This paper examines the ability of a dual-system, formal modelof categorization COVIS (Ashby, Paul & Maddox, 2011) topredict the learning performance of participants on the six cat-egory structures described in Shepard, Hovland and Jenkin’s(1961) seminal study. COVIS assumes that category learningis mediated by two dissociable neural systems that compete tocontrol responding. The verbal system explicitly tests verbal-izable rules, whereas the implicit system gradually associateseach stimulus with the appropriate response. Although COVISis highly influential, there are no published evaluations of theformal model against classic category learning data (COVIS ismost typically applied heuristically to the design of new exper-iments). In the current paper, we begin to address this gap inthe literature. Specifically, we demonstrate that COVIS is ableto accommodate the ordinal pattern found by Shepard et al.,provided that adjustments consistent with the model’s theoret-ical framework are made.

Some argue that category learning is mediated by two com-peting learning systems: one explicit, one implicit (Ashby etal., 1998). These systems are hypothesised to be responsi-ble for learning rule-based and information-integration cate-gory structures respectively. However, little experimental workhas directly investigated whether people are conscious of cat-egory knowledge supposedly learned by the implicit system.Here we report one experiment that directly compared explicitrecognition memory for exemplars between these two categorystructures. Contrary to the predictions of the dual-systems ap-proach, we found preliminary evidence of superior exemplarmemory after information-integration category learning com-pared to rule-based learning. This result is consistent with thehypothesis that participants learn information-integration cate-gory structures by using complex rules.