Most theories of brain hemispheric lateralisation propose that the most prevalent, prototypical segregation of asymmetries, observed in the population has cognitive advantages. However, the cognitive implications of deviation from this pattern remain elusive. Previous research has faced challenges in addressing these questions, primarily because (1) deviations from prototypical organisation are rare, making it difficult to find individuals with less common asymmetrical patterns; (2) there is a predominant focus on single asymmetrical functions, not taking effects due to relationships between lateralised functions into account; and (3) asymmetrical processes are often compared for groups, which can naively discard within-group variability that is especially important for clinical groups, such as individuals with dyslexia. This project takes a multifaceted and individualised approach to overcome these challenges. It will (1) examine the cognitive impact of functional hemispheric segregation by examining the impact of multiple asymmetries in a large sample of healthy individuals, (2) explore the clinical relevance of hemispheric asymmetry in a group of individuals with dyslexia, and (3) investigate the consequences of atypical asymmetrical systems on hemispheric integration. This novel project represents the first detailed examination of the inter-relationship between asymmetries and their effects on behaviour, both in a normal and clinical population.