Two Paths Upward: MacMillan's Spiral and Staircase Models™ of Psychosocial Development

Every person reading this is on a developmental journey. It began before you could speak and it will continue for as long as you live. You have been moving through Erikson's stages whether you knew their names or not, building trust or struggling to, finding your identity or searching for it, reaching toward intimacy or aching in its absence. The journey is universal (Erikson, 1963, 1980).

The path is not.

This post is about two paths. Not a right path and a lesser one. Not a default and a variation. Two genuinely different routes through the same human territory, each with its own logic, its own rhythm, its own beauty, and its own particular vulnerability. One moves in a spiral. One moves in a staircase. And understanding both, with equal depth and equal respect, is what this framework asks of us.

How Each Path Receives the World

Development does not happen inside a person. It happens between a person and their environment. The feedback that flows between the two is what makes growth possible, and the first place the spiral and the staircase diverge is in how that feedback arrives (Kegan, 1982).

For non-autistic people, feedback is largely continuous, embodied, and immediate. Body empathy, the combination of embodied simulation and interoceptive sensitivity, means that the non-autistic nervous system is registering social information in real time (Craig, 2009; Gallese, 2007). A shift in someone's expression, a change in the energy of a room, a subtle signal of warmth or withdrawal: these land in the non-autistic body as felt data, processed largely below the level of conscious awareness. The non-autistic person does not decide to receive this feedback. It arrives. It is structural, neurological, constant. In every interaction, the spiral is being fed.

For autistic people, this continuous embodied stream is not the primary channel. The autistic nervous system is not tuned to the same frequency of immediate social feedback, and this is not a failure. It is a different neurological architecture, one that brings its own profound capacities and attends to the world in its own way. But it means that the feedback loop driving development operates differently. Autistic people learn about their social environments more through explicit observation, through pattern recognition, through the deliberate construction of understanding over time (Milton, 2012). Where the spiral is continuously fed, the staircase is fed in a different rhythm: more concentrated, more sequential, requiring more intentional conditions to function well.

Both pathways are receiving the world. They are receiving it through different instruments. And what each instrument picks up shapes the path that follows.

The Shape of Forward Movement

Watch the spiral move. It curves outward and upward, then bends back toward itself, then rises again. The non-autistic developmental journey follows this arc. There are periods of forward movement, of confidence, of applying what is known, of feeling adequate to the situation. Piaget called this assimilation: the world is being taken in and organized within existing understanding (Piaget, 1952). Baumrind would recognize it as the responsiveness phase: the person is meeting the environment and being met in return (Baumrind, 1991).

And then the spiral curves back. Something in the embodied feedback loop registers a mismatch: a response that didn't land as expected, a perspective that doesn't fit the current self-concept, a challenge that the existing understanding cannot absorb without changing. This is accommodation in Piaget's language, demandingness in Baumrind's (Baumrind, 1991; Piaget, 1952). The non-autistic person pauses, reorganizes, integrates the new information into a slightly revised understanding of self and world. The pause is not failure. It is the mechanism of growth. And then the spiral rises again, a little higher than before.

This oscillation, outward and back, outward and back, is not weakness or inconsistency. It is the engine running exactly as it should. The emotional texture of the oscillation can be uncomfortable: moments of self-doubt, of uncertainty, of feeling temporarily less sure of oneself. But the body empathy feedback loop is always running, always recalibrating, always pulling the spiral back into forward movement. The non-autistic developmental journey is characterized by this continuous, looping, self-correcting motion upward.

Now watch the staircase. It moves differently. There is a vertical rise, then a horizontal surface, then another vertical rise. The autistic developmental journey has its own distinct rhythm: a period of concentrated learning, of taking in something genuinely new, followed by a period of application, of moving along the flat surface of a stair, consolidating what has been learned and practicing its use in the world. Then another vertical rise. Then another horizontal surface.

The staircase is more sequential and more paced than the spiral. It is structured differently. The vertical moments, the concentrated learning, require the right conditions: clear information, explicit feedback, a environment that offers what the autistic nervous system can actually receive and use. When those conditions are present, the staircase rises. When they are absent, the horizontal surface can extend. Not because the autistic person has stopped developing, but because the fuel the staircase runs on has not been adequately supplied.

Where the spiral self-corrects through continuous embodied feedback, the staircase depends more on the quality and clarity of the environment around it. This is not a deficit of the staircase. It is its nature. And it places a responsibility on environments, on families, on schools, on relationships, on clinical practice, that has not yet been adequately understood or met.

What It Feels Like From the Inside

These are not just structural differences. They are lived differences, and they shape how development is experienced from the inside in ways that matter for how we understand ourselves and each other.

