Differentiating the Contextual Interference Effect from the Spacing Effect

1. Differentiating the Contextual Interference Effect from the Spacing Effect Lindsey E. Richland, Jason R. Finley, Robert A. Bjork University of California, Los Angeles Abstract Interleaved as opposed to blocked presentation of similar stimuli sets can impair test performance during training, but enhance retention and generalization of learning at a delay (Dempster,1990, Shea & Morgan, 1979). Battig (1972) defined this as the Contextual Interference Effect. The contextual interference effect has been replicated in motor skills and word-learning domains; however, there has been a natural confound with the spacing effect. Interleaving introduces spacing not typically present in blocked orders. The current study used foreign language word pairs to distinguish between the spacing and contextual interference effects. English words were paired with their translation into Swahili and into Estonian (materials from Pashler, UCSD). The primary findings reveal: 1. Multiple translations for a single English word produce contextual interference during learning. 2. Interleaving produced benefits on a final test above and beyond the spacing effect. Methods Participants 80 Undergraduates at UCLA participated for course credit. Stimuli Subjects were trained to generate the Swahili and Estonian translations for 16 English words using anticipation trials. Each word was presented on six trials, with feedback on every trial regardless of performance. Manipulations: 1. Language of the intervening items between repetitions of a word. a. Interleaved: Estonian and Swahili words were interspersed. b. Blocked: Estonian and Swahili words were separated. 2. Spacing between repetitions of a single word. a. Same-spacing: a mean of 6 words between repetitions. b. Double-spacing: a mean of 12 words between repetitions. (NOTE: double-spacing was only used for words in the interleaved condition) Training Screens: TEST: On a final test, which occurred immediately after training, participants were asked to provide the translation of every English word into both Estonian and Swahili : Results Interleaving and Spacing effects were analyzed on learning curves and Posttest performance. Figure 1. Performance during training and on a post test, by presentation order and spacing. Figure 2. Intrusions of same word, incorrect language during 2nd half of training. In the interleaved condition, participants showed the slowest learning curves (see Figure 1) and made the most errors during training (see Figure 2). However, this performance interacted with a change in task demands and the opposite was found on the posttest, with the highest mean scores for interleaved double-spaced materials. In the interleaved condition, double-spacing slowed learning during training but resulted in higher performance than same-spacing on the posttest. Predictions 1. Translations for the same word into different languages will produce contextual interference. 2. Interleaving materials will result in higher retention than blocked presentation, even when spacing is held constant across the two conditions, thus demonstrating that the contextual interference effect is distinct from the spacing effect. Summary • Evidence for spacing and interleaving as distinct phenomena. • Contextual Interference induced by two language translations for the same word. • Next steps: 1) increase delay of posttest, 2) add blocked double-spaced manipulation References Battig, W.F. (1972). Intra-task interference as a source of facilitation in transfer and retention. In R.F. Thompson & J.F. Voss (Eds.), Topics in learning and performance (pp. 131-159). New York, NY: Academic Press. Dempster, F. N. (1990). The spacing effect: A case study in the failure to apply the results of psychological research. American Psychologist, 43, 627-634 Shea, J.B., & Morgan, R.L. (1979) Contextual interference effects on the acquisition, retention, and transfer of a motor skill. Journal of Experimental Psychology: Human Learning and Memory, 5, 179-187. Acknowledgements This research was supported by a Cognition and Student Learning Grant from the Institution of Education Sciences (IES) #R305H02 0113 to Robert Bjork & Marcia Linn.