Motivation

Abstract

Motivation is the set of processes that initiate, direct, and sustain goal-directed behavior. This article distinguishes the major kinds of motivation and the theories that explain them: the early drive and arousal accounts, on which behavior reduces need states and performance follows an inverted-U function of arousal; and the modern division between intrinsic motivation, doing something for its own satisfaction, and extrinsic motivation, doing it for a separable consequence. It develops self-determination theory, the dominant contemporary framework, and its finding that tangible rewards can undermine intrinsic interest. It reviews the achievement tradition — the need for achievement, expectancy-value theory, and goal setting — and the reward-learning neuroscience that separates wanting from liking. Three interactive demonstrations explore the arousal-performance curve, the overjustification effect, and the result that achievement motivation peaks at intermediate difficulty.

Keywords: motivation, intrinsic motivation, extrinsic motivation, self-determination theory, drive

Motivation is the answer to why an organism does what it does. Where perception and memory describe what a person knows, motivation describes what a person is moved to do about it: which of many possible actions is selected, how much effort is invested, and how long the effort is maintained in the face of difficulty or distraction. Psychologists conventionally decompose motivation into three components — the activation of behavior, its direction toward some goals rather than others, and its intensity and persistence over time (Ryan & Deci, 2000). A complete account of any behavior therefore needs a motivational story alongside its cognitive one: knowing how to solve a problem does not explain why a person attempts it, abandons it, or returns to it a week later.

The construct has always sat at the intersection of biology and cognition. The earliest scientific treatments, rooted in the physiology of need, cast motivation as the reduction of internal tension: a hungry animal acts to restore an equilibrium disturbed by deprivation. Later accounts added the pull of anticipated outcomes — incentives and goals that draw behavior forward rather than pushing it from behind — and, later still, the recognition that much human striving is not in the service of any deficit at all but of interest, curiosity, growth, and the exercise of competence (White, 1959; Ryan & Deci, 2020). The modern field spans this whole range, from the homeostatic drives shared with other animals to the distinctively human motivation to pursue self-chosen, meaningful ends.

The National Library of Medicine files motivation in its Medical Subject Headings under behavior and behavior mechanisms, defining it as “those factors which cause an organism to behave or act in either a goal-seeking or satisfying manner” — a deliberately broad definition that spans the deprivation states, drives, incentives, and goals surveyed below.

Types of Motivation

The Medical Subject Headings place motivation beneath behavior and behavior mechanisms and enumerate a set of narrower descriptors indexed under it (Table 1). These are the categories the National Library of Medicine uses to file the biomedical literature, and they mix several levels of analysis — deprivation states, dispositional drives, and cognitive constructs such as goals and intention — because MeSH is an indexing classification built for retrieval, not a theory of the mind. The subtypes are not mutually exclusive: a single act of striving can be described at once as an intention, in the service of a goal, expressing a need for achievement or power. Only two of these subtypes are themselves developed as articles on this site — intention and sense of agency — and only those are linked; the rest are listed as MeSH files them.

A more theoretically useful cut across these categories is the one psychology itself draws. Drive, food deprivation, and water deprivation belong to the homeostatic tradition, in which motivation restores a physiological set-point. Exploratory behavior, intention, sense of agency, and psychological aspirations belong to the modern study of self-initiated, cognitively represented striving. Achievement, goals, and power name the content of human motives — what people strive for. The sections that follow organize the field along this second, explanatory axis rather than the indexing one.

Drive, Arousal, and the Inverted U

The first scientific theories of motivation were theories of drive. On Clark Hull’s influential formulation, deprivation of a biological necessity — food, water, warmth — produces an aversive internal state of arousal, a drive, and behavior that reduces the drive is reinforced. Motivation, on this view, is a push from behind: the organism acts to discharge tension and return to homeostatic equilibrium. Drive theory elegantly explained deprivation-based behavior and dominated mid-century learning theory, and it survives in the MeSH subtypes of drive, food deprivation, and water deprivation.

But arousal and performance are not simply monotonically related. Yerkes and Dodson, in a 1908 study of discrimination learning in mice, found that increasing motivational arousal improved performance only up to a point, beyond which further arousal impaired it — an inverted-U function — and, crucially, that the optimal level of arousal was lower for more difficult discriminations (Yerkes & Dodson, 1908). The Yerkes-Dodson law (Figure 1) is why a moderate level of pressure sharpens performance on a routine task while the same pressure degrades performance on a hard one: complex tasks are optimized at lower arousal. The first demonstration lets the reader move arousal and task difficulty and watch the performance curve and its shifting optimum.

