Pain is classified by origin (organic vs. psychogenic), duration (acute vs. chronic), and location (referred, clinical). The gate control theory is the dominant model for understanding how pain signals reach the brain. Cultural and gender differences shape both pain experience and treatment. The biopsychosocial model ties the entire course together: health is biological, psychological, and social.
Difficulty: Intermediate | Prerequisites: Basic neuroscience concepts (nerve fibres, spinal cord), biopsychosocial model
This chapter introduces the psychology of pain, covering what pain is, how it works physiologically (gate control theory), and how psychological and social factors modify the experience. Gender socialisation, cultural norms, and racial disparities in pain treatment are all examined. The chapter also serves as a bridge to the broad themes that run through the entire exam: the biopsychosocial model, social support, social determinants of health, and the health onion (multi-level thinking). If you understand how this chapter connects to every other topic, you are well positioned for the exam.
Organic pain
Pain linked to tissue pressure or damage. There is a physical cause you could point to.
Psychogenic pain
Pain without an organic basis. For example, pain perceived by a person with schizophrenia. Both types hurt equally; psychogenic pain is not less important than organic pain.
Acute pain
Short-term pain with a clear onset and expected resolution.
Chronic pain
Long-term, unending pain. Three subtypes: chronic-recurrent (repeated intense episodes from a benign cause), chronic-intractable-benign (constant pain not related to a malignant condition, e.g. low back pain), and chronic-progressive (continuous pain from a progressive disease, e.g. cancer or rheumatoid arthritis, worsening over time).
Referred pain
Pain felt in a different part of the body from its actual source. A classic example: heart attack pain felt in the left arm.
Clinical pain
Pain that requires professional treatment.
Nociceptors
Sensation receptors of various types, each sensing something different (heat, pressure, chemicals). Located throughout the body.
Afferent nerves
Nerves that send signals from the periphery of the body to the spinal cord and brain. Think of them as the "incoming" lines.
Efferent nerves
Nerves descending from the brain that can send signals regarding pain and can close the gate interneurons. Think of them as the "outgoing" lines.
A-beta fibres
Large-diameter, myelinated nerve fibres that transmit impulses to the brain quickly. These are touch nerves that sense cold, heat, and other non-painful stimuli.
C fibres
Smaller, unmyelinated nerve fibres with slower transmission. Carry information about diffuse, dull pain.
A-delta fibres
Similar to C fibres but transmit sharp pain quickly.
Gate interneurons
A hypothetical "gate" in the spinal cord. When large fibres (A-beta) send signals, inhibitory neurons are excited and the gate closes, blocking pain signals. When small fibres (C, A-delta) send signals, inhibitory neurons are impeded and the gate opens, allowing pain signals through.
Locus of control
The degree to which a person feels they have control over what happens in their life versus attributing outcomes to external forces. Low locus of control is associated with worse pain outcomes.
Catastrophising
Having frequent, negative thoughts about a situation. In pain contexts, this amplifies the pain experience.
Secondary gains
Benefits that come from being sick, such as attention, sympathy, or exemption from responsibilities.
Organic pain: Linked to tissue pressure or damage.
Psychogenic pain: No organic basis. Both types hurt equally.
Acute: Short-term, clear onset.
Chronic: Long-term, further divided into:
Chronic-recurrent: Repeated, intense episodes from a benign cause.
Chronic-intractable-benign: Constant pain (sometimes varying in intensity) not related to a malignant condition. Low back pain is the classic example.
Chronic-progressive: Continuous pain from a progressive disease (cancer, rheumatoid arthritis). Worsens as the underlying condition progresses.
Referred pain: Felt in a different part of the body from its source.
Clinical pain: Pain requiring professional treatment.
Girls are socialised to express pain as needed, and this is sometimes reinforced by caregivers.
Boys are taught not to admit pain, discomfort, or weakness.
The result: females report more pain, but their pain is more greatly discounted by providers.
African Americans and Latinos receive less pain treatment overall.
African Americans and Hispanics are more afraid of opioid addiction and less likely to misuse prescription opioids.
