J Health Behav Med Hist 2026-5
The Behavioural Organ. A relational executive system for the design and execution of human behaviour
Robert C. van de Graaf, Performance Medicine Specialist, Director
MEDTCC Institute for Health, Behaviour, Medicine and its History, and Perform Health Clinic ,The Netherlands
Peter F. van de Graaf, Health Performance Coach
MEDTCC Institute for Health, Behaviour, Medicine and its History, and Perform Health Clinic ,The Netherlands
Abstract
Current behavioural models describe interacting determinants of behaviour, yet rarely specify a functionally defined system that produces behaviour as its output. As a result, key phenomena such as effort, stress, persistence, and non-execution remain theoretically under-specified and are often attributed to individual deficits in motivation, self-regulation or capacity.
In this paper, behaviour is conceptualised as the output of a functional executive system: the behavioural organ. This organ is defined as a relational system consisting of the person, the environment, and designed behaviour (task). Its internal anatomy can be visualised by the behavioural triangle. Behaviour is continuously designed within this system and becomes observable only when executed outside it. Whether behaviour is executed effortlessly, with sustained effort, or not at all depends on the quality of relational fit within the system.
By explicitly distinguishing between designed and executed behaviour, and by conceptualising motivation and ability as emergent relational properties rather than individual determinants, this framework offers a novel ontological and functional–physiological account of behaviour. The behavioural organ provides a coherent foundation for understanding effort, stress, and behavioural breakdown as systemic signals rather than personal failures.
Introduction
Behavioural science has produced a wide range of models aimed at explaining why people behave as they do. Determinant-based frameworks such as the Theory of Planned Behaviour, the MOA model, the Triad model [1-2], and the COM-B model [3-4] have played a crucial role in structuring behavioural research, informing intervention design, and advancing prediction and categorisation. Their contribution to the field is substantial and undisputed.
Despite their usefulness, a fundamental question remains largely unanswered: how does behaviour actually come into existence as an executable output?
In most prevailing approaches, behaviour is conceptualised as the result of internal states – such as intentions, motivation, or capacity – moderated by contextual conditions. Behaviour itself is typically treated as a dependent variable: the observable endpoint of interacting determinants. As a consequence, experiential phenomena such as effortful behaviour, stress, persistence, and non-execution are commonly interpreted as failures of motivation, self-regulation, or individual ability.
Importantly, many contemporary behavioural models can be described as system-oriented in a descriptive sense. They acknowledge interaction between multiple determinants and recognise that behaviour does not arise from a single cause. However, they do not propose an ontological system that exists as a functional entity producing behaviour. Behaviour remains conceptualised as an outcome influenced by factors, rather than as the output of a system with an internal architecture, regulatory logic, and execution constraints.
This distinction is not merely semantic. Without an explicit behavioural production system, it becomes difficult – if not impossible – to explain why identical individuals may experience the same behaviour as effortless in one context and exhausting or unsustainable in another, even when motivation appears unchanged. Effort and stress are observed, measured, and intervened upon, but they are not structurally explained.
This paper proposes a different starting point. Behaviour is not approached as a choice, intention, or outcome, but as the output of a functional executive system: the behavioural organ. The term executive is used here to denote behavioural production and regulation at the system level, rather than executive cognitive functions located within the individual.
The behavioural organ framework conceptualises behaviour as something that is first designed within a relational system and only becomes observable when executed outside that system. Whether execution occurs effortlessly, with sustained effort, or not at all depends on the quality of relational fit within the system. In this view, motivation and ability are no longer treated as causal inputs preceding behaviour, but as emergent signals reflecting system coherence.
The present paper is intended as a conceptual and ontological contribution. It introduces the behavioural organ as a functionally specified system with a defined internal architecture and regulatory principles. Empirical operationalisation and validation are explicitly left to future work. The framework builds on a series of earlier conceptual papers that progressively formalised its relational architecture and execution logic.
The need for an ontological shift
The behavioural organ framework introduces an explicit ontological shift. Behaviour is not treated as a property of the person, nor as a direct response to environmental cues, but as the output of a relational system. This shift implies that behaviour must be analysed at the level of system architecture rather than individual determinants.
Within this framework, motivation and ability are no longer understood as causal inputs preceding behaviour, but as emergent properties of relational fit within the system. Effort and stress are not interpreted as failures of self-regulation, but as functional signals indicating misalignment between system components.
The term physiological is used here in a functional–regulatory sense. It refers to energetic cost, compensatory regulation, and system coherence, rather than to specific biological substrates or biomarkers.
To articulate this shift, behaviour is conceptualised through the lens of functional anatomy and physiology. Just as other distributed organ systems are defined by their function rather than by anatomical localisation, the behavioural organ is defined by its role in designing and regulating behaviour.
Intellectual and experiential origins of the model
The behavioural organ did not emerge as a purely theoretical construct. Its development reflects a sustained interaction between clinical practice, behavioural science, organisational contexts, and personal experience.
The relational foundation of the model was first articulated by Van de Graaf in 2025 in his paper entitled Reframing Human Behaviour Through the Behavioural Triangle [5]. Behaviour was conceptualised as emerging from interaction between Person, Task, and Organisation. That paper introduced the distinction between general (abstract) behaviour and visible (executed) behaviour, and emphasised relational quality – friction versus flow – as central to behavioural sustainability.
