These days the word “retarded” is a simple term of abuse. Not so long ago it was a relatively “politically correct” term for intellectual disability, which replaced another set of nominally scientific categorisations, which themselves had become terms of abuse: idiot, imbecile, moron. These terms of course persist to this day as acceptable language, rather than ableist slurs, perhaps because of the way they became detached from the scientific framework in which they were once used. But we are not as far from that world as we might like to think. Those categorisations were connected both to the notion of IQ and to that of mental age: an idiot was a person whose intelligence never surpassed that of a typical 2 year old child; for an imbecile the relevant age was 7; for a moron it was 12. A product of the era of eugenics, though related to a temporal measure these concepts were supposed to identify something fixed about the innate capacities of the individual.

The direct temporal reference in the term “retarded” had the benefit of shifting things from the more apparently essentialising mode of the earlier categorisations: one could be born an “idiot”, and that was that. Retardation was at least specified only in terms of change over time: it was a question of when one achieved certain milestones of development. If these came late relative to a certain norm, then one was classified as retarded.

Intellectual disability is still conceived largely in the same terms, except the term tainted by its association with playground abuse has been dropped in favour of a synonym: developmental delay. This shift has the virtue of a further step away from an essentialising mode of categorisation. “Retarded” could be a term of abuse because that was supposed to be something that one was; worse, it could be nominalised: a retard. There is no such nominalisation for developmental delay: one can be delayed, in the same way that one can be late to a party; that’s about as far as it seems to get, though one can’t rule out the possibility that the linguistic innovation of the playground will find some way of turning it into an insult. But the fact that there is no longer an associated term of abuse does not imply that the current framework is entirely lacking in the negative implications of “retard”, “moron”, “idiot” and “imbecile”.

This is how “developmental delay” works: most children develop their core capacities in a fairly orderly fashion, since it is obvious that one must be able to support one’s head with one’s neck before one can sit up; that one must be able to support oneself on one’s arms before one can get onto hands and knees; that one must be able to get on hands and knees before one can crawl; that one must be able to feel and coordinate the muscles in one’s hands before one can play. There is thus a set of things that a typically developing child will achieve in a rough series, sometimes with a little variation in the exact ordering, since development proceeds on many dimensions at once. Statistically, children will tend to advance along this series at a certain pace. The state makes some tokenistic efforts to keep track of the health of its infant citizens by measuring them against these temporal norms at certain points. If you fall short of the norms, then you are categorised as “delayed”.

The notion of developmental delay is still related to one of those other temporal classifications with roots in eugenics: mental age theory. As with idiot, imbecile and moron, but still nominally acceptable to this day, this is the well-known idea that a person can have a “mental age” that differs from their actual chronological age. In special needs circles sometimes one encounters parents who say things like “my daughter is 20 but has the mental age of 12”. Some people with intellectual disabilities have objected to mental age theory for the way that it infantilises them: a 20 year old with an intellectual disability is in actuality highly unlikely to be much like a 12 year old; they are much more likely to be like a 20 year old with difficulties doing specific kinds of things.

Something similar applies to developmental delay. Most professionals have to categorise in order to be able to treat, but these categorisations can become serious obstacles to seeing the person in front of them. A speech therapist may encounter a 3 year old who will not speak in sessions, and refuses to engage with the therapist. The child may then be conceptualised as essentially akin to a baby on the level of speech and communication, regardless of what they do and how they behave in the rest of their life. The 3 year old, who has all the complex emotions and social connections of a toddler, is cut down to the equivalent of a baby just like that, because they wouldn’t engage in a certain kind of activity. This then shapes the therapeutic approach: we end up acting as though we need to develop the first glimmers of “communicative intent”, “shared attention” and so on in a child who may well wonder why people are suddenly acting so strangely towards them. This in turn can lead to perverse effects: a toddler treated like a baby is probably not going to learn in the way a toddler typically would; if they learn anything at all at such moments, it is that the world sees them as lacking in autonomy and intelligence in a way that is comparable to a newborn. Thus the categorisation risks creating what it is supposed to diagnose.

The problem is that people do not actually develop according to the schemas that paediatricians have generalised from the statistical norm: even for typically developing children, “milestones” capture just momentary snapshots in a complex organic process. With typically developing children this doesn’t really matter, since that process will go on anyway. But when we turn these milestones around and make them into the basis of a classificatory system which affects the way we treat children, they can become one of the ways in which a society produces disability unwittingly even while trying to treat it. As some of the more interesting psychologists of the early 20th century, such as Adler and Vygotsky, recognised, a person who has a disability or difficulty in one way is not just a person with that lack, since there are manifold complex processes of compensation and adjustment that occur in the development of a personality. These are mediated socially, by institutions and the behaviours of other people. And for this reason, that social mediation is all-important. It can be both a level on which conditions can be substantially improved, and one which magnifies and worsens some “primary” condition.