Working memory training shows immediate and long-term effects on cognitive performance in children

Abstract

Working memory is important for mental reasoning and learning processes. Several studies in adults and school-age children have shown performance improvement in cognitive tests after working memory training. Our aim was to examine not only immediate but also long-term effects of intensive working memory training on cognitive performance tests in children. Fourteen healthy male subjects between 10 and 16 years trained a visuospatial n-back task over 3 weeks (30 min daily), while 15 individuals of the same age range served as a passive control group. Significant differences in immediate (after 3 weeks of training) and long-term effects (after 2-6 months) in an auditory n-back task were observed compared to controls (2.5 fold immediate and 4.7 fold long-term increase in the training group compared to the controls). The improvement was more pronounced in subjects who improved their performance during the training. Other cognitive functions (matrices test and Stroop task) did not change when comparing the training group to the control group. We conclude that visuospatial working memory training in children boosts performance in similar memory tasks such as the auditory n-back task. The sustained performance improvement several months after the training supports the effectiveness of the training.

Figure 1.. Timeline of the experiment and study procedure.

Cognitive testing included two working memory tasks (auditory n-back and letter-number sequencing), a fluid intelligence task [matrix reasoning task, TONI-IV (Test of Non-verbal Intelligence Version IV)], two cognitive control tasks (Stroop and Flanker task), two processing speed tasks (symbol search and digit-symbol substitution task) and a short-term memory task (number-span task). In addition, subjective motivation and concentration were measured on a scale from 1 (minimal) to 10 (maximal).

Figure 2.. Individual training performance (first session, session of maximal performance, last session).

Individual training performance (first session, session of maximal performance, last session) is shown. Each solid line represents the performance of an individual (N = 14) in the visuospatial n-back (VNB) task training mean n of VNB at the first training session (circle), at the session of maximal performance (triangle) and at the last training session (square). The dashed line represents the average performance at the first session, the session of maximal performance and the performance at the last session. Average maximal performance was reached between session 10 and 11 (mean 10.21 ± SEM 1.22) and average performance at the last session was reached between session 16 and 17 (16.14 ± 1.19). ** indicates: performance at session of maximal performance was significantly higher than performance at the first and the last training session. * indicates: performance at the last session was significantly higher than at the first session.

Figure 3.. Age at the first training session.

Correlation between age (years) and performance at the first session of visuospatial n-back training (Pearson correlation, r = 0.76, p < 0.05).

Figure 4.. Mean ± SEM of maximal n (auditory n-back, ANB) per group and test session (PRE, POST, FU).

The training group showed a significant increase from PRE to POST and to FU. The control group showed a significant increase from PRE to POST, but not FU. * indicates significant changes within group (training (red), control (black); paired t-test, p < 0.05. # indicates significant performance difference at the respective test session (unpaired t-test, p < 0.05)).

Figure 5.. Association between visuospatial training performance increase and auditory n-back (ANB) performance increase.

Correlation of training gain (diffMx, difference between Maximal Performance and performance at the first training session) with the change in ANB from PRE to POST (r = 0.76, p < 0.05).

Figure 6.. Visuospatial training performance for the steady and unsteady performers.

Steady performers: individuals with a significant positive correlation between mean training performance (mean n) per session and the training session. Unsteady performers: no positive correlation. Left: mean ± SEM of n [visuospatial training task (VNB)] over each training session per group. Right: individual mean n (VNB) per training session. Blue: steady performer group. Green: unsteady performer group. # indicates significant performance differences between steady and unsteady performers at the first and the last session (unpaired t-test, p < 0.05).

Figure 7.. Mean ± SEM in auditory n-back (ANB) for the steady and unsteady training performers.

* indicates significant changes within groups [steady performers (blue), unsteady performers (green)]. # indicates p < 0.05 (unpaired t-test between sessions [PRE, POST, FU]).