Implicit Learning of an Invariant: Just Say No

Following exposure to 30 four-digit numbers containing an invariant “3”, subjects are found falsely to recognize novel four-digit numbers containing this invariant (positives) in preference to novel numbers that do not contain the invariant (negatives). Despite this false recognition, they are generally unable to report the rule relating test positives to the positives seen during the learning phase. This finding has been taken to show implicit learning of a rule. Two experiments are reported here which show that it is not necessary to learn this rule in order to perform at above-chance levels on this test. Most of the effect can be explained in terms of the rejection of particularly distinctive test items that are more prevalent in the test negatives. This rejection appears to be mediated by knowledge that is potentially explicit as opposed to implicit, and we present tentative evidence that it is rule-based as opposed to analogic.