The Boundary Gap
What Developmental Psychology Has Never Quite Named
There is a word that appears everywhere in conversations about autistic experience and almost nowhere in the developmental psychology literature on autism as a coherent construct. That word is boundaries.
Clinicians use it. Autistic people use it. The people in relationship with autistic people use it, sometimes with frustration, sometimes with grief, sometimes with the particular exhaustion of someone who has been trying to explain something important and cannot find the language that makes it land. Boundaries are too rigid, or too porous, or absent in ways that are confusing and painful for everyone involved. The word is everywhere. The framework is not.
That is not an accident. It is a gap, and it is a gap with consequences. When the developmental psychology literature does not organize the territory that the word boundaries is trying to describe, clinicians and autistic people and their families are left navigating that territory without a map. They feel the problem. They live inside the problem. But they do not have the conceptual tools to understand what is actually happening, why it is happening, and what the pathway forward looks like (Bottema-Beutel et al., 2021; Leadbitter et al., 2021).
This series is an attempt to build those tools. Not by inventing something new, but by bringing together what the research has actually been saying, often under different names, and organizing it into a framework that is useful for the people who need it most.
What the Research Has Been Calling It
The developmental psychology literature has not been ignoring the territory that boundaries describes. It has been mapping it under a different set of names: autonomy, self-determination, agency, consent, self-advocacy (Deci & Ryan, 2000; Ryan & Deci, 2017; Shogren et al., 2021; Thompson-Hodgetts et al., 2023). These are the words the research uses when it is describing what happens when a person knows they have a self that is allowed to choose, that is allowed to act, that is allowed to say no, that is allowed to take up space in the world without requiring permission for every expression of its own nature.
That is what boundaries are. Not a social skill. Not a communication strategy. Not a set of rules to be memorized and applied. Boundaries are the lived relational expression of a developmental achievement: the felt sense of where the self ends and another person begins, and the capacity to act from that sense with enough confidence that the self does not have to disappear in order for the relationship to continue (Deci & Ryan, 2000; Erikson, 1963, 1980; Ryan & Deci, 2017).
The research on autistic autonomy, self-determination, and self-advocacy is substantial and growing. It tells us that autistic people benefit enormously from environments that support autonomous functioning, that respect autistic ways of choosing and communicating and acting, and that measure competence through developmentally appropriate and neurologically accurate channels rather than through the lens of how closely autistic behavior approximates non-autistic norms (Leadbitter et al., 2021; Ryan et al., 2024; Thompson-Hodgetts et al., 2023; Tomaszewski et al., 2021, 2022). It tells us that self-advocacy and self-determination are strongly connected to adjustment outcomes across education, employment, relationships, identity, and quality of life (Martino et al., 2025; Shogren et al., 2021; Tomaszewski et al., 2021, 2022). And it tells us, implicitly, that when those conditions are not present, something developmental is at stake, not just something behavioral.
What the literature has not done is pull those threads together under the word that the people living this experience actually use. That is the gap this series is filling. Boundaries, understood developmentally, is the concept that organizes autonomy, self-determination, consent, self-advocacy, and agency into a single coherent framework, one that can be understood across the lifespan, across neurologies, and across the different kinds of relationships in which boundary dynamics play out (Deci & Ryan, 2000; Erikson, 1963, 1980; Ryan & Deci, 2017).
What Erikson Knew
Erik Erikson placed autonomy at the very beginning of the developmental map, immediately after trust, and for a reason that matters deeply for everything that follows (Erikson, 1963, 1980). The infant who has built enough trust to begin exploring the world now faces a new developmental question, one that will echo forward through every subsequent stage of life: do I have a self that is allowed to choose?
The toddler who is allowed to choose, within safe limits, who is supported in the expression of their own will even when that will is inconvenient or messy or different from what the adults around them prefer, is building something that goes far beyond table manners and toilet training. They are building the developmental foundation of boundaries. The felt sense that the self is real, that it has edges, that those edges are legitimate, and that acting from within those edges is not defiance but personhood (Deci & Ryan, 2000; Erikson, 1963; Ryan & Deci, 2017).
