Lifting the veil: Probing altered visual perception in derealisation

During an acute episode of depersonalisation/derealisation (DP/DR), people report a complex and idiosyncratic change in their perceptual experience. Specifically, derealisation describes the experience of detachment from the external world and altered visual perception in which the surroundings look faded, foggy or dream-like.Whilst some have argued that there may not be genuine perceptual changes in derealisation, this proposal is yet to be tested empirically. Thus, we set out to investigate the potential perceptual changes in derealisation. In this Registered Report, we conducted two online experiments to reveal the impact of DP/DR symptoms measured via the state version of the Cambridge Depersonalisation Scale (CDS) on how people evaluate (Experiment 1, N=200, CDS-state mean: 32.43 +/- 29.94 SD) and adjust (Experiment 2, N=125, CDS-state mean: 29.38 +/- 30.47 SD) naturalistic scene images with different levels of saturation and contrast. Participants were asked to rate how real the presented images look compared to their everyday experience (in Experiment 1) and to adjust the contrast or saturation level of images to match their everyday visual experience (in Experiment 2). We tested the effect of CDS-state scores on these subjective ratings via model comparison with Bayes Factors. In both experiments, we found strong evidence supporting the null models, suggesting that DP/DR symptoms did not affect realness ratings or vividness adjustments. These results provide empirical support for theories suggesting that self-reported altered vividness experience in derealisation does not reflect genuine perceptual changes, instead they signify the (meta-)cognitive interpretation of these experiences. We discuss pros and cons of the current research practices when assessing derealisation and highlight key avenues for the future investigation.