Investigating the Relationship Between Subjective Sleep Quality and Statistical Language Learning

Statistical learning is a universal cognitive mechanism that allows humans to detect patterns and regularities in their environment, playing a crucial role in various cognitive functions, including language acquisition. This research delved into the relationship between subjective sleep quality, measured using the PSQI (Pittsburgh Sleep Quality Index) questionnaire, and statistical language learning in adults. In two separate studies, participants' performances in statistical language learning were measured: Study 1 (N = 97) and its replication in Study 2 (N = 120). Both studies utilised the two-alternative forced choice (2AFC) recognition task, complemented by a confidence judgement rating. The results showed a significant learning effect above chance in both studies, highlighting adults' capability for statistical language learning. Explicit learning mechanisms significantly contributed to statistical language learning, highlighting the vital role of the declarative memory hippocampal-prefrontal cortex system in adult statistical language learning. Study 1 found that a logarithmic model most suitably represented the relationship between subjective sleep quality and statistical language learning performance. This model showed an initial drop in learning performance as subjective sleep quality declined, but performance stabilised with a further decline in subjective sleep quality. However, this relationship was not statistically significant in Study 2. While this research provides novel insights into the interplay between sleep quality and statistical language learning, future studies should consider subjective and objective sleep measures for a more comprehensive investigation. The research findings have implications for understanding the cognitive mechanisms underpinning language learning and the potential influence of sleep quality on these processes