title: Limitations to the spacing effect: demonstration of an inverted u-shaped relationship between interrepetition spacing and free recall.
abstract: The spacing effect refers to the finding that memory for repeated items improves when the interrepetition interval increases. To explain the spacing effect in free-recall tasks, a two-factor model has been put forward that combines mechanisms of contextual variability and study-phase retrieval (e.g., Raaijmakers, 2003; Verkoeijen, Rikers, & Schmidt, 2004). An important, yet untested, implication of this model is that free recall of repetitions should follow an inverted u-shaped relationship with interrepetition spacing. To demonstrate the suggested relationship an experiment was conducted. Participants studied a word list, consisting of items repeated at different interrepetition intervals, either under incidental or under intentional learn instructions. Subsequently, participants received a free-recall test. The results revealed an inverted u-shaped relationship between free recall and interrepetition spacing in both the incidental-learning condition and the intentional-learning condition. Moreover, for intentionally learned repetitions, the maximum free-recall performance was located at a longer interrepetition interval than for incidentally learned repetitions. These findings are interpreted in terms of the two-factor model of spacing effects in free-recall tasks.
authors.affiliation: Department of Psychology, Erasmus University Rotterdam, The Netherlands. verkoeijen@fsw.eur.nl
authors.forename: Peter P J L
authors.initials: PP
authors.lastname: Verkoeijen
authors.forename: Remy M J P
authors.initials: RM
authors.lastname: Rikers
authors.forename: Henk G
authors.initials: HG
authors.lastname: Schmidt
mesh_terms: D006801:Humans; D033182:Intention; D007858:Learning; D011939:Mental Recall; D013028:Space Perception; D013997:Time Factors