Determining the relationship between the n-Back Task, Symbol Span subtest, Digit Span subtest and Symbol Digits Modality Test

Abstract

Research in cognitive psychology has highlighted the importance of working memory and information processing speed in cognitive functioning (Chai et al., 2018; van der Fels et al., 2015). While the n-back test is widely considered a measure of working memory, its construct validity remains debated, with some evidence suggesting it may also reflect processing speed (Andrade, 2002; Jaeggi et al., 2010). This study examined the relationship between the n-back test, two established measures of working memory (Digit Span and Symbol Span), and a processing speed measure (Symbol Digit Modality Test) to investigate the n-back’s concurrent and construct validity. Additionally, the influence of biological sex and socioeconomic status (SES) on cognitive performance was explored. A sample of 70 young adults (ages 18-25) completed these cognitive assessments. Results indicated that processing speed (SDMT) was the strongest predictor of n-back performance, suggesting that the n-back test may rely on cognitive mechanisms beyond core working memory. SES significantly influenced processing speed and higher-order working memory tasks, while biological sex differences emerged in the Digit Span Backward and 3-back tasks, with males showing an advantage. These findings contribute to the ongoing debate about the n-back test’s validity as a pure working memory measure and emphasize the need to consider demographic factors when interpreting cognitive assessments. Future research should further examine the interplay between working memory, processing speed, and demographic influences in more diverse and larger samples.