—A Conceptual Review in Ethology and Behavioural Science
Abstract
The concept of motivation is widely employed across ethology, behavioural science, psychology, and animal welfare research, yet it remains theoretically problematic and resistant to precise definition (Colgan, 1989; McFarland, 1989). Although often treated as a causal explanation of behaviour, motivation is better understood as an inferred construct that summarises the internal and external conditions under which goal-directed behaviour occurs (Dawkins, 1990). This review examines the historical development and theoretical uses of the term motivation within ethology and related disciplines, tracing its roots from instinct theory and drive-reduction models to contemporary regulatory and optimisation approaches. It argues that while motivation remains indispensable as a descriptive and heuristic concept, it cannot be exhaustively reduced to singular physiological or psychological mechanisms. A pluralistic and cautious approach is therefore warranted.
1. Introduction
Motivation is a term used so routinely that it is often assumed to be self-explanatory. In both scientific and everyday discourse, we speak as though its meaning were transparent and shared. Yet closer inspection reveals that motivation is conceptually ambiguous, theoretically overloaded, and frequently used as a placeholder for incomplete explanations (Colgan, 1989). The present review examines motivation not as a unitary mechanism, but as a functional and inferential construct employed to account for organised, goal-directed behaviour (McFarland, 1989).
For the purposes of this review, motivation is the functional organisation of behaviour arising from the interaction of an organism’s internal state, developmental history, and current environment such that behaviour is organised in ways that serve biologically and ecologically relevant functions.1 Rather than invoking subjective experience, conscious intention, or specific neural mechanisms, this definition identifies the explanatory domain within which the concept of motivation is employed (Tinbergen, 1963).
2. Early Models: Instinct and Drive
2.1 Instinct-Based Explanations
Early biological accounts of behaviour relied heavily on the concept of instinct. Influenced by evolutionary theory, behaviour was understood as the expression of inherited programmes shaped by natural selection (Darwin, 1859/2009). Survival and reproduction were treated as ultimate explanatory principles, with instinct serving as the proximate mediator (Lorenz, 1950).
Classical ethology formalised this approach. Ethologists defined instincts as species-typical, unlearned behaviour patterns elicited by specific stimuli (Lorenz, 1950; Tinbergen, 1951). Motivation, within this framework, was often conceptualised as the activation of innate releasing mechanisms or the accumulation of action-specific energy (Lorenz, 1981).
While heuristically useful, instinct-based explanations proved theoretically unstable. As Tinbergen (1963) noted, any unexplained behaviour could be accommodated by postulating a new instinct, rendering the concept effectively unfalsifiable.
2.2 Drive-Reduction and Homeostasis
To address these limitations, motivation was reconceptualised as internal drives. Drive-reduction theory proposed that organisms possess physiological needs—such as hunger or thirst—that generate states of arousal, motivating behaviour aimed at restoring homeostasis (see Colgan, 1989).
Early ethologists adopted modified versions of this framework, frequently employing hydraulic or energy-accumulation metaphors to describe motivational states (Lorenz, 1981). Although these models clarified certain behavioural regularities, they struggled to account for exploratory, play, and curiosity-driven behaviours that increase, rather than reduce, stimulation (McFarland, 1989).
3. Beyond Minimisation: Optimisation and Regulation
Subsequent theoretical developments rejected the assumption that organisms invariably seek to minimise stimulation. Instead, motivation came to be understood as the regulation of activity towards optimal levels of engagement with the environment (McFarland, 1989; Colgan, 1989). These models more readily accommodate behaviours such as exploration, novelty-seeking, and information gathering, which may themselves constitute functionally adaptive components of an organism’s extended phenotype (Dawkins, 1982).
Physiological regulation theories further emphasised the role of complex neural systems in coordinating motivational processes (Salamone & Correa, 2012; Salamone, 2024). However, even these accounts stop short of offering a complete explanation. Neural correlates of motivation describe how behaviour is regulated, not why particular goals are selected or prioritised (Dawkins, 1990).
4. Motivation, Learning, and Communication
Motivation is inseparable from learning processes.2 Reinforcement and punishment alter behaviour only insofar as the organism is motivated to engage with relevant stimuli (Breland & Breland, 1961; Catania, 1984). Apparent failures of conditioning often reflect motivational constraints rather than learning deficits, as demonstrated by instinctive drift (Breland & Breland, 1961) and by contemporary experimental work distinguishing learning capacity from motivational investment (Meagher et al., 2020).
