AP Syllabus focus:
‘Infants are born with reflexes such as the rooting reflex, which indicate typical physical development and support early survival.’
Infant reflexes are automatic behaviors present at birth that help newborns eat, avoid danger, and interact with caregivers. In AP Psychology, they also function as early indicators of typical nervous system development.
What infant reflexes are and why they matter
Newborns arrive with a set of built-in responses often called primitive reflexes. These reflexes are especially important because infants initially have limited voluntary control and depend on quick, automatic actions for survival.
Reflex: an involuntary, automatic response to a specific stimulus, produced by neural circuits that require little to no conscious control.
Two major AP Psychology uses of infant reflexes:
Survival functions: feeding and basic protection.
Developmental screening: presence, strength, symmetry, and timing help indicate typical physical development (especially healthy neurological functioning).
Reflexes that support feeding and early survival
This figure shows four common newborn reflexes: the Moro (startle) reflex, palmar grasp reflex, rooting reflex, and the tonic neck (“fencing”) reflex. Seeing the distinct body postures side-by-side makes it easier to connect each reflex to its trigger (e.g., sudden support change vs. cheek stimulation) and its developmental meaning as an early, automatic nervous-system response. Source
Rooting reflex (finding food)
Rooting reflex: when the infant’s cheek is stroked, the baby turns toward the touch and opens the mouth.
Survival value: helps a newborn locate the nipple or bottle to begin feeding.
Caregiver bond: encourages close contact during feeding, increasing warmth, protection, and regular nourishment.
Sucking reflex (getting nutrition)
When something touches the roof of the mouth, infants automatically suck.
Survival value: enables efficient feeding before an infant can intentionally coordinate complex mouth movements.
Often works together with rooting, forming a coordinated “find-and-feed” sequence.
Reflexes that support protection and caregiver contact
Moro (startle) reflex (responding to sudden change)
This clinical illustration depicts the Moro (startle) reflex sequence, emphasizing the characteristic abduction/extension phase followed by adduction/flexion. It reinforces how the reflex is elicited by sudden changes (e.g., loss of support) and why clinicians attend to the strength and symmetry of the response when screening early neurological function. Source
A sudden loss of support or loud noise can trigger a startle: arms extend outward and then pull inward.
Possible survival value: may promote clinging or signal distress, increasing the chance a caregiver responds quickly.
Developmental indicator: a strong, symmetric response is typically expected early in life; marked asymmetry can be a red flag for injury or neurological issues.
Palmar grasp reflex (holding on)
Touching the infant’s palm leads to an automatic grip.
Survival value: supports close contact with a caregiver (important for warmth and safety).
Foundation for later action: early grasping is not the same as voluntary holding, but it reflects developing motor pathways.
Reflexes that indicate typical neurological development
In AP Psychology, reflexes are important not because students must memorise every clinical detail, but because they illustrate how early behavior reflects the developing nervous system.
Babinski reflex (foot response)
Stroking the sole of the foot produces a characteristic toe response in infants.
Developmental indicator: expected in infancy due to immature neural control; changes as the brain and spinal pathways mature.
Stepping reflex (early walking-like movements)
When held upright with feet touching a surface, some infants make stepping motions.
Developmental indicator: shows early motor patterning, even before true walking is possible.
Tonic neck (“fencing”) reflex (posture pattern)
Turning an infant’s head can produce an arm/leg posture pattern.
Developmental indicator: reflects early coordination patterns that usually fade as voluntary control strengthens.
Timing: presence, disappearance, and “red flags”
A key idea for this subsubtopic is that reflexes are most informative when you consider timing:
Many primitive reflexes are present at birth (or shortly after).
Many weaken and disappear as the cortex matures and voluntary motor control increases.
Some reflex responses change form rather than simply “vanish,” reflecting more advanced control.
Patterns that can suggest atypical development (general AP-level emphasis):
Absent reflexes when they are typically expected (may suggest neurological immaturity, injury, or sensory/motor impairment).
Asymmetrical reflexes (may suggest localized problems affecting muscles, nerves, or the brain).
Persistence well past the typical period (may suggest delays in neurological maturation or difficulties integrating automatic responses with voluntary control).
How reflexes connect to survival and typical development
Infant reflexes illustrate two core developmental points aligned to the syllabus statement:
Supporting early survival: reflexes like rooting and sucking directly aid feeding; protective/contact-related reflexes can increase caregiver proximity and responsiveness.
Indicating typical physical development: because reflexes rely on basic neural circuits, they provide a window into early central nervous system functioning before sophisticated voluntary behavior appears.
Clinicians and researchers use standardized observations of these reflexes (strength, consistency, and symmetry) as part of judging whether early physical development is proceeding in an expected way.
FAQ
Often, reflexes appear weaker or less coordinated in premature infants because the nervous system is less mature.
Clinicians typically interpret reflexes relative to gestational age rather than calendar age.
Reflexes are usually elicited with gentle touch, movement, or positional changes (e.g., stroking the cheek or sole).
Examiners look for consistency, symmetry, and how easily the response is triggered, while keeping the infant calm and supported.
Yes. Sedating medications, some pain relief drugs, or substance exposure can temporarily reduce alertness and weaken responses like sucking.
This may complicate early feeding and can make reflex-based assessment less clear in the first hours or days.
Some practitioners claim retained primitive reflexes relate to later issues (e.g., coordination or attention), but evidence is mixed.
Research quality varies, and many studies struggle to separate reflex retention from broader developmental differences.
Support is limited and depends on the programme and outcome measured.
Some small studies report motor improvements, but robust evidence (large, well-controlled trials) is not consistent; benefits may reflect general motor practice rather than specific “integration.”
Practice Questions
Explain what the rooting reflex is and give one reason it supports infant survival. (2 marks)
1 mark: Accurate description of rooting (turning head/opening mouth toward cheek stimulation).
1 mark: Survival link (helps locate nipple/bottle to feed; promotes successful feeding).
Describe how infant reflexes can be used to indicate typical physical development, using two named reflexes in your answer. (6 marks)
1 mark: States that reflexes are automatic, present in infancy, and reflect nervous system functioning/development.
1 mark: Explains that presence/strength/symmetry/timing can indicate typical vs atypical development.
2 marks: Names and accurately describes Reflex 1 (e.g., Moro, palmar grasp, sucking, Babinski, stepping).
2 marks: Names and accurately describes Reflex 2 and links each reflex to developmental indication (e.g., absence, asymmetry, or persistence suggesting possible neurological issue; typical presence suggesting typical development).
