PSY 320 Health Psychology, Lecture 9 | Source: Lecture slides / exam notes
Difficulty: Intermediate | Prerequisites: Basic understanding of the nervous system and introductory health psychology concepts (Lectures 1 to 8).
This lecture sits at the intersection of biology and psychology, exploring how pain works, why it varies so much between people, and what can be done about it. Pain is one of the central topics in health psychology because it drives health-care-seeking behaviour, influences quality of life, and raises ethical questions around treatment and end-of-life care. You should already be comfortable with basic neuroanatomy (neurons, neurotransmitters, spinal cord pathways) and with the biopsychosocial model from earlier lectures. If those feel shaky, revisit Lectures 1 to 4 before diving in here.
Pain is a subjective, biopsychosocial experience shaped by interpretation, culture, gender, and emotion, not just tissue damage. The gate control theory explains how the spinal cord and brain modulate pain signals, while the body's own endogenous opioid system can suppress them. Chronic pain differs fundamentally from acute pain in its psychology, lifestyle impact, and treatment difficulty, and effective management typically requires an interdisciplinary approach combining pharmacological, surgical, and psychological techniques such as CBT, biofeedback, and relaxation.
Nociception
The sensory process of detecting and transmitting signals about tissue damage. In simple terms, this is how your body registers that something harmful is happening, before any conscious "pain" feeling kicks in.
A-delta fibres
Small, myelinated nerve fibres that respond to mechanical or thermal stimulation and transmit sharp, brief pain signals rapidly. Think of these as the fast lane for acute, localised pain.
C-fibres
Unmyelinated nerve fibres involved in polymodal nociception that transmit dull, aching pain more slowly. These are responsible for that lingering, throbbing pain that follows the initial sharp sting.
Gate control theory
The theory that pain signals can be modulated ("gated") at the spinal cord level before reaching the brain, influenced by both peripheral nerve activity and descending signals from the brain. In simple terms, your spinal cord acts as a gatekeeper that can turn the pain volume up or down.
Periaqueductal grey (PAG)
A region in the midbrain that, when stimulated, produces pain relief by activating descending inhibitory pathways.
Endogenous opioid peptides
Naturally occurring chemicals in the body (e.g. endorphins) that suppress pain. Think of these as your body's built-in painkillers.
Stress-induced analgesia (SIA)
A phenomenon where acute stress temporarily reduces sensitivity to pain, mediated by the release of endogenous opioids.
Acute pain
Pain that results from a specific injury, produces tissue damage, and resolves when the tissue heals. Typically lasts six months or less.
Chronic benign pain
Pain that persists for six months or longer, is relatively unresponsive to treatment, and varies in severity. In simple terms, ongoing pain with no clear end point.
Recurrent acute pain
Intermittent episodes that feel acute in character but recur chronically over more than six months (e.g. migraines).
Chronic progressive pain
Pain that persists beyond six months and worsens over time, typically associated with malignancies or degenerative disorders.
Neurogenic pain
Pain resulting from damage to peripheral nerves or the central nervous system itself, rather than from tissue injury at the pain site.
Psychogenic pain
Pain with no identifiable physical cause, believed to originate from psychological factors.
Pain behaviours
Observable actions arising from chronic pain (guarding, limping, grimacing) that clinicians use to assess how pain has disrupted a patient's life.
Biofeedback
A technique that provides patients with real-time physiological data about a bodily process they are normally unaware of, so they can learn to control it. Used for muscle-tension headaches and migraines.
Cognitive-behavioural therapy (CBT) for pain
A structured psychological approach that teaches patients to break maladaptive behavioural patterns, develop adaptive responses to pain, and attribute improvements to their own efforts.
Minnesota Multiphasic Personality Inventory (MMPI)
A standardised psychological assessment instrument used to develop pain profiles and identify conditions (depression, anxiety, substance use) that increase pain perception.
