The Gap: Why Developmental Psychology Has Never Fully Accounted for Autism

There is a story developmental psychology has been telling for decades. It goes like this: human beings move through predictable stages of growth, from the trust of infancy through the identity-seeking of adolescence and into the intimacy, generativity, and integrity of adult life. Erik Erikson gave us this map in the middle of the twentieth century, and it remains one of the most widely used frameworks in psychology, education, and clinical practice (Erikson, 1963, 1980). It is a good map. It describes something real.

What it does not describe is what happens when the person moving through those stages has an autistic brain.

That gap has cost us something. Not in the abstract, but in the lives of real people who arrived at adulthood without a clear sense of who they were, who struggled to build close relationships without understanding why closeness felt so complicated, who sensed that the developmental scaffolding everyone around them seemed to be climbing was simply not built for them. The map existed. They just couldn't find themselves on it.

A Framework Built for One Neurotype

Erikson was not thinking about autism when he developed his stages of psychosocial development. Neither were Piaget, Baumrind, or most of the developmental theorists who followed them. This is not a criticism. Although autism was first described during Erikson’s lifetime, it was not formally recognized in the DSM as its own diagnostic category until decades after his core developmental framework had already taken shape. And even then, what understanding existed was filtered almost entirely through a deficit lens: autism as disorder, as deviation, as a failure to meet non-autistic developmental norms.

The result is that the entire edifice of developmental psychology, its stages, its milestones, its models of how human beings grow into themselves and into relationship with others, was constructed with the non-autistic nervous system as its invisible default. When autistic people were considered at all, it was usually to note where they fell short of the model, not to ask whether a different model might be needed.

Damian Milton named something important in 2012 when he introduced the double empathy problem. His argument, now supported by a substantial body of empirical research, is that the communication difficulties observed between autistic and non-autistic people are not a one-way failure of autistic social cognition. They are a mutual mismatch between two differently disposed social actors. Autistic people are not simply failing to understand non-autistic social reality. Non-autistic people are equally failing to understand autistic social reality. The problem is relational, not located entirely within the autistic person (Milton, 2012; Milton et al., 2022).

Ten years later, Milton, Gurbuz, and López returned to this argument and made its developmental implications explicit. What is needed, they wrote, is an alternative account of autistic development: one not rooted in the idea of social communication disorder, but in the recognition of a different embodied way of being in the world that shapes social interaction and understanding differently (Milton et al., 2022).

That call has been sitting in the literature. MacMillan's Spiral and Staircase Model™ answers it.

What the Research Has Been Telling Us

In the years since Milton's original paper, empirical research has been quietly assembling a picture that developmental theory has not yet fully organized. A few findings are worth sitting with before the theory itself is introduced.

Crompton and colleagues found in 2020 that autistic people share information effectively with other autistic people, and that information transfer degrades more in mixed neurotype interactions than in same-neurotype ones. Rapport is also lower in mixed-neurotype interactions (Crompton, Ropar, et al., 2020; Crompton, Sharp, et al., 2020). This is not a story about autistic deficit. It is a story about fit between a social actor and the environment providing them feedback.

Sasson and colleagues found in 2017 that non-autistic observers form less favorable first impressions of autistic people within seconds, based on social presentation style rather than the content of what autistic people actually say (Sasson et al., 2017). The bias is immediate, embodied, and largely outside conscious awareness. What this means developmentally is significant: autistic people are not merely receiving less social feedback than non-autistic people in non-autistic environments. They are often receiving actively distorted feedback, feedback shaped by implicit neurotype bias rather than accurate perception of who the autistic person actually is.

Scheeren and colleagues conducted a six-year longitudinal study of more than nine hundred autistic adults and found that psychosocial functioning and wellbeing both improved over time (Scheeren et al., 2022). Autistic adults grow. Autistic development continues across the lifespan. The staircase moves upward.

And Lerner and colleagues, asking autistic adults and caregivers directly what had helped or harmed their development, found that relational support from other people was identified more frequently than any specific service or intervention (Lerner et al., 2025). Development, for autistic people as for everyone, happens in relationship and in environment.

Taken together, these findings point toward something the field has not yet given a coherent name: autistic people follow a developmental pathway that is shaped by different feedback mechanisms, different social environments, and different neurological foundations than non-autistic people, and that pathway needs its own framework if we are going to support it well.

The Cost of the Gap

What happens when a developmental framework does not account for an entire neurotype? The consequences are not merely theoretical.

Autistic people arrive at adulthood in significant numbers without having successfully navigated Erikson's stage of identity formation. Not because identity formation is impossible for autistic people, but because the environments and feedback loops that support identity formation in non-autistic development were not designed with autistic neurology in mind, and no one built an alternative. Research by Davies and colleagues and by Cooper and colleagues confirms what many autistic adults already know: positive autistic identity is strongly tied to acceptance and support from the surrounding environment, and it is powerfully connected to mental health and wellbeing (Cooper et al., 2023; Davies et al., 2024). Identity is not simply an internal achievement. It is something that happens between a person and their world.

