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Sensory horizons, reality monitoring, and the higher-order nature of consciousness: A critical look
Published online by Cambridge University Press: 25 June 2026
Abstract
Fleming and Michel’s hypothesis about the origins of consciousness not only faces multiple challenges but also overlooks phenomenal experience—the very phenomenon that needs explaining. Although we are in broad agreement with the authors’ overall perspective, we highlight challenges and suggest that consciousness evolved to attribute subjective value, enabling organisms to care about and act upon what they sense.
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References
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Fleming and Michel open their article by stating that “It is not obvious why we are conscious.” To us, however, it’s not obvious that they address this issue at all. In attempting to weave together different speculations about visual consciousness and its evolution into a single coherent narrative, Fleming and Michel end up leaving out the very phenomenon that calls for an explanation—phenomenal experience. While their evolutionary approach is certainly appealing, we think its narrow focus on vision and reliance on elements of other theories of consciousness invite different challenges.
Are underwater sensory horizons truly so limited?
Fleming and Michel’s first claim is that aquatic environments impose such severe constraints on visual range that slow, conscious vision would be useless there, and that the water-to-land transition therefore opened the door to qualitatively different cognitive uses of vision. While light scattering in water is indeed greater than in air, many aquatic animals have developed other sensory systems for detecting objects well beyond the “one or two body lengths” cited by the authors. Sharks, for example, exploit the fact that water carries sound waves faster and further than air and have a sense of hearing that allows them to detect potential prey at distances of hundreds of meters (Nelson & Gruber, Reference Nelson and Gruber1963; Nelson & Johnson, Reference Nelson and Johnson1972; Myrberg, Gordon & Klimley, Reference Myrberg, Gordon, Klimley, Schuijf and Hawkins1976; Myrberg, Reference Myrberg2001). Thus, it is audition, and not vision, that these animals exploit for the purpose of early detection and planning. If we broaden the concept of “sensory horizon” to include all modalities relevant to navigation and foraging, such as hearing and electroreception, the water–land contrast becomes less categorical, and the ecological argument for a unique terrestrial trigger (cf. MacIver et al., Reference MacIver, Schmitz, Mugan, Murphey and Mobley2017; MacIver & Finlay, Reference MacIver and Finlay2022) for the expansion of the sensory horizon correspondingly weaker.
Model-based planning without consciousness
Even if we grant that larger sensory horizons enable more sophisticated behavioral strategies, it does not follow that such strategies require or should result in phenomenal awareness. Fleming and Michel equate the emergence of model-based planning with the evolutionary onset of consciousness, but numerous examples show that model-based processes can operate in the absence of awareness. Artificial reinforcement learning systems such as AlphaZero (Silver et al., Reference Silver, Hubert, Schrittwieser, Antonoglou, Lai, Guez, Lanctot, Sifre, Kumaran, Graepel, Lillicrap, Simonyan and Hassabis2018) and MuZero (Schrittwieser et al., Reference Schrittwieser, Antonoglou, Hubert, Simonyan, Sifre, Schmitt, Guez, Lockhart, Hassabis, Graepel, Lillicrap and Silver2020) construct and exploit internal models of their task environments to plan sequences of actions many steps ahead, all absent of any phenomenology. Even in the biological realm, evidence from animal navigation suggests that certain planning-like behaviors can be implemented by neural circuitry without conscious mediation. The hippocampal “replay” of possible routes in rodents, often occurring during sleep or micro-rest states, supports flexible behavior but is unlikely to involve subjective experience (Ólafsdóttir et al., Reference Ólafsdóttir, Barry, Saleem, Hassabis and Spiers2015; Pfeiffer & Foster, Reference Pfeiffer and Foster2013). In short, although model-based planning could be associated with consciousness, it certainly is not diagnostic of it.
Phenomenality does not depend on reality monitoring
The third step in Fleming and Michel’s reasoning is that the capacity to imagine possible futures, as enabled by large sensory horizons, makes it necessary to distinguish reality from imagination. While we agree that this kind of “reality monitoring” (Johnson & Raye, Reference Johnson and Raye1981; Lau, Reference Lau2022) is essential to organisms capable of conscious mental imagery, we fail to see how it could explain the origins of subjective experience. Hallucinations, dreams, and mental imagery can be phenomenally rich despite being internally generated (Hobson, Reference Hobson2009; Pearson et al., Reference Pearson, Naselaris, Holmes and Kosslyn2015). The distinction between “real” and “imagined” applies to the source of content, but has no implications with respect to phenomenality. An animal could in principle excel at reality monitoring while representing its internally generated contents entirely unconsciously. Conversely, conscious experiences can occur despite inaccurate reality monitoring, as in certain psychotic states or in hypnagogic imagery (Waters et al., Reference Waters, Collerton, Ffytche, Jardri, Pins, Dudley and Larøi2012). The two dimensions – phenomenal character and reality attribution – are conceptually and empirically dissociable. This undermines the authors’ claim that conscious vision is a result of reality monitoring.
A higher-order theory in ecological clothing
Finally, when Fleming and Michel describe the perceptual reality monitoring system (Lau, Reference Lau2022), it becomes clear that it depends on the capacity to form representations about other internal representations (i.e., metarepresentations). For instance, such a system may tag a perceptual state as externally or internally caused. But this metarepresentational capacity is precisely the core commitment of higher-order theories (HOT; see Rosenthal, Reference Rosenthal2005; Lau & Rosenthal, Reference Lau and Rosenthal2011). On these accounts, a mental state is conscious when it is the target of an appropriate higher-order representation. Phenomenal character arises from the way a first-order state is described or qualified by the higher-order system, but this seems to require more than merely tagging that state with a “vividness index” (see previous point). The authors’ “reality monitoring” is thus not a novel functional theory but a restatement of the HOT framework embedded in an evolutionary narrative about sensory horizons. This is a welcome move, but one that seems to supplement, rather than supersede, the core conceptual commitments of HOT.
Conclusion
Fleming and Michel’s target article makes an ambitious attempt to link sensory ecology, cognitive control architectures, and theories of consciousness into a single evolutionary story. We have argued that each step in their chain of reasoning is open to challenge. Underwater sensory horizons are not uniformly short, and other modalities can extend them considerably; model-based planning can occur without consciousness; reality monitoring does not entail phenomenality; and the proposed mechanism is best seen as a specific instantiation of higher-order theory. But if that’s not enough for consciousness, then what is missing?
We suggest that phenomenal character emerged not as the result of reality monitoring, but rather as a way of signaling good and bad conditions (and decisions) to an organism (James, Reference James1890; Moncoucy et al., Reference Moncoucy, Dołęga, Tallon-Baudry, Cleeremans, Fitch, Allen and Roskiesforthcoming). What consciousness does is to make it possible for us to feel things; in other words, the core function of phenomenal consciousness is to enable organisms to attribute subjective value to what they sense. And from there, as (Mitchell, Reference Mitchell2023) puts it, living organisms become “loci of concern” in that “things matter to them” (p. 298). Likewise, consciousness matters: what we do is shaped by what we want to feel.
Acknowledgments
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Financial support
Axel Cleeremans is a Research Director with the F.R.S.-FNRS (Belgium) and a fellow of the Canadian Institute for Advanced Research (Brain, Mind and Consciousness program). This work was supported by European Research Council Advanced Grant #101055060 “EXPERIENCE” to Axel Cleeremans.
Competing interests
The authors declare no competing interests.