Behaviours and their underlying cognitive mechanisms come into action not in isolation but in a world that is naturally social and rich in context. Human behaviour is situated within an ongoing and dynamic interplay between cognitive processes and the contexts in which they operate. This symposium sets out to explore the relationship between higher order social factors and the building blocks of human cognition. We will share evidence that demonstrates the sensitivity of behavioural effects to context, with a focus on social context modulations. We will draw on research from task instruction, attentional capture and gaze, collaborative visual search, and joint action control research. Bringing together a variety of researchers across different fields in cognitive psychology, we aim to show the boundary conditions under which social contexts impact on (joint) task performance, reflected in benefits or costs.