When attention interrupts learning: inhibitory effects of attention on TIPL.

While task-irrelevant perceptual learning (TIPL) suggests that perceptual learning of a feature occurs without focused attention to the feature, some kind of attentional involvement was implied by recent findings that TIPL occurred only when a task-irrelevant stimulus was paired with a main task target. Here, during training, two task-irrelevant stimuli with different coherent motion directions were exposed, one on an attended side and the other on an unattended side. We found no performance improvements for the direction on the attended side. These results suggest that while attention facilitates task-relevant learning, it can suppress TIPL.