Clarifying the concept of visual load: a systematic review

Vision dominates human information processing, but visual load (VL) lacks a clear definition. Following PRISMA guidelines, this systematic review searched the Web of Science Core Collection, MEDLINE, and PsycINFO. 119 studies were included for analysis. Only 12 (10%) studies explicitly defined VL, and the definitions were highly heterogeneous. Various methods have been used to manipulate and measure VL, reflecting the lack of a unified framework. Our findings reveal that conceptual ambiguity impairs study comparability and practical use. We propose that VL should be conceptualised as the total visual processing demand imposed on an individual during visual tasks, encompassing three key dimensions: perception, cognition, and responding.