The generation effect or simply generating an effect?

The Generation Effect is the phenomenon wherein attempting to retrieve or generate information from memory leads to better encoding and retention than passive rehearsal. Kornell and Terrace were the first to provide evidence for the Generation Effect in nonhuman animals, demonstrating that two rhesus monkeys performed markedly worse when tested following a passive learning condition relative to an active learning condition. In Experiment 1, using the same paradigm as Kornell and Terrace, we demonstrate that pigeons also display this effect. However, an assumption underlying the Generation Effect is that, under passive learning conditions, subjects will still display some evidence of learning but less than that displayed in active learning conditions. In Experiment 2, we examined this issue by pretraining pigeons on a list with hints and then comparing their acquisition of that same list to animals that did not receive any pretraining. Again, we found no evidence that pretraining on a list with hints conferred any advantage when learning that list without hints, a manipulation that Kornell and Terrace did not undertake. In summary, our data raise doubts about the evidence for the Generation Effect in nonhuman animals.