Fig 1.
Experimental procedure with the different tests presented before and after 18 months of music training.
Table 1.
Pre- and post-training results for the different tests.
Fig 2.
Pre- and post-training results for all tests.
A. Results for total Intelligence Quotient (IQ) score, for the four subtests of the reduced version of WISC-IV and for the digit span test are compared in the pre- and post-music training sessions. B. Results at the d2-R and NEPSY-II subtests are compared in the pre- and post-music training sessions. For both A and B, standard scores are indicated on the left ordinate and z-scores on the right ordinate. C. Results at the Alouette reading test and at the phonological tests are compared in the pre- and post-music training sessions. Z-scores are indicated on the left ordinate. Significant pre vs post differences with *: p < .05; ***: p < .001; ns: not significant. Error bars are standard errors of mean (SEM).
Fig 3.
Violin plots for each test showing significant improvements from pre to post-music training.
Violin plots (R Development Core Team, 2018) show the shape of the distribution. Each black dot represents one child, the red dot corresponds to the mean and the red line to the standard deviation (SD). Z-scores are indicated on the ordinate.
Fig 4.
Results of cluster analyses for the five tests showing significant post minus pre- music training differences.
For each test, each box plot corresponds to one cluster and the dots represent the children within each cluster. For each box plot, the upper quartile, the median and the lower quartile are represented together with the upper and lower whiskers. Significant increases or decreases in post minus pre-differences compared to 0 (no change) are indicated with *: p < .05; **: p < .01 and ***: p < .001.
Table 2.
Results of clusters analyses.
Fig 5.
Results of simple regression analysis showing a significant correlation (p < .001) between initial IQ score and improvement in IQ.
Table 3.
Comparison of improvement in IQ scores across different experiments using test-re-test procedures with different repetition intervals.