Drive theory could not, however, explain behavior that increases rather than reduces tension: animals and people explore, play, and seek novelty and challenge even when no deficit is present. Robert White marshaled this evidence into the concept of effectance or competence motivation — an intrinsic propensity to interact effectively with the environment for its own sake, not in the service of any drive (White, 1959). Abraham Maslow’s humanistic hierarchy of needs made a related move, ordering motives from physiological and safety needs at the base through belonging and esteem to self-actualization at the apex, and arguing that the higher, growth-oriented needs come into play once the lower deficiency needs are met (Maslow, 1943). Both accounts pointed beyond deprivation toward the motivation to grow, explore, and exercise one’s capacities — the territory the intrinsic-motivation tradition would later claim.

Intrinsic and Extrinsic Motivation

The organizing distinction in contemporary motivation science is between intrinsic and extrinsic motivation (Ryan & Deci, 2000). A person is intrinsically motivated when the activity is its own reward — the interest, enjoyment, and satisfaction inherent in doing it. A person is extrinsically motivated when the activity is a means to a separable end — a grade, a payment, a deadline, the avoidance of punishment. The two are not simply more and less of one quantity; they are qualitatively different, with different antecedents and different consequences for persistence, creativity, and well-being.

The finding that first made the distinction consequential was counterintuitive. Deci had participants work on an interesting puzzle and found that paying them for solving it reduced their subsequent free-choice engagement with it relative to unpaid participants: the extrinsic reward had undermined the intrinsic motivation (Deci, 1971). This overjustification effect — that a tangible, expected reward for an already-interesting activity can crowd out the original interest — was initially controversial, but a comprehensive meta-analysis of 128 experiments confirmed it: tangible rewards, especially when expected and contingent on task engagement, significantly diminish intrinsic motivation, while verbal praise tends to enhance it (Deci et al., 1999). The second demonstration lets the reader impose and remove an extrinsic reward and watch intrinsic engagement respond.

The theory that grew from this work is self-determination theory (SDT), developed by Deci and Ryan into the field’s dominant framework (Ryan & Deci, 2000). SDT holds that intrinsic motivation flourishes when three basic psychological needs are satisfied — autonomy (experiencing behavior as self-endorsed), competence (feeling effective), and relatedness (feeling connected to others) — and withers when they are thwarted (Vansteenkiste et al., 2020). Extrinsic rewards undermine intrinsic motivation precisely when they are experienced as controlling, shifting the perceived locus of causality from inside to outside the person. SDT also refines the extrinsic category into a continuum of autonomy: from amotivation (a complete absence of intention to act, arising when a person sees no value or no efficacy in an activity), through external regulation (acting purely for reward or to avoid punishment) and introjected regulation (acting to avoid guilt or bolster the ego), to identified and integrated regulation, in which the person has internalized the value of the activity so fully that the motivation, though still instrumental, is autonomous. A large meta-analysis supports treating these regulations as an ordered continuum from controlled to autonomous (Howard et al., 2017). The practical upshot — that autonomy-supportive contexts sustain motivation better than controlling ones — has reshaped education, work, and health care (Ryan & Deci, 2020).

Achievement, Goals, and Expectancy-Value

A parallel tradition asks not whether motivation is intrinsic or extrinsic but what people strive for and how strongly. David McClelland identified a small set of learned social motives — the needs for achievement, affiliation, and power — that vary across individuals and predict distinctive patterns of behavior, from entrepreneurial risk-taking to leadership (McClelland, 1985). John Atkinson formalized the achievement motive into a mathematical model: the tendency to approach a task is the product of the strength of the achievement motive, the subjective probability of success, and the incentive value of success — where incentive value rises as probability falls, so that success at an easy task is worth little and success at a near-impossible one is worth much but improbable (Atkinson, 1957). The model predicts that achievement-motivated people prefer tasks of intermediate difficulty, where the product is maximized — the result the third demonstration and the worked example develop.

