Paradoxical benefits of dual-task contexts for visuomotor memory

Abstract

It is generally thought that increased attention helps when one is learning a new task. However, using a dual-task paradigm, we showed that the rate of visuomotor learning was the same regardless of attentional distraction caused by a secondary task. Yet, when participants were tested later, a motor skill learned under distraction was remembered only when a similar distraction was present; when participants were tested without the distracting task, their performance reverted to untrained levels. This paradoxical result, in which the level of performance decreases when more attentional resources are available, suggests that the dual-task context, or the lack thereof, acts as a vital context for learning. This task-context-dependent "savings" was evident even when the specific secondary task or sensory modality differed between learning and recall; thus, the dual tasking, rather than the specific stimuli, provides context. This discovery suggests that the success of learning and rehabilitation programs may be diminished if they are developed without consideration of the role of task contexts.

Keywords: attention; learning; memory; motor processes; task context.

© The Author(s) 2014.

Figures

Figure 1

Task schematics. A: Reaching task. Reach targets appeared one at a time and remained visible for the entire trial (1500 ms). In null trials, the cursor followed stylus motion normally, whereas in rotation trials, the cursor direction was rotated by 45° CCW from the reach trajectory. B–D: Secondary tasks. Five upright or inverted ‘T’s of various colors (B), five grey squares (1 cm2) of three different luminance levels (low, mid, high) (C), or five tones of three different frequencies (low, mid, high) (D) sequentially appeared for 150 ms with 150 ms gaps (total 1500 ms) in the RSVP tasks. In all tasks, participants had to report how many targets (1, 2 or 3) were presented in a sequence by pressing a keyboard key at the end of each trial with their left hand. Targets were defined by a single (e.g., low load: green T) or conjunction feature (e.g., high load: upright red and inverted green T) in the RSVP task (B), the low and high luminance squares in the brightness detection task (C) and the low and high frequency tones in the sound detection task (D). E: Secondary task performed in each group throughout each experimental phase.

Figure 2

Reach error (A–E) during the visuomotor adaptation task (averaged over blocks of 4 trials; mean ± SE; N = 9 in each group) and savings (F) in Experiment 1. A: Reaching error for None-None, Low-None, High-None, and High-High groups during the adaptation phase. All groups performed similarly regardless of attentional load. B–E: Reach error during the adaptation (open circle) and recall phases (solid circle) for the None-None (B), Low-None (C), High-None (D), and High-High groups (E). Gray areas in each figure indicate which blocks were used to calculate savings. F: Savings for the None-None, Low-None, High-None, and High-High groups. Only the None-None and High-High groups showed significant savings during recall.

Figure 3

Reach error (A–E) during the visuomotor adaptation task (averaged over blocks of 4 trials; mean ± SE; N = 10 in each group) and savings (F) in Experiment 2. Eye fixation was required within a 1° radius centered on the starting base. A–E: Reach error during the adaptation (open circle) and recall phases (solid circle) for the None-None (A), High-None (B), High-High (C), High-Brightness (D), and High-Sound groups (E). Gray areas in each figure indicate which blocks were used to calculate savings. F: Savings for the None-None, High-None, High-High, High-Brightness and High-Sound groups. The magnitude of savings was significantly higher for the None-None, High-High, High-Brightness, and High-Sound groups than for the High-None group.