Interleaved Presentation Benefits Science Category Learning

The present study investigated whether the sequencing of exemplars affects learning of rule-based science categories. We taught undergraduate students chemical categories by showing them diagrams of organic chemical compounds accompanied by their category label in either an interleaved or blocked fashion. On a categorization test of novel exemplars administered 2 days later, interleaved presentation produced superior performance than blocked presentation for categories that were visually simple (Experiment 1) and relatively more complex (Experiment 2). The advantage of interleaved presentation was still observed when the diagnostic features of each category were highlighted during study (Experiments 3 and 4), suggesting that the benefit of interleaving may not be due solely to increasing the salience of contrastive features that differentiate the categories. These findings demonstrate that interleaved presentation can improve learning of educationally relevant categories, even when coupled with pedagogical techniques that emphasize the diagnostic features of each category. General Audience Summary When learning multiple categories by viewing members of the categories, the order in which these examples are presented has been shown to influence learning. For instance, if you were trying to learn to identify and differentiate hawks and falcons, presenting examples of each category in an interleaved sequence during training (HFHFHF) would likely improve your ability to correctly categorize hawks and falcons, relative to a blocked training sequence (HHHFFF). We investigated whether this apparent benefit of interleaved presentation extended to the learning of educationally relevant scientific categories (i.e., organic chemicals), and also whether the following factors played a role: (a) the level of similarity among the examples and (b) highlighting of the diagnostic features of each category during training. Across four experiments, we found that interleaved presentation benefitted learning of the chemical categories, with simple as well as more complex categories. Neither the level of similarity among the examples nor highlighting the diagnostic features of a category influenced the interleaving advantage, although highlighting the diagnostic features did improve learning overall. These findings suggest that students may benefit from the interleaving of different categories during science instruction, even when the teacher (or the textbook) explicitly points out the diagnostic features of each category to help learning.