The same is true of intimacy. Grace and colleagues found that loneliness in autistic adults is widespread and is associated not only with autistic characteristics but with the absence of understanding and acceptance, the weight of camouflaging, and the accumulated exhaustion of navigating environments built for a different kind of mind (Grace et al., 2022). Autistic adults want connection. They want what Erikson's framework promises: intimacy, generativity, a life that feels like it belongs to them. The framework simply never told them how to get there.

Toward a New Framework

Ommensen and colleagues, writing in 2026, argue explicitly for lifespan developmental psychology as the right lens for understanding autistic experience, precisely because it accounts for different developmental trajectories across the lifespan and for the influence of environment and context on those trajectories (Ommensen et al., 2026). The argument is straightforward: autism is not a childhood condition that resolves or stabilizes. It is a lifelong neurological difference that shapes development at every stage, and our frameworks need to reflect that.

MacMillan's Spiral and Staircase Model™ is a response to exactly this need. It does not replace Erikson's stages. It uses them as a destination: trust, autonomy, initiative, identity, intimacy, generativity, integrity (Erikson, 1963, 1980). These are the qualities that matter, for autistic and non-autistic people alike. What the model proposes is that the pathways toward those qualities look structurally different depending on neurology, and that understanding those differences is the first step toward building environments that actually support all people in getting there.

The non-autistic pathway is a spiral. The autistic pathway is a staircase. Both move upward. Neither is a lesser version of the other. They are different routes through the same human project of becoming.

The next post in this series introduces MacMillan's Spiral Model of Non-Autistic Development™: what the spiral looks like, what drives it, and why understanding it is essential to understanding what the staircase is doing differently.

This post is part of an ongoing series on MacMillan's Spiral and Staircase Model™ of psychosocial development across neurologies:

Post 1. The Gap: Why Developmental Psychology has Never Fully Accounted for Autism
Post 2. The Engine of Development: What Growth Requires Across all Neurologies
Post 3. Two Paths Upward: MacMillan's Spiral and Staircase Models of Psychosocial Development
Post 4. The Holding Environment: What Development Actually Requires
Post 5. The Destination is the Same: Erikson's Full Arc Across Neurologies


References

Cooper, K., Smith, L. G. E., & Russell, A. J. (2023). The impact of a positive autism identity and autistic community solidarity on social anxiety and mental health in autistic young people. Autism, 27(3), 848–857. https://doi.org/10.1177/13623613221118351

Crompton, C. J., Ropar, D., Evans-Williams, C. V. M., Flynn, E. G., & Fletcher-Watson, S. (2020). Autistic peer-to-peer information transfer is highly effective. Autism, 24(7), 1704–1712. https://doi.org/10.1177/1362361320919286

Crompton, C. J., Sharp, M., Axbey, H., Fletcher-Watson, S., Flynn, E. G., & Ropar, D. (2020). Neurotype-matching, but not being autistic, influences self and observer ratings of interpersonal rapport. Frontiers in Psychology, 11, Article 586171. https://doi.org/10.3389/fpsyg.2020.586171

Davies, J., Cooper, K., Killick, E., Sam, E., Healy, M., Thompson, G., Mandy, W., Redmayne, B., & Crane, L. (2024). Autistic identity: A systematic review of quantitative research. Autism Research, 17(5), 874–897. https://doi.org/10.1002/aur.3105

Erikson, E. H. (1963). Childhood and society (2nd ed.). W. W. Norton.

Erikson, E. H. (1980). Identity and the life cycle. W. W. Norton.

Grace, K., Remington, A., Lloyd-Evans, B., Davies, J., & Crane, L. (2022). Loneliness in autistic adults: A systematic review. Autism, 26(8), 2117–2135. https://doi.org/10.1177/13623613221077721

Lerner, J. E., Schiltz, H., Schisterman, N., Ziegler, S., & Lord, C. (2025). What factors have been the most helpful and harmful and when? Identifying key impacts on psychosocial development according to autistic adults and caregivers. Journal of Autism and Developmental Disorders. https://doi.org/10.1007/s10803-025-06800-4

Milton, D. E. M. (2012). On the ontological status of autism: The “double empathy problem.” Disability & Society, 27(6), 883–887. https://doi.org/10.1080/09687599.2012.710008

Milton, D., Gurbuz, E., & López, B. (2022). The “double empathy problem”: Ten years on. Autism, 26(8), 1901–1903. https://doi.org/10.1177/13623613221129123

Ommensen, B., Attwood, T., Pachana, N. A., & Sofronoff, K. (2026). The potential for successful autistic ageing: Proposing a lifespan developmental psychology approach. Autism. https://doi.org/10.1177/13623613261418468

Sasson, N. J., Faso, D. J., Nugent, J., Lovell, S., Kennedy, D. P., & Grossman, R. B. (2017). Neurotypical peers are less willing to interact with those with autism based on thin slice judgments. Scientific Reports, 7, Article 40700. https://doi.org/10.1038/srep40700

Scheeren, A. M., Buil, J. M., Howlin, P., Bartels, M., & Begeer, S. (2022). Objective and subjective psychosocial outcomes in adults with autism spectrum disorder: A 6-year longitudinal study. Autism, 26(1), 243–255. https://doi.org/10.1177/13623613211027673