The Production Effect: Delineation of a Phenomenon Colin M. MacLeod, Nigel Gopie, Kathleen L. Hourihan, Karen R. Neary, and Jason D. Ozubko University of Waterloo In 8 recognition experiments, we investigated the production effect—the fact that producing a word aloud during study, relative to simply reading a word silently, improves explicit memory. Experiments 1, 2, and 3 showed the effect to be restricted to within-subject, mixed-list designs in which some individual words are spoken aloud at study. Because the effect was not evident when the same repeated manual or vocal overt response was made to some words (Experiment 4), producing a subset of studied words appears to provide additional unique and discriminative information for those words—they become distinctive. This interpretation is supported by observing a production effect in Experiment 5, in which some words were mouthed (i.e., articulated without speaking); in Experiment 6, in which the materials were pronounceable nonwords; and even in Experiment 7, in which the already robust generation effect was incremented by production. Experiment 8 incorporated a semantic judgment and showed that the production effect was not due to “lazy reading” of the words studied silently. The distinctiveness that accrues to the records of produced items at the time of study is useful at the time of test for discriminating these produced items from other items. The production effect represents a simple but quite powerful mechanism for improving memory for selected information. Keywords: memory, encoding, production, generation, distinctiveness In 1978 Slamecka and Graf reported a thorough set of experi- ments demonstrating that producing a word from a cue (e.g., producing fast from the cue rapid-f) leads to considerably better memory for that word than does simply reading the word. The phenomenon that they called the “generation effect” has subse- quently become one of the most widely used manipulations in memory research, leading to their article becoming a citation classic (see Slamecka, 1992), now having been cited more than 500 times and having spawned hundreds of directly related articles (for a meta-analysis, see Bertsch, Pesta, Wiscott, & McDaniel, 2007). The generation effect is a member of a very select club: manip- ulations that have consistent, reliable effects on retention of a stimulus that was presented only once. Other such manipulations include imagery (Paivio, 1971) and elaboration (Craik & Lockhart, 1972). All three of these involve some recoding of the stimulus, and all produce quite substantial memory benefits, often an im- provement of 10% or even more relative to a “standard” baseline of simply reading the word. Enriching the encoding of the stimulus definitely enhances memory for it, in line with what we know generally about mnemonic techniques (see Higbee, 1988). Improving Memory by Saying a Word Aloud In the same period, another factor was first reported to benefit memory but, unlike the others, it failed to attract subsequent research attention. In the study in question, Hopkins and Edwards (1972) tested a key assumption of frequency theory (Ekstrand, Wallace, & Underwood, 1966)—that recognition should be better for pronounced than for unpronounced words because pronuncia- tion would increment the item’s frequency (see Hopkins, Boylan, & Lincoln, 1972, for evidence that pronunciation does increase judged frequency). To test this prediction, Hopkins and Edwards used two recognition tests: two-alternative forced choice (Exper- iment 1) and yes/no (Experiment 2). In both experiments, three groups of subjects studied 100-word lists. There were two pure-list groups— one read all 100 words aloud, and one read all 100 words silently—and one mixed-list group, which read 50 of the words aloud and 50 silently. In comparing the two pure-list conditions, Hopkins and Edwards (1972) found no between-subjects benefit to reading words aloud. But in the mixed-list condition, words read aloud were better recognized than those read silently. This pattern held for both types of recognition test, with the within-subject benefit of reading aloud being approximately 10%. Hopkins and Edwards suggested that the effect was at encoding. Colin M. MacLeod, Nigel Gopie, Kathleen L. Hourihan, Karen R. Neary, and Jason D. Ozubko, University of Waterloo, Waterloo, Canada. Nigel Gopie is now at the Rotman Research Institute, Toronto, Canada. Kathleen L. Hourihan is now at the University of Illinois at Urbana- Champaign. This research was supported by Natural Sciences and Engineering Research Council of Canada Discovery Grant A7459. This article is dedicated to the memory of Norman J. Slamecka, longtime colleague of Colin M. MacLeod at the University of Toronto. In tribute, the title of this article is a (slight) variation on that of the original article on the generation effect (Slamecka & Graf, 1978); we thank Peter Graf for his permission. We thank Keehan Bailey, Emily Bryntwick, Samantha Chaves, Domenica De Pasquale, Nicole Deckert, Grace Hsiao, Jingjing Ji, Marita Partanen, and Molly Pottruff for assistance with collecting the data and Amy Criss, Neil Mulligan, and Hubert Zimmer for their advice concerning the original version of this article. Correspondence concerning this article should be addressed to Colin M. MacLeod, Department of Psychology, University of Waterloo, 200 Uni- versity Avenue West, Waterloo, Ontario N2L 3G1, Canada. E-mail: cmacleod@uwaterloo.ca Journal of Experimental Psychology: © 2010 American Psychological Association Learning, Memory, and Cognition 2010, Vol. 36, No. 3, 671– 685 0278-7393/10/$12.00 DOI: 10.1037/a0018785 671