Similarly, communication behaviours presuppose motivational states that render signalling functional in specific ecological and social contexts (Dawkins, 1990).
Strictly reflexive responses—such as simple Pavlovian reflexes—are sometimes cited as exceptions. Yet even here, contextual modulation and motivational gating suggest that motivation cannot be entirely excluded from explanatory accounts (Colgan, 1989).
5. Evolutionary and Sociobiological Perspectives
Sociobiology emerged as an attempt to ground motivation more firmly in evolutionary theory by integrating genetic, ecological, and behavioural data (Wilson, 1975). From this perspective, motivation reflects evolved behavioural tendencies shaped by selection pressures, rather than discrete internal drives.
While this approach clarified ultimate explanations, it did not eliminate conceptual ambiguity at the proximate level. Motivational terms often serve as shorthand for fitness-related behavioural patterns rather than as mechanistic explanations (Dawkins, 1982, 1990).
6. Motivation and Animal Welfare
In applied contexts, particularly animal welfare science, motivation is frequently invoked to justify claims about behavioural needs.3 Hughes and Duncan (1988) cautioned that the notion of ethological “need” must be used carefully, as motivational strength cannot be inferred directly from observed behaviour alone.
Within animal welfare science, motivation functions as both a descriptive and a normative concept, linking behavioural expression, welfare assessment, and ethical evaluation (Dawkins, 1990; Coria-Avila, 2022).
7. Conceptual Limits and Theoretical Caution
Despite more than a century of theoretical development, no single model of motivation has proven sufficient. Contemporary consensus recognises motivation as a necessary but incomplete explanatory construct, summarising behavioural regularities without fully specifying their causal architecture (Colgan, 1989; McFarland, 1989).
Accordingly, motivation should be treated neither as a literal internal entity nor as a purely linguistic convenience. Its value lies in its heuristic function—guiding inquiry while remaining open to revision (Tinbergen, 1963).
8. Conclusion
As an explanatory construct, motivation remains central to the study of behaviour precisely because it resists simple definition. Attempts to reduce it to instincts, drives, neural circuits, or genetic programmes have each illuminated certain aspects of behaviour while leaving others unexplained. A pluralistic and theoretically cautious approach—sensitive to both proximate and ultimate levels of analysis—remains the most defensible position at present. Rather than representing a single causal mechanism, motivation is best viewed as a conceptual framework that links physiological processes, behavioural organisation, and evolutionary function, thereby providing an indispensable explanatory framework within ethology and behavioural science.
Footnotes
- In this review, motivation is treated as an explanatory and heuristic construct rather than as a directly observable or unitary causal variable. References to motivational states are therefore not intended to imply the existence of a discrete internal entity, but to summarise the functional organisation of behaviour under particular internal and external conditions. This usage follows a long-standing ethological tradition and is consistent with multilevel analyses that distinguish proximate mechanisms from ultimate explanations (Tinbergen, 1963; Colgan, 1989; McFarland, 1989). ↩︎
- The present review does not treat motivation, drive, reinforcement, or learning as interchangeable explanatory terms. Motivation is used at a functional-descriptive level to characterise the conditions under which behaviour is organised and expressed, whereas reinforcement and punishment refer to empirically defined learning processes that modify behaviour contingent on its consequences. References to drives are retained only in their historical context. No claim is made that motivational constructs can be reduced to, or derived directly from, reinforcement histories or physiological variables alone (Breland & Breland, 1961; Catania, 1984; Colgan, 1989). ↩︎
- References to motivation in the context of animal welfare are not intended to imply that behavioural expression provides a direct or exhaustive measure of welfare or subjective experience. Motivational strength, preference, and welfare value are analytically distinct and may diverge under specific ecological, developmental, or experimental conditions. Motivational explanations are therefore used descriptively and comparatively, not as normative claims about welfare adequacy or ethical sufficiency (Hughes & Duncan, 1988; Dawkins, 1990; Coria-Avila, 2022). ↩︎
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Conflict of Interest Statement
The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.