Pain provides low-level feedback about how our bodily systems are functioning. It is protective: it prompts people to seek treatment and to avoid further injury. Inadequate relief from pain is the most common reason people request euthanasia or assisted suicide, which underlines just how central pain management is to health psychology.
The degree to which pain is felt depends on several factors:
How the person interprets the sensation
The context in which it is experienced (a sports injury on the pitch may barely register in the moment)
Cultural background, as members of some cultures react more intensely to pain than others
Gender differences, with women generally showing greater sensitivity to pain
Pain measurement draws on multiple approaches:
Verbal reports use a large, informal vocabulary ("dull," "shooting," "burning") to capture the qualitative character of pain
Pain questionnaires ask structured questions about the nature and intensity of pain
Psychosocial assessments gauge how much fear pain causes and how far it has taken over a person's life
Methodological tools (e.g. imaging, physiological measures) can provide additional insights
Pain behaviours are observable actions that arise from chronic pain, such as limping, guarding, or avoiding activity. These help clinicians assess disruption and define specific pain syndromes
Pain is a protective mechanism that brings tissue damage into conscious awareness. It is accompanied by motivational and behavioural responses (pulling your hand away from a hot surface, for instance). Negative emotions exacerbate pain, and pain exacerbates negative emotions, creating a feedback loop.
Three kinds of pain perception:
Mechanical nociception results from mechanical damage to body tissues (a cut, a blow)
Thermal nociception is pain caused by temperature exposure (burns, frostbite)
Polymodal nociception involves chemical reactions triggered by tissue damage
This theory transformed our scientific understanding of pain. The key idea is that nociceptors at the injury site sense damage and release chemical messengers to the spinal cord. Whether and how strongly the pain signal reaches the brain depends on a "gating" mechanism in the spinal cord, which can be influenced by other nerve activity and by descending signals from the brain.
The main structures and fibres involved:
A-delta fibres are small, myelinated fibres that respond to mechanical or thermal pain and transmit sharp, brief signals rapidly
C-fibres are unmyelinated and involved in polymodal pain, transmitting dull, aching sensations more slowly
Periaqueductal grey (PAG) is located in the midbrain and produces pain relief when stimulated
The cerebral cortex is involved in cognitive judgments about pain, meaning that what you think and feel about pain changes how intensely you experience it
The body has its own natural pain-suppression system built around endogenous opioid peptides (first demonstrated in early rat studies). These chemicals act on the same receptors that opioid drugs target.
Stress-induced analgesia (SIA) is the phenomenon where acute stress temporarily reduces sensitivity to pain. This is why a soldier in combat or an athlete mid-game may not notice a serious injury until the stress subsides.
Acute pain results from a specific injury, produces tissue damage, and resolves when healing is complete. It typically lasts six months or less.
Chronic pain begins with an acute episode but does not decrease with treatment or the passage of time.
Three kinds of chronic pain:
Chronic benign pain persists for six months or longer, is relatively unresponsive to treatment, and varies in severity
Recurrent acute pain involves intermittent episodes that feel acute but recur chronically for more than six months (migraines are a classic example)
Chronic progressive pain persists beyond six months and gets worse over time, typically linked to malignancies or degenerative disorders
Back pain affects 70 to 85 per cent of Americans at some point in their lives
Headaches affect approximately 45 million Americans chronically
Cancer pain causes moderate to severe pain in the majority of advanced cancer patients
Arthritis pain affects 40 million Americans
Neurogenic pain results from damage to peripheral nerves or the CNS
Psychogenic pain has no identifiable physical cause
Acute and chronic pain have different psychological profiles. Chronic pain carries an overlay of psychological distress that complicates diagnosis and treatment. Patients often develop maladaptive coping strategies, and the interaction of physiological, psychological, social, and behavioural components makes standard pain-control techniques less effective.
Chronic pain can develop through several pathways:
Reacting to a bodily insult with a specific bodily response, which is then exacerbated by stress or by efforts to suppress the pain
High sensitivity to noxious stimulation
Impairment in pain regulatory systems
Psychological distress
Chronic pain is often worsened by inappropriate prior treatments and misdiagnosis or inappropriate prescriptions.