Modern achievement theory descends from Atkinson through expectancy-value theory, developed by Jacquelynne Eccles and Allan Wigfield: the effort a person will invest in an achievement task is a joint function of their expectancy of success and the subjective value they place on it, where value decomposes into interest, usefulness, importance to identity, and cost (Eccles & Wigfield, 2002). The framework has since been recast as situated expectancy-value theory, emphasizing that expectancies and values are constructed in a specific social and cultural moment rather than being stable traits (Eccles & Wigfield, 2020). Two further ideas complete the picture. Albert Bandura’s self-efficacy — a person’s belief in their capacity to execute the actions a situation requires — supplies the expectancy term with a mechanism and predicts effort and persistence across domains (Bandura, 1977). Carol Dweck showed that whether people construe ability as fixed or as malleable shapes their achievement goals and their response to failure: a growth mindset fosters mastery-oriented persistence, while a fixed view fosters helpless withdrawal after setbacks (Dweck, 1986). Edwin Locke and Gary Latham’s goal-setting theory turns the same variables into a prescription: specific, difficult goals produce higher performance than vague or easy ones, provided the person is committed to them and has the ability and feedback to pursue them (Locke & Latham, 2002).

The Neuroscience of Motivation

Motivation has a well-mapped neural substrate centered on the midbrain dopamine system and its targets in the striatum and prefrontal cortex. A key conceptual advance was the dissociation of wanting from liking: Berridge and Robinson showed that dopamine mediates the incentive salience — the “wanting” — that makes a reward-associated cue attractive and pursued, which is neurally and psychologically distinct from the hedonic “liking” of the reward when obtained (Berridge & Robinson, 2016). The distinction explains why an addict can crave a drug intensely while deriving little pleasure from it, and why motivation to pursue a goal can outlast the enjoyment of attaining it. It maps loosely onto the psychological separation of anticipatory, approach-driving motivation from consummatory satisfaction.

This neuroscience is increasingly integrated with the intrinsic-motivation tradition. Di Domenico and Ryan reviewed evidence that intrinsically motivated behavior engages the same striatal reward circuitry as externally rewarded behavior, and that autonomy-supportive conditions are associated with distinctive patterns of neural activity — grounding SDT’s psychological constructs in reward neuroscience (Di Domenico & Ryan, 2017). Kou Murayama has pushed this integration furthest with a reward-learning framework that treats curiosity, interest, and the intrinsic-extrinsic distinction not as separate categories but as emerging from a common reward-learning system in which knowledge acquisition is itself rewarding (Murayama, 2022). On this view the old dichotomy between intrinsic and extrinsic reward dissolves into a single computational account of how the brain assigns value to states and actions — a direction that promises to reconnect the cognitive and biological halves of the field.

Worked Example

Atkinson’s model of achievement motivation is worth computing by hand because it yields a sharp, testable prediction. The tendency to approach an achievement task, T, is the product of three quantities: the strength of the person’s achievement motive, M; the subjective probability of success, P; and the incentive value of success, I. Atkinson’s key assumption is that incentive value is inversely related to probability — succeeding at something easy feels like little, succeeding at something hard feels like much — so that I = 1 − P. The model is therefore:

T = M × P × (1 − P)

Take a person with an achievement-motive strength of M = 2, and compare three tasks: an easy one (P = 0.9), a moderate one (P = 0.5), and a hard one (P = 0.1). The easy task gives T = 2 × 0.9 × 0.1 = 0.18. The hard task gives T = 2 × 0.1 × 0.9 = 0.18 — identical, because probability and incentive trade off symmetrically. The moderate task gives T = 2 × 0.5 × 0.5 = 0.50, the largest of the three. Because the product P(1 − P) is maximized at P = 0.5, an achievement-motivated person is predicted to be most strongly drawn to tasks of intermediate difficulty — hard enough to be worth doing, easy enough to be attainable. Doubling the motive to M = 4 doubles every tendency (the moderate task rises to 1.00) but leaves the peak at P = 0.5 unchanged: motive strength scales the pull without moving where it is strongest. This preference for moderate challenge is one of the most reliably observed signatures of achievement motivation, and it is what the third demonstration traces as the probability of success is varied.

Discussion

The history of motivation research is a movement outward from the body. The drive theories took the deprived, tension-reducing organism as the model of all motivation and struggled to accommodate curiosity, play, and the pursuit of difficulty for its own sake. The competence and humanistic accounts, and then self-determination theory, inverted the emphasis, treating the exploring, growth-seeking organism as the norm and asking what social conditions sustain or undermine its native tendency to act (White, 1959; Ryan & Deci, 2020). The achievement tradition, meanwhile, held the middle ground, formalizing how the value and attainability of specific outcomes combine to produce striving (Atkinson, 1957; Eccles & Wigfield, 2002). These are not competing theories of a single phenomenon so much as accounts of different regions of a large space — from homeostatic drive to self-actualization — that the single English word motivation happens to cover.

