Abstract
Two experiments examined sequential and simultaneous conditioned inhibition in an autoshaping preparation. In Experiment 1, a 5-sec coloured keylight (A) was reinforced when presented alone. However, reinforcement was withheld from trials on which A was preceded by one grid pattern or presented simultaneously with another pattern. A third (control) pattern was presented separately without reinforcement. Inhibition developed most strongly to the grid pattern presented simultaneously with A. However, a transfer test with another excitatory coloured keylight found both inhibitors to be equally strong whether they were tested in simultaneous or in sequential compound. Experiment 2 compared grid patterns that consistently had sequential or simultaneous relations to the excitor with one that was sometimes presented in sequential and sometimes in simultaneous compound. The mixed treatment pattern showed levels of inhibition like the simultaneous or sequential pattern, depending on the temporal relation it bore to A on a particular trial. These results suggest that sequential and simultaneous relations between inhibitors and excitors yield similar amounts of inhibition. However, that inhibition is better exhibited when tested in simultaneous compound with the excitor.