The Production Effect in Implicit Memory: Mixed Evidence from Process Dissociation Procedure, Lexical Decision, Word-Stem Completion, and Category Exemplar Generation Tests

The Production Effect refers to a memory advantage for items learned by reading aloud relative to items learned by silent reading. The effect is commonly attributed to encoding distinctiveness; the act of production makes aloud items distinct from the silent items. Distinctiveness is considered useful only on conscious memory tests but is irrelevant on implicit tests. Indeed, hitherto, the production effect was observed only on explicit tests of memory but not on the implicit test of speeded reading. In the current study, in two experiments, participants learned words by aloud or silent reading and performed different implicit memory tests. In the first experiment, a modified recognition test using the process dissociation procedure was employed, revealing a robust production effect in the inclusion (conscious) but not the exclusion (automatic) condition. In the second experiment, no production effect was found in a simple implicit task (lexical decision) but was documented in two complex implicit tasks (word stem completion and category exemplar generation). These results show that vocal production can enhance some forms of implicit memory. This may result from mechanisms other than distinctiveness contributing to the production effect or the involvement of explicit memory processes (intrusions) in (some) implicit memory tests.