What unifies the modern field is a shift from asking how much motivation a person has to asking what kind. The overjustification effect made the point vivid: adding reward can increase measured effort in the short run while corroding the autonomous motivation that sustains it, so that more extrinsic motivation can mean less of the intrinsic kind (Deci et al., 1999). This qualitative view — that autonomous and controlled motivation differ in their downstream effects on persistence, creativity, and well-being — is the field’s most consequential practical legacy, and it is where its applied and theoretical branches meet.

Current Directions

The most active current effort is to reunify motivation science around a computational, reward-learning account. Rather than cataloguing intrinsic and extrinsic motivation, curiosity, and interest as separate constructs, Murayama’s reward-learning framework derives them from a common mechanism in which acquiring information is itself intrinsically rewarding, subject to the same value-learning computations as any other reward (Murayama, 2022). This connects the psychology of motivation to the reinforcement-learning models that dominate the neuroscience of reward and to the wanting-liking dissociation (Berridge & Robinson, 2016), and it offers a principled way to ask when a reward will enhance and when it will undermine engagement.

A second direction is the situating of motivation in its social and cultural context. Situated expectancy-value theory reframes expectancies and values as constructed in the moment, shaped by identity, stereotype, and immediate social ecology rather than as stable individual traits (Eccles & Wigfield, 2020), and self-determination research has increasingly examined how cultures and institutions support or thwart the basic needs across very different settings (Vansteenkiste et al., 2020). The two directions are complementary: one seeks the general computation beneath all motivation, the other the specific conditions that determine which motivation a given person, in a given place, actually has.

Common Misconceptions

Rewarding people always increases their motivation.

For an activity a person already finds interesting, a tangible expected reward can undermine intrinsic motivation — the overjustification effect — a result confirmed across 128 experiments; verbal praise, by contrast, tends to help (Deci, 1971; Deci et al., 1999).

More arousal or pressure always improves performance.

Performance follows an inverted-U function of arousal, and the optimum is lower for harder tasks, so the pressure that sharpens an easy task can wreck a difficult one (Yerkes & Dodson, 1908).

Highly motivated people take on the hardest possible challenges.

Achievement-motivated people prefer tasks of intermediate difficulty, where the product of the probability and incentive value of success is greatest, not the hardest tasks available (Atkinson, 1957).

Glossary

Achievement motivation.

The disposition to strive for success against a standard of excellence, associated with a preference for tasks of intermediate difficulty.

Amotivation.

The state of lacking any intention to act, at the controlled end of the self-determination continuum, arising when a person sees no value or no efficacy in an activity.

Autonomy.

In self-determination theory, the basic need to experience one’s behavior as self-endorsed and volitional rather than controlled from outside.

Competence.

The basic need to feel effective in one’s interactions with the environment; White’s effectance motivation is its historical antecedent.

Drive.

An aversive internal state of arousal produced by a biological need, which impels the organism to act so as to reduce it.

Expectancy-value theory.

The account on which achievement effort is the joint product of the expectancy of success and the subjective value of the outcome, later recast in situated form.

Extrinsic motivation.

Motivation to perform an activity as a means to a separable consequence, such as a reward, grade, or the avoidance of punishment.

Goal-setting theory.

Locke and Latham’s account on which specific, difficult goals raise performance relative to vague or easy ones, given commitment, ability, and feedback.

Hierarchy of needs.

Maslow’s ordering of human motives from physiological and safety needs through belonging and esteem to self-actualization, with higher needs engaged once lower ones are met.

Incentive.

The anticipated value of an outcome that pulls behavior toward it; in Atkinson’s model, inversely related to the probability of success.

Intrinsic motivation.

Motivation to perform an activity for the inherent interest and satisfaction it provides, rather than for any separable consequence.

Motivation.

The set of processes that activate behavior, direct it toward some goals rather than others, and govern its intensity and persistence.

Need for achievement.

One of McClelland’s learned social motives, the recurrent concern with meeting a standard of excellence; abbreviated nAch.

Overjustification effect.

The reduction of intrinsic motivation for an already-interesting activity that follows the introduction of a tangible, expected extrinsic reward.

Self-determination theory.

Deci and Ryan’s framework holding that autonomous motivation and well-being depend on satisfying the basic needs for autonomy, competence, and relatedness.

Self-efficacy.

Bandura’s construct: a person’s belief in their capacity to carry out the actions needed to attain a goal, which predicts effort and persistence.

