Perceptual load improves the expression but not learning of relevant sequence information

In two experiments, we investigated the hypothesis of Rowland and Shanks (2006a) that sequence learning of relevant information is resistant to variations in perceptual load. Under conditions of increased selection difficulty, participants incidentally learned a sequence of targets presented together with three distractors. Target and distractors were composed of pairs of letters and shared more or less features with each other, rendering perceptual identification of the target either more (high load) or less (low load) attention demanding. The expression of sequence learning improved significantly under high load conditions as compared to low load conditions. This could indicate that the cognitive system promotes the development of response-based sequence learning in order to cope with the attentional demands arising from high perceptual load. However, the learning process proved to be unaffected by perceptual load when tested under baseline conditions without distractors (Experiment 1) or under opposite load conditions as during training (Experiment 2). This demonstrates that sequence learning is not influenced by increasing selection demands and suggests that sequence learning runs independently of input attention.