Abstract
The visual system adapts to chromatic changes by altering its sensitivity to the environment. Research on chromatic adaptation under natural viewing has exposed observers to simple transformations using filters or lenses (Neitz et al.,2002, Engel et al., 2016). It is an open question whether our visual system adapts to complex chromatic transformations as it does for complex visuospatial manipulations (Richter et al., 2002). Altered reality (AR) devices allow us to address this question. Grush et al., (2015) provided qualitative evidence from two observers that their perceptual experience of colour was altered after AR exposure to a hue-rotated world. We exposed observers to a real-time pass-through feed in an AR headset (Meta Quest 3), applying a hue rotation of 120 degrees in HSL space (e.g., blue sky turns magenta). Observers (N = 8) were immersed in either a positive or negative hue rotation during which they interacted with the unnaturally coloured world through everyday activities including walking in nature, painting, selecting and eating food, etc. We measured the observers’ perception of unique yellow and unique blue prior to adaptation and each hour during their exposure to the hue-rotated world, for up to four hours. Our results expose the limits of visual adaptability, elucidating whether adaptation extends to unnatural chromatic transformations and attempt to shed light on the temporal characteristics of long-term adaptation.
 Funding: Funding from the European Research Council (ERC) under the Horizon 2020 research and innovation programme (Project COLOURMIND: Grant agreement No. 772193, to A.F.) and a University of Sussex PhD studentship to Y.K.