When that experience is consistently denied, when the child's will is overridden, corrected, shamed, or simply not recognized as a will worth reckoning with, Erikson named what develops in its place: shame and doubt (Erikson, 1963, 1980). Not just as feelings, but as developmental orientations, ways of relating to the self and the world that persist long after the toddler years and shape every subsequent encounter with the question of whether the self is allowed to take up space.
Erikson's next two stages deepen the stakes. Initiative, his third stage, asks: can I act from myself, reach outward, try things, without being stopped or shamed for the reaching? Industry, his fourth stage, asks: can I build something, develop competence, find my own way of contributing, without being measured only against standards I was not built to meet? Each of these stages is, in its own way, a boundary question. Each of them asks whether the self is allowed to be itself in the world, and each of them is shaped profoundly by whether the environment answers yes (Erikson, 1963, 1980; Shogren et al., 2021; Tomaszewski et al., 2021, 2022).
Two Different Pathways to the Same Destination
MacMillan's Spiral and Staircase Model™ gives us the framework for understanding why the developmental pathway toward healthy boundaries looks structurally different across neurologies, even when the destination, Erikson's autonomy, initiative, and industry, is the same for everyone.
For people whose development follows the non-autistic pathway, the felt sense of where the self ends and another person begins is built partly through the same continuous embodied feedback loop that characterizes all non-autistic social development. The non-autistic nervous system navigates the social world through what MacMillan terms body empathy, that immediate, embodied, largely automatic reception of social information from the faces and bodies of others, grounded in high levels of embodied simulation and interoceptive sensitivity and awareness (Craig, 2009; Gallese, 2007). This capacity means that the non-autistic person is continuously registering, in real time and largely below conscious awareness, not only what others are feeling but where others are in relation to the self. The social and emotional boundaries between self and other are felt as much as they are thought, and they are felt constantly, updating with every interaction (Craig, 2009; Gallese, 2007).
This continuous embodied registration is what allows the non-autistic developmental pathway to build a felt sense of boundaries through the natural oscillation of the spiral: the forward movement of assimilation, taking in new social information and integrating it into an existing understanding of self and other, followed by the accommodation of reorganization when that information doesn't fit, when a boundary has been crossed and the self has to recalibrate where it stands (Piaget, 1952). The spiral self-corrects. It receives feedback through the body and adjusts. And over time, through thousands of these small cycles, a robust and flexible sense of where the self ends and the other begins takes shape.
For people whose development follows the autistic pathway, the process is different from the ground up. Without the same immediate, automatic reception of embodied social information that the non-autistic pathway runs on, the autistic person builds their understanding of the social world, including their understanding of where the self ends and another begins, more sequentially, more deliberately, and more dependently on explicit environmental feedback (Jaswal & Akhtar, 2019; Milton, 2012; Thompson-Hodgetts et al., 2023). The felt sense of boundaries that the non-autistic pathway acquires more or less continuously through ambient social experience is something the autistic pathway has to construct more carefully, more intentionally, and under conditions that the environment has rarely been designed to provide (Ryan et al., 2024; Shogren et al., 2021; Thompson-Hodgetts et al., 2023).
This is not a deficit. It is a different architecture, one that brings its own genuine capacities and its own ways of knowing the social world (Bottema-Beutel et al., 2021; Jaswal & Akhtar, 2019; Milton, 2012). But it means that the autistic developmental pathway toward healthy boundaries is more vulnerable to disruption when the environment fails to provide the clear, accurate, and calibrated feedback it depends on (Dieleman et al., 2019; Ryan et al., 2024; Thompson-Hodgetts et al., 2023). And as we will see across this series, the environments that autistic people have typically moved through have failed to provide that feedback in ways that are not incidental but structural (Leadbitter et al., 2021; Pearson & Rose, 2021; Zhuang et al., 2023).
Why the Different Perceptions of the Social World Matter for Boundaries
Understanding why the boundary pathways diverge requires sitting with the foundational difference between how autistic and non-autistic people perceive and navigate the social world, because that difference is not only relevant to communication and social interaction. It is the mechanism that explains the boundary experience from the inside (Craig, 2009; Gallese, 2007; Milton, 2012).