This framework was subsequently formalised at the level of system ontology in The behavioural organ: an introduction to the system that produces human behaviour [6]. There, the behavioural organ was defined as a distributed functional system spanning organism and world, and the distinction between designed behaviour and expressed behaviour was introduced alongside the energetic logic of fit and misfit.
The developmental trajectory of this thinking was described in The evolution of a behavioural model: how the triangle shaped my thinking [7], situating the model within a longer arc of medical, organisational, and behavioural practice.
Crucially, the present framework was further refined through ongoing dialogue and collaboration with Peter F. van de Graaf, health performance coach and co-author of this paper. These exchanges sharpened the focus on behavioural execution, effort, and sustainability across clinical, organisational, and everyday performance contexts, ultimately leading to the formulation of the behavioural organ as an explicit executive system of behaviour.
The internal architecture of the behavioural organ
The behavioural organ is conceptualised as a functional, non-anatomical organ composed of three elements arranged in a stable triangular architecture: the person, the environment, and designed behaviour (task). This internal architecture can be visualised as the behavioural triangle, which serves as a schematic representation of the anatomy of the behavioural organ (Figure 1).
The person contributes functional capacities and constraints, including skills, energy, needs, and life history. The environment provides structure, culture, norms, goals, and opportunities that shape behavioural demands. Designed behaviour represents the behavioural configuration that emerges from ongoing interaction between person and environment. Crucially, the task is not an externally imposed instruction but an implicit behavioural design reflecting what behaviour is expected and feasible within a given relational context.
Designed behaviour and executed behaviour
A central contribution of the behavioural organ framework is the explicit distinction between designed behaviour and executed behaviour. Designed behaviour refers to the behavioural configuration implicitly prepared within the behavioural organ as a result of person–environment interaction. Executed behaviour refers to the observable enactment of this design in the external world.
This distinction explains why individuals may experience strong intentions, commitment, or responsibility while simultaneously struggling to act – or do not act at all. Behavioural difficulty is not necessarily the result of insufficient motivation but may reflect a mismatch between system components that prevents designed behaviour from being executed without excessive effort.
Fit as the regulatory principle
Whether designed behaviour can be executed depends on the quality of relational fit within the behavioural organ. Fit refers to the alignment between the person and the task, the task and the environment, and the person and the environment. Fit is not an attribute of any single component but a relational property of the system as a whole.
Figure 2 illustrates behavioural execution as a function of relational fit. When fit is high, designed behaviour is executed as designed, effortlessly and sustainably. When fit is partial, behaviour can still be executed but requires sustained effort and increased energetic cost, often experienced as stress. When fit is insufficient, execution fails, resulting in avoidance, withdrawal, or behavioural breakdown.
Behavioural execution is therefore determined by systemic alignment rather than by individual motivation or ability alone.
Repositioning motivation and stress
Within the behavioural organ framework, motivation is not conceptualised as a driver of behaviour but as an emergent signal reflecting system coherence. Motivation tends to increase when relational fit improves and declines when misalignment persists. Similarly, stress is not interpreted as a personal weakness but as a physiological indicator of compensatory regulation under conditions of misfit.
This reframing resolves longstanding ambiguities in behavioural science regarding effortful behaviour, persistence, and apparent resistance to change. Behaviour that is difficult or unsustainable is no longer attributed to individual failure but understood as a predictable outcome of system dynamics.
Implications for behavioural science
By introducing the behavioural organ, this framework provides an explicit ontological foundation for behaviour. It offers a functional explanation for effort, stress, and non-execution and presents a relational alternative to individualised deficit models. Rather than replacing existing determinant frameworks, the behavioural organ complements them by supplying the architectural layer they lack.
Conclusion
This paper introduces the behavioural organ as a functional executive system that designs and regulates human behaviour. By distinguishing between designed and executed behaviour and by locating behavioural success or failure in relational fit rather than individual motivation, the framework offers a novel foundation for behavioural theory. The behavioural triangle makes the internal anatomy of this system explicit, while relational fit explains its functional physiology. Future work will focus on empirical operationalisation, longitudinal dynamics, and applications in health, work, and organisational contexts.
References
- Poiesz TBC. Gedragsmanagement. Waarom mensen zich (niet) gedragen. Wormer Inmerc BV 1999.
- Poiesz T. Redesigning psychology. In search of the DNA of behavior. Den Haag: Eleven International Publishing 2014.
- West R, Brown J. Theory of addiction, 2nd edition. UK: Wiley Blackwell 2013.
- Mitchie S, Atkins L, West R. The behaviour change wheel. A guide to designing interventions. Great Britain: Silverback Publishing 2014.
- Van de Graaf RC. Reframing human behaviour through the behavioural triangle: a relational systems model for understanding and change. J Health Behav Med Hist 2025-12.
- Van de Graaf RC. The behavioural organ: an introduction to the system that produces human behaviour. J Health Behav Med Hist 2025-24.
- Van de Graaf RC. The evolution of a behavioural model: how the triangle shaped my thinking. J Health Behav Med Hist 2025-1.