Background. Visuospatial working memory changes across years of schooling. According to data from the cross-sectional and longitudinal studies available in the literature, conclusions about the linear or nonlinear nature of changes in visuospatial working memory depend on the period of time analyzed and the frequency of the measurements. However, which of the two nonlinear models of functional dependence (e.g., quadratic or cubic) best describes the developmental trajectories of visuospatial memory across schooling is still an open question.
Objective. The results of statistical analysis of the development of visuospatial working memory in girls and boys across school years from Grade 1 to Grade 11 are presented. Additionally, the relationship between age and years of schooling is investigated, as is the influence of these factors on the developmental trajectory of visuospatial working memory.
Design. This cross-sectional study involved 1,246 pupils who were in Grades 1 to 11 at one public school; their ages ranged from 6.8 to 19.1 years (50.4% were boys). The students’ visuospatial working memory was measured using the computerized “Sequences” test, which is based on the “Corsi block-tapping task” and has been adapted for Russian schoolchildren. Correlations, dispersion analysis, and polynomial regression were carried out, and both linear and nonlinear models of the functional dependence of working memory on years of schooling were tested.
Results. The results of the multiple regression analysis suggest that number of years of schooling is a more important factor than age with regard to temporal changes in visuospatial working memory. When we introduced “years of schooling” and “age” predictors into a single model, we found the year of schooling to be the most significant predictor of visuospatial working memory (β = 1.07;p = 0.000).While age remained a statistically significant predictor (β = -0.52;p = 0.008), it did not significantly improve the model characteristics (corrected R2 = 0.30; F(2) = 253.9; p<0.01).
The results of the polynomial regression showed that during schooling, the developmental trajectories of visuospatial working memory are nonlinear for both genders. In girls, both the quadratic and cubic models explained 36% of the variance in visuospatial working memory, but the quadratic model had the least number of parameters and the best fit to data. In boys, despite all theoretical models being suitable, the largest percentage of the variance in visuospatial working memory values was explained using the cubic model (R2= 0.31; p = 0.000). Thus, the characteristic of change in visuospatial working memory for girls had a quadratic relationship that stabilized after Grade 8, while for boys, the relationship was cubic, with the period of stabilization between Grades 5 and 6, and then further growth.
Conclusion. We concluded that the number of years of study is an important factor in the development of visuospatial working memory during the schooling period, but that there are other factors involved as well.
Keywords: visuospatial working memory; school education; grade; age; cross-sectional study; polynomial regression; gender differences