The lifestyle impact is severe. Patients may quit jobs, abandon leisure activities, withdraw from family and friends, require public assistance, and experience a loss of self-esteem. Receiving compensation for pain can paradoxically increase it by providing an incentive for remaining in pain.
Relationships suffer in specific ways: family communication becomes difficult, sexual relationships deteriorate, and positive attention from a spouse may inadvertently maintain the pain.
Behaviourally, patients tend to avoid bright lights and loud noises, reduce physical activity, and shun social contacts. Understanding these pain behaviours, and knowing whether they persist after treatment, is critical to treating the total pain experience.
The idea of a "pain-prone personality" that predisposes someone to chronic pain is too simplistic. Pain itself may produce personality changes, and individual experiences are too complex to capture with a single trait. That said, neuroticism, introversion, and the use of passive coping strategies are all associated with chronic pain.
The MMPI is the main instrument used to develop pain profiles. Conditions that increase pain perception include depression, anger suppression, anxiety disorders, substance use disorders, and other psychiatric problems.
Pain control can mean different things depending on the patient:
An area that once hurt no longer hurts
The person feels sensation but not pain
The person feels pain but is not concerned about it
The person is still hurting but can tolerate it
Pharmacological control is the most common approach. Key drug types include local anaesthetics (which block pain impulse transmission from peripheral receptors to the spinal cord), spinal blocking agents, and antidepressants (which affect descending pathways from the brain that modulate pain). Drawbacks include undesirable side effects and the risk of addiction.
Surgical control aims to disrupt pain conduction from the periphery to the spinal cord or to interrupt pain signals travelling from the spinal cord to the brain. Drawbacks are significant: effects tend to be short-lived, surgery is expensive, and it can damage the nervous system.
Psychological control requires patients to actively participate and learn new skills. It is more effective for managing slow-rising pains than sudden acute episodes.
Psychological approaches include:
Biofeedback provides real-time physiological data about a bodily process the patient is not normally aware of. A target function is identified and tracked by a machine, and the patient attempts to change it with continuous feedback. Effective for muscle-tension headaches and migraines, though it may not outperform cheaper approaches
Relaxation techniques shift the body into a state of low arousal by progressively relaxing different body parts using controlled breathing. The beneficial effects are partly due to the release of endogenous opioids
Distraction turns attention away from pain by focusing on an irrelevant, attention-getting stimulus or engaging in high-level activity. Most effective for low-level pain (commonly used in dental settings)
Coping skills training helps chronic pain patients manage their pain. The expected duration of pain determines which coping strategy a patient should be trained in
CBT for pain management teaches patients to:
Believe that the required skills can be learned
Become competent participants in controlling their own pain
Break up maladaptive behavioural syndromes
Make adaptive responses to pain
Attribute their successes to their own efforts
Practise relapse prevention
Control their emotional responses to pain
Pain management programs are interdisciplinary efforts that bring together neurological, cognitive, behavioural, and psychological expertise. They follow a structured process: initial evaluation followed by individualised treatment. Key components include patient education, involvement of family, and relapse prevention (with relapse rates of 30 to 60 per cent, per Turk and Rudy, 1991).
Students often think pain is purely a physical phenomenon determined by tissue damage. It is not. Pain is a biopsychosocial experience heavily shaped by interpretation, context, culture, and emotion.
Students sometimes confuse A-delta fibres and C-fibres. A-delta fibres are myelinated and fast (sharp pain); C-fibres are unmyelinated and slow (dull, aching pain). Mixing these up is a common exam error.
The "pain-prone personality" idea sounds intuitive but is considered too simplistic. Pain changes personality just as much as personality may predispose someone to pain.
Students often assume that chronic pain is simply acute pain that lasts longer. Chronic pain has a fundamentally different psychological profile, involving maladaptive coping, psychological distress, and social withdrawal.
