GUESSING STRATEGIES, AGING, AND BIAS EFFECTS IN PERCEPTUAL IDENTIFICATION

In the typical single-stimulus perceptual identification task, accurac y is improved by prior study of test words, a repetition priming benef it. There is also a cost, inasmuch as previously studied words are lik ely to be produced (incorrectly) as responses if the test word is orth ographically similar but not identical to a studied word. In two-alter native forced-choice perceptual identification, a test word is hashed and followed by two alternatives, one of which is the correct response . When the two alternatives are orthographically similar, test words i dentical to previously studied items are identified more accurately th an new words (a benefit) but tests words orthographically similar to s tudied words are identified less accurately than new words (a cost). R atcliff and McKoon (in press) argue that these are bias effects that a rise in the decision stage of word identification. We report five expe riments that examined the alternative hypothesis that these bias effec ts arise from postperceptual guessing strategies. In single-stimulus p erceptual identification, repetition priming benefits were equally gre at for young and older adults who claimed to use deliberate guessing s trategies and those who did not (Experiment 1). Tn contrast, only grou ps of young and older people who claimed to deliberately guess studied words in a two-alternative forced-choice task (Experiments 2 and 5) s howed reliable benefits and costs. Costs and benefits were abolished i n the two-alternative forced-choice task when a very long study list w as used, presumably because the increased retrieval burden made the us e of deliberate guessing strategies less attractive (Experiment 3). Un der conditions similar to those of Experiment 3, repetition priming wa s observed in single-stimulus perceptual identification (Experiment 4) . These results are consistent with the view that costs and benefits i n the forced-choice perceptual identification task arise from delibera te guessing strategies but that those in the single-stimulus task do n ot. The possibility that the observed relationship between strategy re ports and priming effects reflects erroneous postexperimental assessme nts of strategies by participants is also considered. (C) 1996 Academi c Press.