Modelling perception as a hierarchical competition 11 require a detailed understanding of how neural representations of internally and externally generated perceptual content interact. Future studies may seek to explore the predicted impact of hierar-chical competition on neural activity using alternative models of feedforward-feedback interference, although our model still capa-bly emulates findings on how imagined and veridical information is distributed in real human brains (e. g. Lee et al. 2012 ; Van Rullen and Reddy 2019; Spagna et al. 2021). Conclusion Overall, this work provides a formal framework for explaining the unique quasi-sensory experience of mental imagery. We pro-pose that internally generated thoughts are experienced along an axis from highly abstract to highly sensory in nature, aligning with the degree of dimensionality that a given thought is rep-resented in. Under this assumption, we show that competition from bottom-up sensory input may prevent imagined stimuli from being perceived in any substantially sensory way. Accounting for competition in a hierarchical system can therefore provide suffi-cient conditions for distinguishing imagined, veridical, and hallu-cinatory perception, as well as variation within these phenomena. As modelling imagery competitively may resolve major lingering questions in imagery research, we recommend that future studies investigate the exact manner by which internally and externally generated stimuli may be combined in the brain. Ultimately, we conclude that mental imagery is most logically understood as an intrinsically competitive process and should be largely considered as such in ongoing research. Funding A. A. S was supported by an Australian Government Research Training Program Scholarship. A. K. R. was supported by an Aus-tralian Research Council Discovery Early Career Researcher Award (DE200101159). 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