AP Syllabus focus:
‘Many non-human animals are motivated by instincts, but humans do not appear to show instinctual behavior.’
Instinct theory explains some animal behavior as biologically prewired rather than learned. This page focuses on what “instincts” mean in modern psychology, how they guide animal actions, and why human behavior is rarely classified as instinctual.
Core idea: Instincts as innate motivation in animals
In instinct theory, certain behaviors are triggered reliably by specific cues and unfold in a stereotyped way, supporting survival and reproduction (e.g., feeding, mating, defense, migration).
Instinct: An innate (inborn), biologically based tendency to perform a behavior that is characteristic of a species and relatively resistant to learning or conscious control.
Instinct accounts are most persuasive when a behavior:
Appears in most members of a species (species-typical)
Emerges without training or observation
Is adaptive (increases survival/reproductive success)
Is fairly consistent across environments
Ethology and instinctive patterns
Much of the evidence for instincts comes from ethology, the study of animal behavior in natural settings. Ethologists documented predictable, inherited action sequences that can be released by simple stimuli.
Fixed action pattern (FAP): A biologically programmed sequence of behaviors that, once triggered, typically runs to completion in a similar way each time.
This diagram depicts the greylag goose’s egg-retrieval fixed action pattern: an egg-like object outside the nest releases a stereotyped rolling sequence that brings the object back to the nest. It also illustrates how an exaggerated, egg-like object can function as a supernormal stimulus, eliciting the same retrieval sequence even when the cue is not a natural egg. Source
A related idea is the sign stimulus (sometimes called a releaser): an external cue that activates an instinctive response. In classic demonstrations, animals may even respond more strongly to supernormal stimuli (exaggerated cues) than to natural ones, suggesting built-in “templates” for what to respond to.
Why call these behaviors “motivated”?
Instinctive behavior is often discussed as motivation because it:
Directs behavior toward goals (food, shelter, mates, offspring)
Is energised by internal states (e.g., hormonal changes) and timed to developmental windows or seasons
Occurs without deliberate planning or explicit reward learning
Instinct theory does not claim animals never learn; instead, it highlights that some key behaviors have strong innate constraints and predictable triggers.
Humans: why most behavior is not labelled instinctual
The syllabus emphasises that “humans do not appear to show instinctual behavior.” Psychologists are cautious about calling complex human actions instincts because:
Human behaviors are highly variable across cultures and situations
Cognition (planning, language, self-control) can override impulses
Social learning and norms strongly shape what people do and when they do it
The same outcome (e.g., aggression, caregiving) can arise from many different pathways, not a single fixed program
This does not mean biology is irrelevant. Humans show reflexes (simple, automatic responses) and may have genetic predispositions that make certain responses easier to acquire, but these typically lack the rigid, species-uniform, cue-bound structure seen in many animal FAPs.
Reflex: A simple, automatic response to a specific stimulus that involves minimal processing (often mediated by the spinal cord or brainstem), rather than a complex, species-typical action sequence.
This reflex-arc diagram shows how sensory (afferent) input travels to the spinal cord and is rapidly converted into a motor (efferent) output to an effector. The layout emphasizes why reflexes are fast and relatively automatic compared with fixed action patterns, which are longer, species-typical behavioral sequences. Source
What to be able to do on AP Psychology
Distinguish instincts/FAPs (innate, species-typical, triggered, stereotyped) from reflexes (simple stimulus–response) and from flexible, learned human behaviors.
Explain why instinct theory fits many non-human animal behaviors well, but is limited for explaining most human actions due to flexibility, culture, and cognition.
Use correct vocabulary: instinct, FAP, sign stimulus, supernormal stimulus, ethology, reflex.
FAQ
They use methods such as cross-fostering, rearing without models, and comparing populations across environments.
Strong evidence includes early emergence, minimal practice needed, and high similarity across individuals despite different experiences.
Yes. Hormones often modulate timing and intensity rather than create the behavioural pattern itself.
For example, hormonal shifts can increase responsiveness to particular sign stimuli during mating or parenting periods.
A supernormal stimulus is an exaggerated version of a natural cue that elicits a stronger instinctive response.
It matters because it shows how some behaviours rely on built-in trigger features rather than detailed reasoning or learning.
Typically no, because reflexes are simpler and more localised stimulus–response patterns.
Instincts (in the ethological sense) are more complex, species-typical sequences guided by sign stimuli and often involving multiple coordinated actions.
In AP terms, it’s safer to say most human behaviours are not instinctual in the strict ethological sense.
Humans may have biological predispositions and automatic tendencies, but these are usually shaped heavily by learning, culture, and conscious control.
Practice Questions
Define a fixed action pattern and state how it is typically triggered. (2 marks)
1 mark: Accurate definition of FAP as an innate, stereotyped sequence that tends to run to completion.
1 mark: States it is triggered by a specific cue/sign stimulus (releaser).
Explain why instinct theory is more useful for describing many non-human animal behaviours than for explaining most human behaviours. Refer to at least two features of instinctive behaviour. (6 marks)
Up to 2 marks: Identifies features of instinctive behaviour (e.g., innate, species-typical, cue-triggered, stereotyped, runs to completion).
Up to 2 marks: Applies these features to non-human animals (e.g., reliable patterns with sign stimuli; adaptive functions).
Up to 2 marks: Explains limits for humans (e.g., cultural variation, cognitive control, learning and flexibility; complex behaviours not fixed sequences).