Non-white patients receive fewer and smaller doses of pain medication.
Minority and low-income children are less likely to have oral pain assessed and treated appropriately.
Research has shown that African Americans have the lowest pain tolerance among racial groups studied. This is a finding about pain tolerance (the amount of pain someone can endure), not pain threshold (the point at which a sensation becomes painful), which is similar across groups.
Pain produces facial or audible expressions of discomfort, distorted movements or postures, negative affect, and avoidance of activity.
Being sick sometimes comes with benefits: attention, reduced responsibilities, sympathy. These gains can reinforce pain behaviour.
Children whose parents paid more attention to them when in pain reported greater pain. Children also observe how others deal with pain, and families reinforce particular pain behaviours.
Pain coping tends to be emotion-focused rather than problem-focused.
Overt behavioural coping: Getting rest, using relaxation techniques, taking medications.
Covert coping: Hoping, praying, self-distraction.
Neither is particularly effective at reducing pain.
People who cope well with pain tend to show pain acceptance: acknowledging pain without excessive struggle against it.
How you think about pain changes how you perceive it.
Locus of control: People who feel they have control over their lives cope better with pain. Low locus of control is associated with worse outcomes.
Catastrophising: Frequent, negative thoughts about a situation amplify the pain experience.
Proposes a direct relationship between pain stimulus and pain experience: more stimulus equals more pain. Simple but does not account for psychological modulation.
People are conditioned to expect pain based on prior experiences. Past encounters with pain shape future pain perception.
Biological traits (diatheses) can interact with stressors in a person's environment to cause illness and pain. This model bridges biology and psychology.
The dominant model for understanding pain. The core idea: a hypothetical "gate" in the spinal cord determines whether pain signals reach the brain.
The players:
Nociceptors: Sensation receptors located throughout the body.
Afferent nerves: Carry signals from the body to the spinal cord and brain.
Efferent nerves: Descend from the brain and can close the gate.
A-beta fibres: Large, myelinated, fast. Sense touch, cold, heat.
C fibres: Small, unmyelinated, slow. Carry diffuse, dull pain.
A-delta fibres: Similar to C fibres but carry sharp pain quickly.
How the gate works:
Sharp, brief pains: A-beta fibres are activated and send messages to the brain quickly. They excite the inhibitory interneurons, which close the gate and end the pain experience.
Slow, aching, burning pains: C or A-delta fibres are activated. They inhibit the interneurons from closing, so the gate stays open and pain signals continue reaching the brain.
Large fibre activity > pain fibre activity: When large fibre activity outweighs small fibre activity, people experience less pain because the gate closes. This explains why rubbing an injury helps: it stimulates large A-beta fibres.
Small fibre dominance: When small pain fibres dominate, the inhibitory neurons cannot keep the gate closed, and pain information travels to the brain freely.
Additional gate closure mechanisms:
Counterirritation (applying a competing stimulus).
Efferent pathways (signals from the brain that close the gate).
Stress, anxiety, and depression can also influence pain by affecting gate function.
This model underpins the entire course. Every topic on the exam can be understood through its three components:
Biological: Physical factors such as diseases, injury, genetics, and physiological processes. Pain is felt in the body; cancer involves cell mutation; heart disease involves arterial damage.
Psychological: The level, intensity, and duration of what we feel is shaped by our thoughts, expectations, and mental state. Phantom pain (pain without a physical cause) is a clear example. Optimism, catastrophising, and locus of control all operate here.
Social: How we experience health and illness is shaped by the family we grew up in, the culture we come from, and the support we receive. Social support, stigma, discrimination, and SES all fall under this component.
Social support appears as a protective factor in every chapter: it delays cancer progression, supports cardiac rehabilitation, helps manage HIV/AIDS, and modifies pain experience. Illness and stigma can erode social support, creating a feedback loop that worsens outcomes.
Health outcomes are determined by multiple nested layers: individual biology, individual psychology, interpersonal relationships, community factors, and societal structures. This "onion" model reminds you not to reduce health to any single level.
