MOST DIRECTED FORGETTING IN PIGEONS CAN BE ATTRIBUTED TO THE ABSENCE OF REINFORCEMENT ON FORGET TRIALS DURING TRAINING OR TO OTHER PROCEDURAL ARTIFACTS

In research on directed forgetting in pigeons using delayed matching p rocedures, remember cues, presented in the delay interval between samp le and comparisons, have been followed by comparisons (i.e., a memory test), whereas forget cues have been followed by one of a number of di fferent sample-independent events. The source of directed forgetting i n delayed matching to sample in pigeons was examined in a 2 x 2 design by independently manipulating whether or not forget-cue trials in tra ining ended with reinforcement and whether or not forget-cue trials in training included a simultaneous discrimination (involving stimuli ot her than those used in the matching task). Results were consistent wit h the hypothesis that reinforced responding following forget cues is s ufficient to eliminate performance deficits on forget-cue probe trials . Only when reinforcement was omitted on forget-cue trials in training (whether a discrimination was required or not) was there a decrement in accuracy on forget-cue probe trials. When reinforcement is present, however, the pattern of responding established during and following a forget cue in training may also play a role in the directed forgettin g effect. These findings support the view that much of the evidence fo r directed forgetting using matching procedures may result from motiva tional and behavioral artifacts rather than the loss of memory.