The non-autistic experience of development is often characterized by a felt sense of social embeddedness. Because the body empathy feedback loop is continuous, non-autistic people are rarely entirely alone in their sense of self. They are always, to some extent, in felt contact with the social world around them, always receiving information about how they are being received, always in the process of integrating that information into who they understand themselves to be. This can be rich and connecting. It can also be destabilizing: the non-autistic sense of self is genuinely responsive to the social environment, and in environments that offer distorted or hostile feedback, that responsiveness becomes a vulnerability.

The autistic experience of development has a different interior quality. There is often a strong and consistent relationship with one's own perspective, a clarity about one's own inner world, a groundedness in one's own experience that does not depend on continuous social calibration. This is a real strength. It is also the source of some of the most significant challenges autistic people face in a world that frequently misreads their social presentation and offers feedback shaped by that misreading rather than by accurate perception of who the autistic person actually is. Sasson and colleagues found that non-autistic observers form negative first impressions of autistic people within seconds, based on social presentation style rather than the content of what autistic people actually say or do (Sasson et al., 2017). The autistic person on the staircase is navigating an environment that is often sending back inaccurate information, and doing so with a feedback mechanism that, by its nature, requires more explicit and intentional input to function well. That is a significant weight to carry through a developmental journey.

Both experiences contain gifts. Both contain vulnerabilities. But it would be dishonest to pretend the vulnerabilities are evenly distributed. The non-autistic spiral carries a built-in adaptability, a continuous capacity to read what a situation requires and adjust in real time. The staircase does not have that same structural resilience. What the spiral absorbs and moves past, the staircase may meet as a genuine obstacle. And when obstacles have accumulated in a particular domain of life, the wariness that follows is not weakness. It is an accurate and reasonable response to lived experience.

What Can Interrupt the Upward Movement

Csikszentmihalyi's flow research identified the two conditions that pull people out of the channel of optimal development: too much challenge, which produces overwhelm and anxiety, and too little challenge, which produces stagnation (Csikszentmihalyi, 1990). Both interrupt growth. Both can affect spiral and staircase alike, though they tend to arrive through different doors.

For the non-autistic spiral, the most significant interruptions often come through the feedback loop itself. When the social environment consistently offers distorted feedback, when the people around a non-autistic person are not providing the mutual reflection that the spiral depends on, the oscillation can become dysregulated. The spiral may contract, the person becoming overly dependent on external validation, unable to find the self-correcting momentum that healthy oscillation provides. In neurodiverse relational environments, where a non-autistic person spends extended time without the mutual body empathy reflection they depend on, the spiral can lose some of its natural self-correction. The person may find their own perspective becoming harder to locate, absorbed into the stronger gravitational field of a perspective that does not reflect back.

For the autistic staircase, the most significant interruptions come when the environment fails to provide the explicit, clear, appropriately calibrated feedback that the staircase runs on. When the feedback is absent, the horizontal surface of a stair extends indefinitely and the next vertical rise never comes. When the feedback is present but inaccurate, shaped by neurotype bias rather than genuine understanding, the staircase receives bad information and may build in the wrong direction. And when the environment demands that the autistic person learn through the non-autistic feedback channel, through embodied social osmosis rather than explicit and sequential input, it is asking the staircase to become a spiral. It cannot. And the asking itself is a harm (Milton, 2012).

Hull and colleagues, and Cage and Troxell-Whitman, documented what happens when autistic people are required to perform non-autistic social patterns in order to be accepted: camouflaging, the effortful construction of a social mask, carries significant mental health costs (Cage & Troxell-Whitman, 2019; Hull et al., 2017). The staircase, when asked to pretend to be a spiral, does not rise. It exhausts itself in the performance.

The Same Destination, Two Dignified Routes

And yet. Despite different feedback mechanisms, different movement patterns, different interior experiences, different vulnerabilities: both paths are headed to the same place.

Trust. Autonomy. Initiative. Identity. Intimacy. Generativity. Integrity.

These are Erik Erikson's eight destinations of psychosocial development, mapped across the full arc of a human life (Erikson, 1963, 1980). They are not achievements reserved for one neurotype. They are the shared destinations of every human developmental journey, the qualities that allow a person to feel that their life belongs to them and that they belong to the world.

Scheeren and colleagues followed more than nine hundred autistic adults across six years and found that psychosocial functioning and wellbeing both improved over time (Scheeren et al., 2022). The staircase rises. Autistic adults grow. The developmental journey does not end at adolescence or at diagnosis. It continues, across the lifespan, for autistic and non-autistic people alike.

What has been missing is not the capacity for growth. What has been missing is the framework that takes both paths seriously, that builds environments calibrated to what each path actually needs, and that stops asking the staircase to be a spiral and the spiral to be a staircase.

MacMillan's Spiral and Staircase Model™ does not ask either path to become the other. It asks us to understand both, to honor both, and to build the holding environments that allow both to rise (Kegan, 1982).

Because the destination is the same. And everyone deserves to reach it.

Next in this series: The Holding Environment, what optimal development actually requires for each neurotype, and what it looks like to build conditions where both the spiral and the staircase can rise.

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

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