Health follows a gradient: the higher a person's socioeconomic position, the better their health tends to be. This gradient is not just about poverty versus wealth; it operates at every step of the socioeconomic ladder. Access to care, health literacy, environmental exposures, and chronic stress all mediate this relationship.
Students often dismiss psychogenic pain as "not real." Both organic and psychogenic pain hurt equally. Psychogenic pain is not less important.
The gate control theory is sometimes misunderstood as literal. There is no physical gate in the spinal cord; the "gate" is a metaphor for the inhibitory mechanism that modulates pain signals.
Many students confuse pain threshold (the point at which a sensation becomes painful, similar across people) with pain tolerance (how much pain someone can endure, which varies widely).
Emotion-focused coping (hoping, praying, distraction) is sometimes assumed to be effective for pain. The evidence suggests it is not particularly effective at reducing pain.
⚠️ Gate control theory is the most heavily tested pain topic. Know the fibre types (A-beta, C, A-delta), how the gate opens and closes, and why rubbing an injury helps.
⚠️ Be able to distinguish organic from psychogenic, acute from chronic, and the three subtypes of chronic pain.
⚠️ Racial disparities in pain treatment (African Americans and Latinos receiving less treatment) are commonly tested.
⚠️ The biopsychosocial model is the framework for the entire exam. Be able to apply it to any topic.
⚠️ Know the difference between pain threshold and pain tolerance.
⚠️ Social determinants of health and the health gradient are broad themes that could appear in any question.
True or False: Psychogenic pain is less real than organic pain. (False. Both types hurt equally.)
Fill in the blank: In gate control theory, _______ fibres are large, myelinated, and close the gate when activated. (A-beta)
True or False: Pain threshold varies widely between individuals. (False. Pain threshold is similar across people; pain tolerance is what varies.)
Fill in the blank: The three subtypes of chronic pain are chronic-recurrent, chronic-intractable-benign, and _______. (Chronic-progressive)
True or False: Emotion-focused coping (praying, hoping, distraction) is highly effective at reducing pain. (False.)
Q: A patient stubs their toe and feels sharp pain that fades quickly. Using gate control theory, explain why.
A: The sharp pain activates A-beta fibres, which are large and myelinated. They send signals to the brain quickly and excite the inhibitory interneurons, which close the gate and end the pain experience.
Q: A patient has constant low back pain that varies in intensity but is not related to a progressive disease. What type of chronic pain is this?
A: Chronic-intractable-benign pain.
Q: Why might an African American patient receive less pain medication than a white patient presenting with the same condition?
A: Racial disparities in pain treatment are well documented. Non-white patients receive fewer and smaller doses of pain medication, influenced by provider assumptions and systemic biases.
Q: Apply the biopsychosocial model to the experience of chronic pain.
A: Biological: the tissue damage or nerve dysfunction causing the pain signals. Psychological: thoughts, expectations, catastrophising, and locus of control that shape how the pain is experienced. Social: family responses to pain behaviour, cultural norms about expressing pain, and access to treatment.
Q: What is the health gradient?
A: The pattern in which health improves at every step up the socioeconomic ladder. It is not simply about being poor vs. wealthy; each incremental increase in socioeconomic position is associated with better health.
Gate control theory's mechanism (where psychological states modulate physical signals) parallels the PNI framework in the HIV/AIDS chapter. Cultural disparities in pain treatment echo the patterns in every other chapter. The biopsychosocial model is the thread that connects patient-provider communication, cancer, heart disease, HIV/AIDS, and pain into a single coherent framework.
pain types, organic pain, psychogenic pain, acute pain, chronic pain, chronic-recurrent, chronic-intractable-benign, chronic-progressive, referred pain, clinical pain, gate control theory, nociceptors, afferent nerves, efferent nerves, A-beta fibres, C fibres, A-delta fibres, gate interneurons, specificity theory, cognitive-behavioural model, diathesis-stress model, locus of control, catastrophising, secondary gains, pain acceptance, biopsychosocial model, social determinants of health, health gradient, health onion, social support, PSY 320, health psychology