Umwelten

Philosophy of neurodivergent experience

11 min read

Summary

This wiki is named after an idea it has not yet examined directly.

Jakob von Uexküll coined Umwelt in 1934 to describe the perceptual world unique to each organism: the sensory reality constructed by its particular nervous system from the raw material of its environment. A tick’s umwelt is built from temperature gradients and the smell of butyric acid. A bat’s from the echoes of its own vocalisations bouncing off surfaces in the dark. A bee’s from polarised light and magnetic fields that human eyes cannot detect. Each organism inhabits a world shaped by what its body can sense, and that world is, for that organism, the whole of reality.

Uexküll was writing about animals. But the philosophical implications extend directly to human neurological difference. If sensory processing shapes perceptual reality, and if autistic sensory processing differs from neurotypical sensory processing in systematic and well-documented ways (see Sensory processing in autism and intellectual disability), then autistic people and neurotypical people do not merely interpret the same world differently. They inhabit, in Uexküll’s precise sense, different umwelten. Same room, same conversation, different perceptual realities.

This page explores what that means: for consciousness, for selfhood, for the possibility of mutual understanding, and for the obligations that arise when people who inhabit different worlds must share the same spaces.

The Umwelt problem

Uexküll’s original insight was about the relationship between organism and environment. He argued against the idea of a single objective environment that all organisms share. There is no “neutral” environment; there is only the environment as a particular nervous system constructs it. The tick does not experience the forest. It experiences warmth, butyric acid, and the texture of skin. Everything else is simply absent from its world.

Applied to neurodivergence, the implications are specific and testable. An autistic person in a supermarket does not experience the same supermarket as a neurotypical person. The fluorescent lights that a neurotypical shopper does not consciously register are, for some autistic people, a pulsing visual disturbance that consumes attentional resources. The background music that provides ambient texture for one person is a competing auditory stream that a different nervous system cannot filter from speech. The social signals (a cashier’s smile, another shopper’s body language) that one person reads automatically require effortful, conscious decoding for another.

These are not preferences or sensitivities. They are differences in what the nervous system presents to consciousness as “the world.” The neurotypical shopper and the autistic shopper are constructing different perceptual realities from the same physical space, each as real and as complete as the other.

Predictive processing theory (see Predictive processing and autism) gives this a mechanism. On this account, the brain does not passively receive sensory input; it actively predicts what input will arrive and adjusts its model when predictions fail. Autistic brains appear to weight prediction errors differently, giving more salience to raw sensory data and less to top-down predictions. The result is a perceptual world with higher fidelity and less automatic filtering, a world in which more sensory detail reaches consciousness. This is not a failure of processing. It is a different balance between prediction and data, producing a different umwelt.

What is it like to be autistic?

Thomas Nagel’s 1974 paper “What Is It Like to Be a Bat?” asked whether we can ever understand the subjective experience of an organism with a radically different sensory apparatus. His answer was no, or close to it: we can know that bats use echolocation, we can describe its physics and neurobiology, but we cannot access what it feels like from the inside to perceive the world through sonar. The subjective character of experience resists third-person description.

Nagel chose bats because their primary sense is so different from ours that imaginative projection fails. We cannot imagine what echolocation is like by imagining ourselves doing it, because our imagining is anchored in visual and auditory frameworks that echolocation does not share.

The paper is almost never cited in the neurodiversity literature, which is strange, because it describes the central philosophical problem of cross-neurotype understanding with precision. Can a neurotypical person know what it is like to experience a supermarket when the fluorescent lights are a pulsing strobe, the background noise is an undifferentiated roar, and every social interaction requires conscious effort that would normally be automatic? Can they know what it is like when the label inside a shirt produces a sensation so aversive that it overwhelms the ability to think about anything else?

Nagel would say: probably not, in the strong sense. You can know that these experiences occur. You can take testimony seriously and adjust your behaviour accordingly. You can design environments that accommodate what you understand intellectually. But the qualitative character of the experience, what it feels like from inside that nervous system, remains inaccessible. The gap is not a failure of empathy. It is a structural feature of consciousness: subjective experience is anchored in the body that has it.

This is not a counsel of despair. It is a philosophical foundation for humility. The neurotypical parent who says “I understand” to their autistic child may understand a great deal, but they do not and cannot know what the child’s sensory world feels like. Acknowledging that gap honestly is more respectful than pretending it does not exist.

The body as subject

The phenomenological tradition, particularly Maurice Merleau-Ponty’s work on perception, provides another entry point. Merleau-Ponty argued that perception is not a cognitive process that happens to a body; it is something the body does. We do not first receive sensory data and then interpret it. We perceive through our bodies, and the body’s structure shapes what perception is possible. The body is not an instrument the mind uses; it is the subject of experience.

Boldsen (2018) applied this framework directly to autism, arguing that if we take Merleau-Ponty seriously, then autistic sensory differences are not distortions layered on top of a “normal” perceptual process. They constitute a different mode of embodied subjectivity. The autistic body perceives differently, and because perception is not separable from the body that does it, the autistic person is differently. Not deficiently. Differently.

In a follow-up study (2022), Boldsen conducted phenomenological fieldwork with autistic adolescents and young adults and identified three dimensions of how sensory differences reshape social experience. Social encounters registered as sensorially chaotic and unpredictable. Other people’s embodied expressions (facial movements, gestures, tone of voice) appeared unfamiliar or threatening, producing a pre-reflective sense of detachment. And participants employed deliberate practices to construct social meaning from experiences that did not yield it automatically.

