A seven-year-old watches a delayed image of her own hand move. An adult does the same. So does someone in their seventies. The physical hand is unquestionably theirs, yet the visual evidence arrives late enough to make ownership less certain.
That small disturbance creates a useful question. If the body changes dramatically across childhood, adulthood and ageing, what keeps the felt sense that this body is mine relatively stable?
Marieke Weijs, Marte Roel Lesur, Moritz Daum and Bigna Lenggenhager addressed that question in a 2024 Cortex study spanning participants from 7 to 80 years of age. Rather than asking whether older people simply have weaker body ownership, they tested how the nervous system weighs conflicting visual, tactile and motor information across the lifespan.
The result is not a story of decline. It is a story of changing weights.
Source card
The study, Keeping up with ourselves: Multimodal processes underlying body ownership across the lifespan, was published in Cortex, volume 177, pages 209–223, with DOI 10.1016/j.cortex.2024.05.013. The published sample included 154 healthy right-handed participants organized for recruitment into seven age groups of 22, spanning ages 7 to 80.
Participants saw their own hand in mixed reality while either moving it or receiving touch. The visual image was presented with different temporal delays. After trials, participants judged synchrony and rated ownership of the seen hand. The researchers also assessed visual dependence and proprioceptive acuity.
This design matters because body ownership is not measured by asking a person whether they generally feel embodied. It is perturbed experimentally. The researchers create disagreement among sensory channels and observe how ownership changes as the disagreement grows.
The central finding: mismatch weakens ownership across age
Across the lifespan, increasing temporal mismatch reduced body ownership. When what participants saw became less synchronized with what they felt or did, the delayed hand felt less like their own.
This pattern appeared in both tactile and motor conditions. That supports a broad principle already familiar from body-ownership research: temporal congruence among sensory signals contributes to the construction of bodily selfhood.
The important word is contributes. The finding does not imply that ownership is a simple synchrony detector. People retained a sense of ownership under some conflict, and age changed the overall level of ownership in a way that was not reducible to the delay manipulation.
Ownership increased with age
The researchers found a higher reported sense of ownership with increasing age, independent of visual delay and modality.
That is not the result many readers would predict. Ageing is often described through sensory decline, so one might expect older adults to become less certain about bodily selfhood. The data instead suggest that older participants were, on average, more willing to retain ownership of the seen hand even while sensory information was being perturbed.
The authors interpret the pattern as at least partly compatible with increased weighting of top-down information and reduced weighting of incoming bottom-up signals in the momentary sense of bodily self with age.
This is an interpretation, not a direct measurement of “top-down weighting.” The experiment measured ownership ratings, synchrony judgments and selected perceptual variables. The computational weighting process is inferred from the pattern.
Delay sensitivity did not tell one clean developmental story
If ageing simply made people less sensitive to sensory mismatch, delay sensitivity should have changed consistently with age. It did not.
The relationship between age and sensitivity to the imposed delays was not consistent across the tested domains. That complicates any simple statement that older adults “ignore” sensory conflict.
It also protects against a common explanatory shortcut. A higher ownership rating in older adults cannot automatically be translated into poorer temporal resolution. People can maintain ownership for reasons that are not equivalent to failing to notice mismatch.
Visual dependence and proprioceptive acuity did not explain the age pattern
The researchers additionally assessed visual dependence and proprioceptive acuity. They did not find age effects on these measures that explained the ownership result.
This negative finding is scientifically useful. It removes two easy explanations from the centre of the account. If older participants had simply become much more visually dependent, or much less proprioceptively precise, the ownership result might have been reducible to those changes.
It was not.
The study therefore points toward a more distributed change in how prior knowledge, sensory evidence and the stable assumption of self-ownership are integrated.
Why body ownership needs priors
Your hand does not stop being yours every time the lights flicker, a sleeve reduces sensation or a video connection lags by 100 milliseconds.
A robust bodily self requires stability across noisy conditions. That stability implies that the system uses more than immediate sensory evidence. It carries expectations about continuity, anatomy, location and agency.
In Bayesian language, prior expectations and incoming likelihood information are combined. In ordinary language, the nervous system does not start from zero every time it has to decide whether a hand belongs to you.
Development and ageing can alter the relative reliability of these sources. The 2024 study is valuable because it makes that question empirical rather than philosophical.
The study extends rubber-hand logic without copying it
Classic rubber-hand experiments ask whether synchronous stroking can induce ownership over an artificial hand. This study instead used participants' own visually presented hand and manipulated delays across active movement and touch.
That changes the prior probability dramatically. An artificial hand begins as “not mine.” One's own hand begins with a strong lifetime history of ownership.
The experiment therefore examines how stable self-models tolerate temporary multisensory conflict rather than how easily an alien object can be incorporated.
Both paradigms belong to body-ownership science, but they probe different problems.
Lifespan research is more than comparing young and old
Many studies of ageing compare university-aged adults with one older group. A sample spanning childhood through late adulthood asks a better developmental question.
