Multimodal colour modulation for cognitive enhancement in intelligent rehabilitation: a systematic review and translational guidance

BACKGROUND: Colour modulation has been investigated as a non-invasive means of supporting cognitive performance, yet translation to rehabilitation-oriented applications has been constrained by fragmented evidence, inconsistent parameterisation, and heterogeneous assessment strategies. MAIN BODY: This systematic review synthesises 75 studies published between 2011 and 2025 through a Colour-Modality-Cognition framework that links stimulus design, measurement strategy, and cognitive goals. Across the evidence base, a graded and context-dependent pattern emerged. Contrast-related variables, particularly lightness and colour difference, showed more consistent support for baseline legibility and task reachability, whereas hue- and chroma-related effects were more conditional on task family, visual context, implementation locus, and the baseline contrast conditions already in place. Across several studies, efficiency-related changes, including shorter search times or reduced cortical load, were more readily captured by ocular and neurophysiological measures than by behavioural outcomes alone, especially where behavioural performance approached ceiling levels. However, the literature rarely assessed post-training retention, transfer, or other longer-term rehabilitation-relevant outcomes. CONCLUSION: Current evidence supports a more explicit framework for the design and evaluation of rehabilitation-oriented colour interventions, particularly in relation to contrast-secured visual design and the use of multimodal assessment. However, implications for adaptive rehabilitation systems remain preliminary because most available evidence derives from controlled, predominantly non-clinical task settings rather than direct rehabilitation deployment.