This last finding is important. It is not that autistic people lack social understanding. It is that the route to social understanding runs through a different sensory landscape, and the usual shortcuts (automatic facial expression recognition, intuitive tone-of-voice reading, effortless gaze processing) are not available, or not available without cost. Social cognition becomes a conscious, effortful, constructed achievement rather than an automatic, pre-reflective one.

Masking (see Masking and camouflaging) looks different through this lens. It is not simply performing neurotypicality. It is a person whose body constructs social perception through effortful, conscious processing being required to produce outputs that match what automatic, pre-reflective processing would generate. The exhaustion that masking produces is not metaphorical. It is the metabolic cost of running a conscious process to do what another nervous system does without effort.

Degree or kind?

The philosophical question that the neurodiversity literature has largely avoided is whether the difference between neurotypical and neurodivergent experience is one of degree or one of kind.

If it is degree, then autistic sensory experience is a more intense or less filtered version of neurotypical sensory experience. The fluorescent lights bother everyone a little; they bother autistic people more. Social cues are effortful for everyone sometimes; they are effortful for autistic people more often. On this account, the gap between umwelten is crossable in principle: you already have the experience, just at lower intensity, so you can extrapolate.

If it is kind, then the situation is closer to Nagel’s bat. Autistic sensory processing does not produce a louder version of the same world. It produces a qualitatively different world, one that cannot be reached by extrapolation from neurotypical experience. The autistic person’s relationship to a fluorescent light is not a more intense version of the neurotypical person’s; it is a categorically different perceptual event, as different as echolocation is from vision.

The truth is probably not cleanly one or the other. Some sensory differences look like degree (greater sensitivity to noise, lower threshold for pain). Others look more like kind (synesthetic co-activations, altered temporal processing, different perceptual gestalt formation). Predictive processing theory suggests that the difference is architectural: not louder input but different weighting of input against prediction, which would produce experiential differences that are structural rather than scalar.

The practical consequence matters. If degree, then neurotypical people can be educated to understand autistic experience through empathy and imagination. If kind, then understanding requires something more like trust: accepting testimony about experiences you cannot simulate internally. The double empathy problem (see The double empathy problem) suggests that the gap runs both ways and is structural rather than merely informational, which points toward kind.

Selfhood and sensory experience

If perception is embodied (Merleau-Ponty), and if different bodies produce different perceptual worlds (Uexküll), then neurological difference does not just change what you experience. It changes who you are.

This is not a metaphor. Sense of self is partly constituted by sensory experience. The proprioceptive awareness of where your body is in space, the interoceptive signals that tell you whether you are hungry or anxious or cold (see Interoception in autism), the vestibular sense that grounds you in gravity: these are not additions to selfhood. They are ingredients of it. When interoceptive signals are muted or difficult to interpret (see Alexithymia and autism), the experience of being a self changes. When proprioceptive processing differs, the felt boundary between self and world shifts.

Late-diagnosed autistic adults frequently describe the experience of having lived inside a self they did not fully understand. The diagnosis provides a framework, but the underlying experience was always there: a sensory relationship to the world that did not match the neurotypical model, producing a self-experience that the available concepts could not capture. This is hermeneutical injustice (Fricker, 2007) at the most intimate level: not having the concepts to understand your own inner life.

Open questions

Can phenomenological methods access autistic experience on its own terms, or does the tradition carry neurotypical assumptions that distort what it studies? Hughes, Ekdahl, and Boldsen (2025) raised this concern, noting that phenomenological autism research often struggles to avoid framing autistic experience as deficient even when that is not the intention. The methods themselves may need to be neurodiversified.

Is there a phenomenology of the ID gap? (See Sensory processing in autism and intellectual disability.) Most philosophical work on neurodivergent experience focuses on autistic people who can articulate their experience verbally. For people with intellectual disabilities who cannot provide first-person testimony in standard forms, the philosophical questions become harder and more urgent: how do we understand their umwelt without projecting our own? What counts as evidence of subjective experience when verbal report is not available?

What would a philosophy built from neurodivergent experience look like, rather than one that takes neurotypical experience as default and accommodates exceptions? This is the question that connects this page to Socratic inquiry and neurodivergent knowledge, and it does not yet have an answer.

Key sources

  • Boldsen, S. (2018). Toward a phenomenological account of embodied subjectivity in autism. Culture, Medicine, and Psychiatry, 42, 893–913. doi: 10.1007/s11013-018-9590-y
  • Boldsen, S. (2022). Autism and the sensory disruption of social experience. Frontiers in Psychology, 13, 874268. doi: 10.3389/fpsyg.2022.874268
  • Chapman, R. and Carel, H. (2022). Neurodiversity, epistemic injustice, and the good human life. Journal of Social Philosophy, 53(4), 614–631. doi: 10.1111/josp.12456
  • Fricker, M. (2007). Epistemic Injustice: Power and the Ethics of Knowing. Oxford: Oxford University Press.
  • Hughes, E., Ekdahl, D., and Boldsen, S. (2025). Between essence and diversity: challenges for phenomenological autism research. Theory & Psychology. doi: 10.1177/09593543251315074
  • Merleau-Ponty, M. (1945/2012). Phenomenology of Perception. Trans. D. Landes. London: Routledge.
  • Nagel, T. (1974). What is it like to be a bat? The Philosophical Review, 83(4), 435–450.
  • Uexküll, J. von (1934/2010). A Foray into the Worlds of Animals and Humans. Trans. J. O’Neil. Minneapolis: University of Minnesota Press.

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