Henri Ey suggested that all hallucinations occur against the background of depersonalization, which is an alteration in experience that people find hard to describe, where the subject feels a strangeness pervading the world and her/his own body, emotions and thoughts. Embracing Ey’s proposal, this paper draws a comparison between depersonalization in hallucinations and depersonalization in some delusional states (especially the Capgras and the Cotard syndromes), which by the most recent models used in cognitive neuroscience is considered to be a disruption in so-called ‘affective familiarity’. Sensory information regarding the world is divided into the ‘overt pathway’ of perceptual inputs and the ‘covert pathway’ of ‘atmospheric cues’. In hallucinating subjects, we suggest that a breakdown of the grasping of atmospheric qualities in the environment triggers a compensatory process consisting of the production of hypotheses that make sense of the world perceived. Finally, we report on a case that illustrates our proposal.