When attention interrupts learning: inhibitory effects of attention on TIPL

Abstract

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.

Figure 1

Illustration of the general experimental procedure. (a) Outline: experiment consisted of a pre-test session, ten training sessions, and a post-test session, in that order. (b) Procedure of the task in pre- and post-test sessions. In each trial, dynamic random dot (DRD) displays were presented on the right or left side of the screen. Some of these dots moved coherently in one of three directions — 15°, 135° and 255°. 400ms later, this display was replaced with three arrows. Subjects selected the arrow that best matched their perceived direction. Their performance was measured in four coherence levels — 5,10,15 and 20%. (c) Procedure of the task in training sessions. In each trial, two DRD displays with 0% coherence level were presented on both sides of the screen (one on each side). After a period of 400, 800, 1200 or 1600ms, a row of five arrows appeared above or below a fixation point for 400ms. (For convenience, only three arrows appear in this figure.) While the arrows were presented 5% of the dots in lateral DRD displays moved coherently in directions different from each other. (The big grey arrow in the figure represents the direction of coherent motion.) As soon as the arrows disappeared, all dots of the DRD displays moved randomly again. Subjects were asked to report the orientation of the arrows. The row of arrows played two roles. It was the task-relevant stimulus of the main task: subjects had to report its orientation; it also worked as an exogenous attentional orienting cue. Arrows could automatically trigger attentional orienting, so that subjects would pay attention involuntarily to where the arrow pointed.

Figure 2

Mean correct percentage (a) for a direction presented on an attended side during training sessions, (b) for a direction on an unattended side, and (c) for a direction never exposed. The learning effect was found only for the unattended direction and the control direction, and not for the attended direction.

Figure 3

Mean performance improvement for each direction, as determined by subtraction of % correct performances in the pre-test from the % correct performances in the post-test.