Non-autistic people move through the social world in continuous felt contact with the perspectives of others. Body empathy means that a non-autistic person is registering, in their own body, something of what the people around them are experiencing: their comfort, their discomfort, their approval, their withdrawal (Craig, 2009; Gallese, 2007). This continuous registration creates a kind of automatic social calibration, a real-time sense of how one's own actions are landing and what adjustments might be needed. And critically for boundaries, it creates a continuous felt sense of the difference between self and other, between what is inside the self and what belongs to someone else.
Autistic people navigate the social world differently. Without the immediacy of body empathy, the understanding of others' perspectives, of where others stand in relation to the self, is built more sequentially and more deliberately. It requires more time, more explicit information, and more intentional processing (Jaswal & Akhtar, 2019; Milton, 2012). This is not a lesser way of navigating the social world. It is a different way, one that can produce great depth of understanding and precision of observation (Bottema-Beutel et al., 2021; Jaswal & Akhtar, 2019). But it means that the automatic, continuous calibration of self against other that the non-autistic pathway takes for granted is not structurally available in the same form, and that the boundary sense that calibration supports has to be built through different means (Ryan et al., 2024; Shogren et al., 2021; Thompson-Hodgetts et al., 2023).
The developmental implication is direct. When two people whose pathways differ in this fundamental way are in relationship with each other, whether as parent and child, as siblings, as friends, or as intimate partners, the boundary experience of each person is being shaped by a different architecture. Each person's sense of where the self ends is being constructed through different channels, maintained through different feedback loops, and made vulnerable by different kinds of disruption (Deci & Ryan, 2000; Erikson, 1963, 1980; Ryan & Deci, 2017). Understanding that difference is the beginning of understanding why boundary dynamics in neurodiverse relationships are so consistently difficult, and why addressing them requires more than communication tips (Milton, 2012; Thompson-Hodgetts et al., 2023).
What This Series Will Do
The developmental gap this series is addressing is not simply an oversight in the literature. It is the consequence of a larger failure: the failure to build a coherent framework for autistic development that takes the autistic developmental pathway seriously on its own terms, rather than measuring it against the non-autistic pathway and cataloguing the ways it falls short (Bottema-Beutel et al., 2021; Leadbitter et al., 2021).
MacMillan's Spiral and Staircase Model™ is that framework. And boundaries, understood as the lived relational expression of Erikson's autonomy, initiative, and industry, as the felt sense of where the self ends and another begins, and as the developmental achievement that makes genuine selfhood in relationship possible, is one of the most consequential territories that framework needs to map (Erikson, 1963, 1980; Ryan & Deci, 2017; Thompson-Hodgetts et al., 2023).
The posts that follow will trace that mapping across the developmental lifespan. How the autistic experience of autonomy, initiative, and industry is shaped by environments that correct, redirect, and override. How masking and burnout are, at their core, boundary phenomena (Mantzalas et al., 2022; Pearson & Rose, 2021; Zhuang et al., 2023). And what it looks like when autistic and non-autistic boundary architectures meet each other in close relationship, and what genuine mutual respect for both requires.
The goal, as always, is the same destination for everyone: a self that knows where it stands, that is allowed to choose, and that can be in relationship with others without disappearing in the process (Deci & Ryan, 2000; Erikson, 1963, 1980; Ryan & Deci, 2017).
Next in this series: When the Self Is Not Allowed to Choose, how the autistic experience of autonomy, initiative, and industry is shaped by environments that correct, redirect, and over-support, and what that accumulation costs developmentally.
This was Article 1: The Boundary Gap
This is Series III — Boundaries Across Neurologies: Autistic Development, High Body Empathy, and Neurodiverse Relationships
Articles in the Series:
The Boundary Gap
What Developmental Psychology Has Never Quite NamedWhen the Self Is Not Allowed to Choose
Over-Control and the Autistic Developmental PathwayWhen the Self Is Never Challenged
Over-Support and the Limits of Unconditional AccommodationNarcissistic Behaviors, Autistic Development, and the Optimal Environment
A Theoretical Framework for Future ResearchMasking as Boundary Collapse
What Happens When the Self Learns to Override ItselfThe Other Side of the Boundary
How the Same Developmental Gap Produces Two Problems at OnceThe Other Architecture
High Body Empathy, Boundary Vulnerability, and the Non-Autistic Developmental PathwayBoundaries in Neurodiverse Relationships
When Two Architectures Meet
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