Learning one task by interleaving practice with another task

Abstract

Perceptual learning is a sustainable improvement in performance on a perceptual task following training. A hallmark of perceptual learning is task specificity - after participants have trained on and learned a particular task, learning rarely transfers to another task, even with identical stimuli. Accordingly, it is assumed that performing a task throughout training is a requirement for learning to occur on that specific task. Thus, interleaving training trials of a target task, with those of another task, should not improve performance on the target task. However, recent findings in audition show that interleaving two tasks during training can facilitate perceptual learning, even when the training on neither task yields learning on its own. Here we examined the role of cross-task training in the visual domain by training 4 groups of human observers for 3 consecutive days on an orientation comparison task (target task) and/or spatial-frequency comparison task (interleaving task). Interleaving small amounts of training on each task, which were ineffective alone, not only enabled learning on the target orientation task, as in audition, but also surpassed the learning attained by training on that task alone for the same total number of trials. This study illustrates that cross-task training in visual perceptual learning can be more effective than single-task training. The results reveal a comparable learning principle across modalities and demonstrate how to optimize training regimens to maximize perceptual learning.

Keywords: Comparison task; Cross-task training; Orientation; Perceptual learning; Spatial–frequency; Transfer.

Copyright © 2014 Elsevier Ltd. All rights reserved.

Figures

Figure 1

A. Trial sequence used for all groups. Each trial started with a 100-ms fixation cross, followed by a 50-ms temporal cue, followed by a 50-ms ISI, after which the two stimuli appeared for 100 ms. The stimuli included a standard stimulus (oriented at 30° or 300°) and a test stimulus which varied in spatial frequency or orientation depending on the task. The location of the standard (left or right) varied randomly in each trial. Observers had to compare the two stimuli and indicate which one was more clockwise (orientation task) or had a higher spatial frequency (spatial-frequency task). Each response was followed by an auditory cue indicating whether the response was correct. B. Procedure across groups (n=7 for each group). All observers participated in a pre-test and a post-test that included testing for the two tasks for the two standard stimuli (order counterbalanced). Each group underwent a different training procedure that was identical for the 3 training days. Groups “O-O-” and “F-F-” trained on orientation alternating with rest and rest alternating with spatial-frequency, respectively (400 trials). Group “OFOF” trained on orientation alternating with spatial frequency (400 trials on each task). Group “OOOO” trained only on orientation (800 trials).

Figure 2

Results of testing sessions for all groups (n=7 per group). A. Empty and filled bars indicate pretest and post-test accuracy (% correct), respectively. Results are shown separately for the two tasks and two orientations of the standard stimulus: red indicates orientation and grey spatial frequency for both trained and orthogonal (untrained) orientation. Group “OFOF” showed significant learning on the trained orientation condition (see text). Results show means across observers, error bars depict SEM.

Figure 3

Normalized improvement across days for all groups on the orientation task. The normalized amount of improvement was calculated for each observer by subtracting the % correct performance on the pre-test dayfrom that on each of days 2–5). Performance on the orientation task improved gradually across days for the cross-task group (“OFOF”; red symbols and line) but not for the other groups (“O-O-“, green symbols and line; “-F-F”, black symbols; “OOOO”, blue symbols and line). Results show means across observers, error bars depict SEM.

Figure 4

Pre-test and post-test performance on the orientation task of individual observers across groups. The dashed diagonal line indicates identical performance between pre-test and post-test. All observers from the cross-task group (red symbols, “OFOF”) are above the line and above observers from other groups (“O-O-“, green symbols; “-F-F”, black; “OOOO”, blue), showing the benefit of cross-task training.