Biological approaches, Section 2 (Combined)

Biological approach (definition)

All thoughts, feelings and behaviours have a physiological/biological cause; study brain, nervous system, endocrine system, neurochemistry and genes, and consider evolutionary significance of behaviour.

Key assumption: determinism

Behaviour is determined by biological factors such as genes, hormones and brain structure (limited free will).

Key assumption: reductionism

Explains complex behaviour by reducing it to simpler biological processes (e.g., neurotransmitters, hormones).

Key assumption: nature over nurture

Emphasises genetic and physiological influences while acknowledging environmental effects.

Cambridge assumption 1

Behaviour, cognitions and emotions can be explained by brain function and effects of hormones, genetics and evolution.

Cambridge assumption 2

Similarities and differences between people can be understood in terms of biological factors and their interaction with other factors.

Core area: genetics

How genes influence behaviour; includes heritability, gene–environment interactions and behavioural genetics.

Core area: neurochemistry

Roles of neurotransmitters and hormones in behaviour; includes psychopharmacology.

Core area: brain

How brain structures and neural networks relate to behaviour.

Core area: physiology

How bodily systems (nervous, endocrine) influence behaviour.

Core area: evolution

How natural selection shapes adaptive behaviours that aid survival and reproduction.

Main research methods

Lab experiments, case studies, correlational studies, brain imaging (fMRI, PET, EEG, CT/CAT).

Strength: scientific basis

Uses empirical, measurable methods (e.g., imaging, experiments) which increase reliability and credibility.

Strength: practical applications

Led to effective treatments (e.g., antidepressants, antipsychotics) and biofeedback for stress management.

Strength: nature–nurture contribution

Clarifies genetic/physiological influences while allowing for interactions with environment.

Contribution: gender development

Shows influence of hormones and genes on gender identity and development.

Contribution: abnormality

Links between biological factors (e.g., serotonin in eating disorders) and psychopathology.

Contribution: stress

Explains stress responses via sympathetic nervous system and endocrine interactions.

Limitation: reductionism

Oversimplifies behaviour; may neglect social and cognitive factors.

Limitation: determinism

Downplays free will; may ignore environmental shaping and learning.

Limitation: ignores subjective experience

Focus on objective data may overlook consciousness and lived experience.

Limitation: limited explanatory power

Struggles to fully explain complex behaviours (e.g., creativity, altruism).

Limitation: animal–human generalisation

Findings from animals may not translate directly to humans.

Alternative names for field

Biopsychology, psychobiology, behavioural neuroscience.

Brain–behaviour relationship

Complex and bidirectional: brain influences behaviour; behaviour reshapes brain (neuroplasticity).

Localisation of function (definition)

Specific brain areas correspond to specific functions (e.g., motor cortex → movement, auditory cortex → hearing).

Split

brain research (idea)

Nervous system: CNS

Central nervous system = brain and spinal cord.

Nervous system: PNS

Peripheral nervous system = somatic + autonomic systems (outside CNS).

Somatic nervous system

Controls voluntary skeletal muscle movements and transmits sensory information.

Autonomic nervous system

Controls involuntary functions (heart rate, digestion, breathing).

Autonomic: sympathetic

Prepares body for action (fight

Autonomic: parasympathetic

Restores balance (rest

Endocrine system (overview)

Network of glands producing hormones; interacts closely with nervous system; affects mood, metabolism, growth and stress.

Hormones vs neurotransmitters

Hormones: endocrine glands → bloodstream → distant targets, slower, longer

Cerebrum (definition)

Largest brain region including cerebral cortex and subcortical structures (e.g., hippocampus, basal ganglia); divided into two hemispheres and lobes.

Cerebral cortex (overview)

Wrinkled outer layer of cerebrum; grey matter; involved in higher

Cerebral cortex features

Thin layer with gyri (ridges) and sulci (furrows); organised into right and left hemispheres.

Lobes of the cortex

Frontal, parietal, temporal, occipital.