⚠️ Know the three kinds of chronic pain (benign, recurrent acute, progressive) and be able to distinguish them with examples.
⚠️ Be able to explain the gate control theory in your own words, including the roles of A-delta fibres, C-fibres, and the periaqueductal grey.
⚠️ Understand why chronic pain patients develop maladaptive coping strategies and how lifestyle, relationships, and compensation interact with pain.
⚠️ Be ready to compare pharmacological, surgical, and psychological approaches to pain control, including their respective drawbacks.
⚠️ CBT for pain is a likely exam topic. Know its core principles (breaking maladaptive patterns, self-attribution, relapse prevention).
True or False: C-fibres transmit sharp, rapid pain signals. (False, that is A-delta fibres.)
Fill in the blank: Pain that persists for six months or longer and worsens over time is called __________ pain. (Chronic progressive.)
True or False: The periaqueductal grey is located in the cerebral cortex. (False, it is in the midbrain.)
Fill in the blank: The phenomenon where acute stress reduces pain sensitivity is called __________. (Stress-induced analgesia / SIA.)
True or False: Biofeedback has been shown to be clearly more effective than cheaper relaxation approaches for headaches. (False, it may not be more effective than cheaper approaches.)
Q: What are the three types of chronic pain, and how do they differ?
A: Chronic benign pain persists six months or longer with variable severity and is relatively unresponsive to treatment. Recurrent acute pain involves intermittent acute-like episodes that recur for more than six months (e.g. migraines). Chronic progressive pain persists beyond six months and worsens over time, typically associated with malignancies or degenerative disorders.
Q: Explain how the gate control theory accounts for the psychological modulation of pain.
A: Nociceptors detect injury and send chemical signals to the spinal cord. A gating mechanism in the spinal cord can amplify or dampen these signals before they reach the brain. Descending signals from the cerebral cortex (thoughts, emotions, expectations) influence this gate, which is why cognitive and emotional states can increase or decrease the experience of pain.
Q: Why is distraction more effective for low-level pain than for severe pain?
A: Distraction works by redirecting attention to an irrelevant stimulus or high-level activity. When pain is low-level, this competing stimulus can successfully "win" the attentional competition. Severe pain produces signals too strong to be overridden by attentional redirection alone.
Q: How can receiving compensation for pain paradoxically worsen it?
A: Compensation provides a financial incentive for remaining in pain, which can unconsciously reinforce pain behaviours and reduce motivation for recovery. This is one of several lifestyle factors that complicate chronic pain management.
Q: Compare the drawbacks of pharmacological vs surgical pain control.
A: Pharmacological drawbacks include undesirable side effects and risk of addiction. Surgical drawbacks include short-lived effects, high cost, and the fact that surgery itself damages the nervous system. Both highlight why psychological approaches are an important complement.
This material connects directly to the quality of life and chronic illness content in Lecture 10, where chronic pain is discussed as a major factor compromising patients' daily functioning and psychological wellbeing. The gate control theory's emphasis on cognitive modulation of pain also ties into the stress and coping frameworks covered earlier in the course, since stress both exacerbates pain (via the pain-emotion feedback loop) and can temporarily suppress it (via SIA). The pharmacological content here also sets up the substance use and addiction discussions in broader health psychology.
Pain psychology, nociception, nociceptors, A-delta fibres, A-delta fibers, C-fibres, C-fibers, gate control theory, Melzack and Wall, periaqueductal grey, periaqueductal gray, PAG, endogenous opioids, endorphins, stress-induced analgesia, SIA, acute pain, chronic pain, chronic benign pain, recurrent acute pain, chronic progressive pain, back pain, headache pain, cancer pain, arthritis, neurogenic pain, psychogenic pain, pain behaviours, pain behaviors, pain-prone personality, MMPI, pain profiles, pharmacological pain control, surgical pain control, biofeedback, relaxation techniques, distraction, coping skills training, CBT for pain, cognitive-behavioural therapy pain, pain management programs, health psychology PSY 320