Why interleaving enhances inductive learning: The roles of discrimination and retrieval

Abstract

Kornell and Bjork (Psychological Science 19:585-592, 2008) found that interleaving exemplars of different categories enhanced inductive learning of the concepts based on those exemplars. They hypothesized that the benefit of mixing exemplars from different categories is that doing so highlights differences between the categories. Kang and Pashler (Applied Cognitive Psychology 26:97-103, 2012) obtained results consistent with this discriminative-contrast hypothesis: Interleaving enhanced inductive learning, but temporal spacing, which does not highlight category differences, did not. We further tested the discriminative-contrast hypothesis by examining the effects of interleaving and spacing, as well as their combined effects. In three experiments, using photographs of butterflies and birds as the stimuli, temporal spacing was harmful when it interrupted the juxtaposition of interleaved categories, even when total spacing was held constant, supporting the discriminative-contrast hypothesis. Temporal spacing also had value, however, when it did not interrupt discrimination processing.Keywords Categorization . Induction . Interleaving . Spacing . MetacognitionPeople accumulate a great deal of knowledge via inductive learning. Children, for example, learn concepts such as boat or fruit by being exposed to exemplars of those categories and inducing the commonalities that define the concepts.Later in life, we might learn to distinguish between different species of butterflies or birds, as in the present research. Such inductive learning is critical in making sense of events, objects, and actions-and, more generally, in structuring and understanding our world. In the present research, we examined how exemplars of to-be-learned categories should be sequenced and spaced in order to optimize inductive learning. Kornell and Bjork (2008) investigated the effect of study schedules on inductive learning-specifically, learning artists' painting styles from exemplars of their paintings. Images of six paintings by each of 12 artists were presented for study, with the artist's name displayed below each painting. The paintings by half of the artists were blocked (i.e., all six paintings by a given artist were shown consecutively), whereas the paintings by the other six artists were interleaved (i.e., mixed together). After the learning phase, participants were shown new paintings by each of the 12 artists and were asked to identify which artist had painted each new painting. Kornell and Bjork found that interleaving artists' paintings led to better performance on this inductive task than did blocking-even though participants consistently believed that blocking, rather than interleaving, had been more helpful for learning the artists' styles.

Improving encoding strategies as a function of test knowledge and experience

“…It is possible, for example, that although participants in the readadvantage condition failed to exhibit a generation effect, they may have still subjectively perceived themselves as performing better on generate items than on read items. (Such an illusion would be similar to that observed in studies comparing the effects of interleaving schedules versus blocked schedules in the learning of related skills or concepts, which have shown that participants, even after performing better following interleaved practice tend to believe that they learned better under blocked practice, e.g., Birnbaum, Kornell, Bjork, & Bjork, 2013;Kornell & Bjork, 2008;Simon & Bjork, 2001).…”

Blocking as a friend of induction in verbal category learning

“…Rather, the interleaving of exemplarsand the enhanced discriminative contrast afforded by that presentation-was key to better learning. Additional support was found for this discriminative-contrast hypothesis in experiments conducted by Birnbaum, Kornell, Bjork, and Bjork (2013) using pictorial representations of birds and butterflies. On the whole, these findings represent a serious challenge to the assumption that interleaving impedes the induction of novel concepts from exemplars.…”

“…Examples of this type of categorization include the decision rules employed by wine tasters, or Bthose used by artists to categorize unfamiliar paintings according to the Renaissance master who created them^ (Ashby et al, 1998, p. 442). This last example describes a categorization task similar to that used in the research by Kornell and Bjork (2008) and others (Birnbaum et al, 2013;Kang & Pashler, 2012;Kornell et al, 2010;Wahlheim, Dunlosky, & Jacoby, 2011;Zulkiply & Burt, 2013). In these studies, an interleaved format was found to be a more effective than a blocked format, suggesting a possible interaction between categorization type and practice schedule.…”

“…These researchers found an overwhelming preference for selecting additional birds from a given family (blocked study) over mixing birds from different families (interleaved study), although there was ultimately no error difference by formats. However, as others have found in studies involving both verbal-and motor-skill learning (e.g., Birnbaum et al, 2013;D. A. Simon & Bjork, 2001;Zechmeister & Shaughnessy, 1980), interleaved study conditions typically result in better learning, even as participants' subjective judgments suggest the opposite.…”

“…Other research had required participants to guess at category memberships during initial learning and to generate one of three categories unaided during testing and transfer (Carvalho & Goldstone, 2014a, 2014b. Still others had directly paired stimuli and category memberships during learning, then had used as many as 13 forced choice alternatives during testing (e.g., Birnbaum et al, 2013;Kornell & Bjork, 2008;Zulkiply & Burt, 2013;Zulkiply et al, 2012). The reduced complexity of recognition demanded by our task may have led to relatively superficial learning and performance.…”