Task-irrelevant perceptual expertise

Abstract

Perceptual learning (PL) and perceptual expertise (PE) are two fields of visual training studies that investigate how practice improves visual performance. However, previous research suggests that PL can be acquired in a task-irrelevant manner while PE cannot and that PL is highly specific to the training objects and conditions while PE generalizes. These differences are difficult to interpret since PL and PE studies tend to differ on multiple dimensions. We designed a training study with novel objects to compare PL and PE while varying only the training task, such that the training objects, visual field, training duration, and type of learning assessment were kept constant. Manipulations of the training task sufficed to produce the standard effects obtained in PE and PL. In contrast to prior studies, we demonstrated that some degree of PE can be acquired in a task-irrelevant manner, similar to PL. Task-irrelevant PE resulted in similar shape matching ability compared to the directly trained PE. In addition, learning in both PE and PL generalizes to different untrained conditions, which does not support the idea that PE generalizes while PL is specific. Degrees of generalization can be explained by considering the psychological space of the stimuli used for training and the test of transfer.

Figure 1

The two sets of Ziggerins in silhouette formats used for the training. Each set has 6 basic shapes (objects in different rows), each shape was subtly varied in shape and part configuration to create another three exemplars (objects in different columns). The brackets illustrate the objects used as training exemplars, novel exemplars and novel category for one subject (counterbalanced across subjects).

Figure 2

A schematic illustration of the training and testing procedures.

Figure 3

The visual search training used in PL (top) and the shape naming training used in PE (bottom).

Figure 4

a) Visual search pre- and post test. b) Peripheral matching pre- and post-tests. c) Central matching pre- and post tests. d) The periphery-matching task used during retest 6–22 months after subjects completed their training.

Figure 5

Training effects of the PL group (A) and the PE group (B). For the PE group, the accuracy was scaled to that relative to all 18 objects such that performance during the four different training phases with different numbers of training objects (4, 8, 12 or 18) are comparable. The dotted line on (B) indicates chance level for the naming task. Error bars plot the standard error of each data point.

Figure 6

Performance for the periphery matching task before and after training using the noise threshold measure for PE (A) and PL (B), and the duration threshold measure for PE (C) and PL (D).

Figure 7

Performance for the central matching task before and after training using the noise threshold measure for PE (A) and PL (B), and the duration threshold measure for PE (C) and PL (D).

Figure 8

Performance for the visual search task before and after training for PL (A) and PE (B).

Figure 9

Performance for the second periphery matching task during posttest 3.