type of trial predicted by placement (N and R) serving as the factors. Differential responding was observed in all four groups. The apparent contradiction between the results and the discrimination hypothesis proposed by Capaldi and Olivier (1967) to explain the attenuation of ITR and ITN effects on resistance to extinction is discussed.