Yerkes-Dodson law.

The principle that performance is an inverted-U function of arousal, with the optimal level of arousal lower for more difficult tasks.

Key Researchers

Edward L. Deci (1942-2026). Late professor of psychology at the University of Rochester; with Richard Ryan he founded self-determination theory and demonstrated that extrinsic rewards can undermine intrinsic motivation. ORCID - Wikipedia - Wikidata - Google Scholar

Carol S. Dweck (b. 1946). Professor of psychology at Stanford University; her work on fixed and growth mindsets showed how implicit theories of ability shape achievement motivation and the response to failure. ORCID - Wikipedia - Wikidata - Google Scholar

Jacquelynne S. Eccles (b. 1944). Professor at the University of California, Irvine; developed the expectancy-value theory of achievement motivation and its later situated form. ORCID - Wikipedia - Wikidata - Google Scholar

Edwin A. Locke (b. 1938). Emeritus professor at the University of Maryland; with Gary Latham he built goal-setting theory, showing that specific, difficult goals raise task performance. Wikipedia - Wikidata

Abraham Maslow (1908-1970). Late professor of psychology at Brandeis University; a founder of humanistic psychology who proposed the hierarchy of needs in his 1943 paper on human motivation. Wikipedia - Wikidata

David C. McClelland (1917-1998). Late professor of psychology at Harvard and Boston Universities; identified the learned needs for achievement, affiliation, and power and the acquired-needs theory of motivation. Wikipedia

Kou Murayama (contemporary). Professor at the University of Tuebingen’s Hector Research Institute; developed a reward-learning framework integrating curiosity, interest, and intrinsic and extrinsic reward. ORCID - Google Scholar - Faculty Page

Richard M. Ryan (contemporary). Professor at the Australian Catholic University and emeritus at the University of Rochester; co-founder with Edward Deci of self-determination theory and basic psychological needs theory. ORCID - Wikipedia - Wikidata

Allan Wigfield (contemporary). Emeritus professor at the University of Maryland; co-developer with Jacquelynne Eccles of the expectancy-value theory of achievement motivation. ORCID - Google Scholar - Faculty Page

Frequently Asked Questions

What is motivation in psychology?
Motivation is the set of processes that initiate, direct, and sustain behavior — what activates action, steers it toward some goals rather than others, and determines how much effort is invested and for how long. It spans biological drives and distinctively human striving (Ryan & Deci, 2000).

What is the difference between intrinsic and extrinsic motivation?
Intrinsic motivation is doing an activity for the inherent interest and satisfaction it provides; extrinsic motivation is doing it for a separable consequence such as a reward, grade, or the avoidance of punishment. The two differ in their effects on persistence, creativity, and well-being (Ryan & Deci, 2000).

Can rewards reduce motivation?
Yes. For an activity a person already finds interesting, a tangible, expected reward can undermine intrinsic motivation — the overjustification effect — a result confirmed by a meta-analysis of 128 experiments. Verbal praise, by contrast, tends to enhance intrinsic motivation (Deci et al., 1999).

What is self-determination theory?
Self-determination theory, developed by Deci and Ryan, holds that autonomous motivation and psychological well-being depend on satisfying three basic needs — autonomy, competence, and relatedness — and that controlling conditions that thwart these needs undermine motivation (Ryan & Deci, 2000; Vansteenkiste et al., 2020).

What is the Yerkes-Dodson law?
The Yerkes-Dodson law states that performance improves with arousal up to an optimum and declines beyond it, forming an inverted U, and that the optimal level of arousal is lower for more difficult or complex tasks (Yerkes & Dodson, 1908).

Why do achievement-motivated people prefer moderately hard tasks?
Atkinson’s model makes the tendency to approach a task the product of the probability of success and its incentive value, which trade off inversely. The product is largest at intermediate difficulty, so achievement-motivated people are drawn to tasks that are challenging but attainable (Atkinson, 1957).

What is expectancy-value theory?
Expectancy-value theory holds that the effort a person invests in an achievement task is the joint product of their expectancy of success and the subjective value they place on the outcome, where value includes interest, usefulness, importance, and cost (Eccles & Wigfield, 2002).

How does the brain generate motivation?
Motivation depends largely on the midbrain dopamine system, which mediates the “wanting” or incentive salience that drives pursuit of a reward — distinct from the “liking” of the reward itself. Recent work treats curiosity and intrinsic motivation as products of the same reward-learning system (Berridge & Robinson, 2016; Murayama, 2022).

References