Frontal lobe functions

Decision

Parietal lobe functions

Integrates somatosensory info (touch, pressure, temperature), spatial mapping, attention; coordinates movement in response to environment.

Temporal lobe functions

Hearing, memory, emotion; language comprehension (left side), recognition of faces/objects (right side).

Occipital lobe functions

Processes visual info (colour, motion, orientation); supports object/face recognition and depth perception.

Limbic system (overview)

Emotion and memory network including hippocampus, amygdala, hypothalamus and cingulate gyrus.

Hippocampus (role)

Forms episodic memories and supports spatial memory; damage → severe memory impairment.

Amygdala (role)

Generates emotional responses (fear, anger, anxiety, happiness) and tags memories with emotion; damage → emotion recognition deficits, irritability.

Hypothalamus (role)

Homeostasis (hunger, thirst, temperature, heart rate, sexual behaviour); interface between nervous and endocrine systems; key in stress response.

Cingulate gyrus (role)

Regulates emotion, pain and autonomic motor functions; involved in fear prediction/avoidance; damage → inappropriate emotions, altered pain, learning issues.

Anterior cingulate cortex (ACC)

Autonomic regulation (heart rate, blood pressure) and cognition (reward anticipation, decision

Posterior cingulate cortex (PCC)

Activates during retrieval of autobiographical episodic memories; part of “limbic lobe.”

Neuroplasticity (definition)

Brain’s ability to change structure and function by forming/strengthening/removing neural connections.

Neuroplasticity across lifespan

High in childhood; reduces with age but remains: unused pathways pruned, used pathways strengthened; new pathways can form.

Functional recovery after trauma

Other areas may take over functions of damaged regions; enables recovery after stroke or injury.

Plasticity mechanism: dormant synapses

Previously inactive connections can be recruited when usual pathways are damaged (Wall, 1977).

Plasticity mechanism: axon sprouting

Intact neurons grow extra endings to reconnect with targets after axonal damage.

Neurotransmitters (definition)

Chemical messengers released at synapses to transmit signals between neurons; essential for mood, sleep, appetite, cognition.

Neurotransmitters: action speed

Act locally and very fast across the synaptic cleft; bind to receptors causing postsynaptic effects.

Dopamine (summary)

Reward/motivation, movement, attention; imbalance linked to Parkinson’s disease and schizophrenia.

Serotonin (summary)

Mood, appetite, sleep, pain perception; low levels linked to depression.

Norepinephrine (summary)

Alertness, attention, fight

Acetylcholine (summary)

Memory, learning and muscle contraction.

GABA (summary)

Primary inhibitory transmitter; calms brain activity; low levels linked to anxiety.

Glutamate (summary)

Primary excitatory transmitter; learning and memory; excessive levels can be neurotoxic.

Case study: Phineas Gage (facts)

1848 rail worker; iron bar through skull; survived; major personality change; damage to prefrontal cortex affected moral decision

Gage—takeaway

Links frontal lobe/prefrontal cortex to personality, planning, social behaviour and emotion regulation.

Case study: Dina Sanichar (facts)

Feral child in India; minimal language; animal

Sanichar—takeaway

Highlights impact of early environment on socialisation and language; shows limits of biological maturation without human input.

Evolutionary psychology (definition)

Explains behaviour through evolved adaptations that increased survival/reproduction.

Natural selection (in behaviour)

Genetic variations that aid survival/reproduction are passed to offspring, shaping behavioural tendencies.

Behavioural genetics (methods)

Twin and family studies, adoption studies to estimate heritability and gene–environment interplay.

Heritability (definition)

Proportion of variation in a trait within a population attributable to genetic differences.

Gene–environment interaction

Genetic predispositions can be triggered, enhanced or suppressed by environmental factors.

Psychopharmacology (definition)

Study and use of drugs to treat mental disorders by modulating neurotransmitter systems.