The body is not static between those endpoints. Limb proportions change. Motor skill changes. puberty changes body form and self-attention. Adult expertise stabilizes. Later life may bring changes in strength, sensation and movement. The internal model of “my body” has to remain coherent through all of it.
A lifespan design can reveal whether mechanisms shift gradually, change at particular periods or remain unexpectedly stable.
This study does not settle that developmental map, but it makes the map visible.
The result does not mean older adults are “more embodied”
A higher ownership rating is not a global score of embodiment.
It does not show better interoception, greater emotional awareness, wiser bodily judgment or stronger health. Body ownership is one component of bodily self-representation. Interoception concerns sensing internal physiological state. Proprioception concerns position and movement. Body image includes perceptual and evaluative representations. Agency concerns authorship of action.
These systems interact, but their measures are not interchangeable.
Calling an older participant “more embodied” because they maintained higher ownership ratings would collapse the very distinctions the experiment helps us make.
Mixed reality is a research instrument, not just a medium
The study also demonstrates why mixed reality matters scientifically. Digital mediation can alter timing, perspective, scale and visual form while preserving a controlled relationship to the participant's actual body.
This allows researchers to create conflicts that would be difficult or impossible in ordinary physical settings.
For human-technology research, this has a second relevance. Immersive systems are increasingly used in education, rehabilitation, training and entertainment. If age changes how bodily ownership responds to mediated sensorimotor information, design assumptions derived from young adult samples may not generalize.
The paper does not establish clinical design rules, but it identifies a variable designers should not pretend is constant.
Cross-sectional lifespan evidence has a built-in limit
The age pattern in this study is cross-sectional. Seven-year-olds were not followed until they became eighty. People of different ages were tested at one period in history.
That distinction matters because age differences can combine developmental change with cohort differences. Older adults grew up with different technologies, educational practices and sensory environments from younger participants. A cross-sectional curve can identify a robust age association without showing the within-person trajectory that produced it.
Longitudinal studies of body-ownership mechanisms would be difficult and expensive, but they would answer a different question: how does one person's sensory weighting change as their own body ages?
Until then, “with increasing age” should be read as an association across the sampled lifespan, not proof of a universal developmental law.
The task also reveals a general measurement principle
Body ownership is usually invisible because it is stable. Experimental science learns about the system by introducing controlled conflict. This is a wider lesson for human-capacity research.
Capacities often become measurable at their boundary conditions. Attention can be studied under distraction, judgment under uncertainty, emotion regulation under provocation, and body ownership under multisensory mismatch. The perturbation reveals how the system maintains coherence.
But boundary tasks should not be mistaken for ordinary life. The mixed-reality delays are tools for identifying mechanisms, not simulations of every real-world bodily experience. Ecological interpretation should preserve that distance.
What the evidence does not show
The study does not show that ageing improves body ownership in every setting. It does not show that older adults have superior bodily awareness. It does not show that top-down priors were directly measured or that one computational model uniquely explains the result. It does not show that all age-related sensory changes were absent, only that the measured visual dependence and proprioceptive acuity did not explain the observed ownership pattern. It does not establish how neurological disease, chronic pain or disability would alter the result.
The study also does not show that body ownership is culturally invariant. Its sample and laboratory paradigm cannot stand in for every population or every kind of bodily experience.
Institute synthesis: stability is an achievement, not the absence of change
The Institute uses adaptive self-continuity as a synthesis phrase for a capacity visible in this literature: maintaining a coherent bodily self while the evidence about the body changes.
This is Institute synthesis, not a construct named or validated by Weijs and colleagues.
The phrase matters because human development is often described as adding sensitivity. The lifespan body-ownership literature suggests another capacity: deciding what not to update from every transient discrepancy.
A system that revised ownership with every delayed frame would be exquisitely sensitive and functionally chaotic.
A robust self must be both revisable and resistant to noise.
Why this matters for Inner Technology
Inner Technology should not equate self-awareness with maximal responsiveness to every signal.
Sometimes capacity means detecting change. Sometimes it means preserving continuity despite change. The science of body ownership gives us a concrete example of that balance.
When technologies mediate bodies through avatars, telepresence or augmented reality, the relevant human question is not only whether a system feels immersive. It is which sensory contingencies support ownership, which conflicts disturb it, how those thresholds vary across people, and what prior expectations users bring with them.
The bodily self is constructed continuously, but not arbitrarily.
The more useful language is not “the body knows who it is.” It is that the nervous system integrates evidence about selfhood across time, and the rules of that integration can change with age.
Research references
- Weijs ML, Roel Lesur M, Daum MM, Lenggenhager B. Keeping up with ourselves: Multimodal processes underlying body ownership across the lifespan. Cortex. 2024;177:209-223. DOI: 10.1016/j.cortex.2024.05.013. https://pubmed.ncbi.nlm.nih.gov/38875735/
- Botvinick M, Cohen J. Rubber hands 'feel' touch that eyes see. Nature. 1998;391:756. DOI: 10.1038/35784.
- Tsakiris M, Haggard P. The rubber hand illusion revisited. J Exp Psychol Hum Percept Perform. 2005;31:80-91. DOI: 10.1037/0096-1523.31.1.80.