Imaging: MRI/fMRI

Structural MRI for anatomy; fMRI for blood

Imaging: PET

Tracks metabolic activity using radiotracers to map functional processes.

Imaging: EEG

Measures electrical activity via scalp electrodes; good temporal resolution for brain rhythms/events.

Imaging: CT/CAT

CNS vs PNS (quick compare)

CNS = processing/integration; PNS = relay between CNS and body (voluntary and autonomic control).

ANS balance (exam tip)

Stress response = sympathetic dominance; recovery/relaxation = parasympathetic dominance.

Drug therapy—example effect

SSRIs increase synaptic serotonin to alleviate depressive symptoms.

Biofeedback—example effect

Gives physiological feedback (e.g., heart rate) to help patients learn stress reduction/control.

Subjective experience (limitation)

Objective measures can miss qualia (what it feels like) and meaning to the individual.

Ethics/limitations of case studies

Rich detail but low generalisability; brain damage cases have uncontrolled variables.

Dement & Kleitman (1957) — Aim

To test whether dreaming is primarily associated with REM sleep, whether reported dream length matches REM duration, and whether eye-movement patterns relate to dream content.

Dement & Kleitman — Method/Design

Laboratory experiment with repeated measures; physiological recordings using EEG/EOG; participants woken in REM or NREM sleep and asked to report dreams.

Dement & Kleitman — Sample

9 adults (7 male, 2 female), sleeping in a laboratory.

Dement & Kleitman — Procedure

Participants slept with electrodes attached to eyes and scalp. When EEG showed REM or NREM, they were woken by a bell and asked if they were dreaming, how long it felt, and to describe dream content.

Dement & Kleitman — Findings

Dream recall was much more likely after REM than NREM; estimates of dream length matched REM duration; eye-movement directions often matched dream scenes (e.g., side-to-side = watching people throw tomatoes).

Dement & Kleitman — Conclusion

REM sleep is strongly linked to dreaming; REM duration reflects dream length; eye movements reflect dream imagery.

Dement & Kleitman — GRAVE

• Generalisability: small, mostly male sample, low representativeness.

• Reliability: strong, standardised EEG procedures, replicable.

• Application: informs sleep research and diagnosis of sleep disorders.

• Validity: high internal (objective EEG) but low ecological (sleeping in lab with electrodes).

• Ethics: minimal harm, but sleep disruption may have caused fatigue.

Dement & Kleitman — Debates

Nature (biological sleep stages cause dreams), reductionist (focuses on physiology only), deterministic (brain state determines dreams).

Hassett et al. (2008) — Aim

To test whether sex differences in toy preferences are biologically influenced by studying rhesus monkeys raised without human cultural gender norms.

Hassett et al. — Method/Design

Field experiment with controlled observation; independent-measures design; male vs female monkeys observed with toy sets.

Hassett et al. — Sample

34 rhesus monkeys (23 female, 11 male) from a larger group, observed in social groups.

Hassett et al. — Procedure

Monkeys given access to “masculine” wheeled toys, “feminine” plush toys, and neutral toys. Time spent interacting with each toy recorded; toy placements counterbalanced.

Hassett et al. — Findings

Male monkeys preferred wheeled toys; females interacted with both types but showed relatively more interest in plush toys. Some female preferences varied with social rank.

Hassett et al. — Conclusion

Sex-typed toy preferences are partly biological and not entirely due to human socialisation.

Hassett et al. — GRAVE

• Generalisability: caution when applying from monkeys to humans, but evolutionary parallels exist.

• Reliability: strong, with standardised coding and counterbalancing.

• Application: informs debates on gender development and biological influences.

• Validity: good internal (controls in place) but lower ecological (monkeys playing with human toys).

• Ethics: adhered to animal welfare standards, enrichment-type stimuli provided.

Hassett et al. — Debates

Supports nature/evolutionary basis of gender differences; reductionist (focuses on biology, ignores culture); deterministic (biological sex influences preference).