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Every claim in this option — that stress suppresses immunity, that low control damages the heart, that daily hassles predict ill health — depends on one thing: the ability to measure stress accurately. But stress is a peculiarly difficult thing to measure, because it has both a psychological dimension (how stressed a person feels and what they appraise as threatening) and a physiological dimension (the bodily activity of the SAM pathway and the HPA axis). Psychologists have therefore developed two broad families of measurement: self-report scales, which ask people directly about their stressors and feelings, and physiological measures, which record the body's stress response objectively. This lesson examines the main techniques in each family — including the Social Readjustment Rating Scale, the Hassles and Uplifts Scale, the skin conductance response, heart rate, and cortisol measured in saliva or blood — and weighs the strengths and limitations of each. The recurring theme is a trade-off: self-report is rich but subjective, while physiological measures are objective but say nothing about meaning.
Key Definition: Self-report measures of stress are questionnaires and scales on which people describe their own stressors and stress experience. Physiological measures of stress are objective recordings of the body's stress response, such as heart rate, the skin conductance response, and levels of stress hormones.
The central insight of this lesson is that no single measure captures stress completely. Because the psychological and physiological aspects of stress do not always correlate, the most valid research often combines self-report with physiological measurement — a methodological lesson that applies far beyond stress.
This lesson addresses the following points in AQA A-Level Psychology (7182), Paper 3, Section C (Stress):
Assessment objectives engaged: AO1 (knowledge of self-report and physiological methods of measuring stress and how each works), AO3 (evaluation of the strengths and limitations of each approach — objectivity, validity, reliability, practicality, and the problem of subjective versus physiological measures), and — where a question contains a scenario — AO2 (selecting or applying an appropriate measure to a described situation). This lesson is strongly synoptic with Paper 2 Research methods.
Self-report scales ask people to describe their own stressors or stress experience, usually through a structured questionnaire that yields a numerical score. Two were introduced in the Life Changes and Daily Hassles lesson and are revisited here from a measurement perspective.
The SRRS (Holmes & Rahe, 1967) measures stress indirectly, by quantifying a person's exposure to major life changes. Respondents indicate which of 43 life events they have experienced in a given period; each event carries a weighting in life change units (LCUs) (death of a spouse = 100, divorce = 73, marriage = 50), and the units are summed to give a total that is taken to index the person's recent stress exposure. The SRRS therefore measures stressors rather than the stress response itself, on the assumption that more life change means more stress.
The Hassles and Uplifts Scale (Kanner et al., 1981) measures exposure to the minor, everyday stressors (hassles) and minor positive events (uplifts) of daily life. Respondents indicate which hassles and uplifts they have experienced recently and rate their severity or pleasantness. Like the SRRS, it measures sources of stress, but it captures the chronic, low-level daily stressors that the SRRS misses, and (as DeLongis et al., 1982, found) it often predicts health better.
A general advantage of well-designed self-report scales is that they are standardised: every respondent answers the same fixed items in the same way, which makes scores directly comparable between people and across studies, and allows the scale's reliability and validity to be formally assessed. This standardisation is part of what makes self-report scales scientifically useful despite their subjectivity. Their limitation, however, is that the meaning a respondent attaches to each item still varies — the same "argument with a partner" hassle may be trivial for one person and devastating for another — so even a standardised scale cannot fully capture the individual appraisal that determines stress.
Both scales share the features — and the problems — of all self-report measures:
| Property | Self-report scales (SRRS, HSUP) |
|---|---|
| What is measured | Exposure to stressors (life events / daily hassles), indirectly indexing stress |
| Data type | Quantitative scores, easy to compare and correlate |
| Practicality | Quick, cheap, non-invasive; can survey large samples |
| Key weakness | Subjective and retrospective; relies on honest, accurate recall; ignores individual appraisal of the same event |
Key Definition: The skin conductance response (SCR) — also called galvanic skin response or electrodermal activity — is a physiological measure of stress and arousal based on changes in the electrical conductivity of the skin caused by sweat-gland activity, which is controlled by the sympathetic nervous system.
Physiological measures bypass self-report and record the body's stress response directly. They are based on the physiology studied in the first lesson: the SAM pathway raises heart rate, blood pressure, and sweating, while the HPA axis raises cortisol, so each of these can serve as an objective index of stress.
When the sympathetic nervous system is activated by stress, the sweat glands become more active. Even tiny increases in sweat raise the electrical conductivity of the skin, because sweat (being salty) conducts electricity. The skin conductance response measures this by passing a small, imperceptible current between two electrodes placed on the fingers or palm and recording changes in conductance. A larger or more frequent skin conductance response indicates greater sympathetic arousal and therefore greater stress. Because the response is driven by the sympathetic nervous system and is not under voluntary control, it provides a sensitive, real-time, objective index of arousal — which is also why it is a component of the polygraph ("lie detector").
Stress raises heart rate and blood pressure through sympathetic activation and adrenaline. Both can be measured easily and non-invasively (a heart-rate monitor or blood-pressure cuff), and both rise in real time during acute stress, making them convenient continuous measures of the cardiovascular component of the stress response. They are widely used in laboratory stress studies because they respond instantly to a stressor and recover as it passes. A more sophisticated cardiovascular index is heart-rate variability (HRV) — the variation in time between successive heartbeats. Counter-intuitively, higher variability indicates a relaxed, parasympathetically dominated state, whereas reduced variability is associated with stress and sustained sympathetic activation, so HRV is increasingly used as a sensitive marker of stress and recovery, particularly in wearable devices.
Because cortisol is the central hormone of the chronic stress response (the output of the HPA axis), measuring it provides a direct index of HPA activity. Cortisol can be assayed from a blood sample or, more conveniently and non-invasively, from a saliva sample. Salivary cortisol is especially useful because samples can be collected repeatedly throughout the day (for example, to track the natural morning peak or the response to a stressor) without the stress of a blood draw — important, since the act of taking blood can itself raise cortisol and confound the measurement. Cortisol is the measure of choice for studying chronic and prolonged stress, complementing the heart-rate and skin-conductance measures that best capture acute arousal.
The main physiological measures are summarised below.
| Measure | What it indexes | Captures best |
|---|---|---|
| Skin conductance response | Sympathetic arousal (sweat-gland activity) | Acute arousal, real-time |
| Heart rate / blood pressure | Cardiovascular sympathetic activation | Acute stress, continuous |
| Salivary / blood cortisol | HPA-axis activity (the chronic stress hormone) | Chronic / prolonged stress |
A practical refinement worth knowing is ambulatory monitoring — using portable devices (such as a 24-hour blood-pressure monitor or a wearable heart-rate sensor) to record physiological measures continuously while the person goes about their ordinary life. This raises the ecological validity of physiological measurement, because it captures the stress response in real settings rather than only in an artificial laboratory, and it allows researchers to link physiological spikes to real events (a difficult meeting, a commute). It is increasingly important as wearable technology becomes widespread.
The quality of any measure is judged on two criteria from research methods, and stress measurement illustrates both especially clearly:
This reliability–validity distinction is the analytical backbone of the evaluation that follows, and using the terms precisely is a strong discriminator in exam answers.
The fundamental contrast is between objectivity and meaning. Physiological measures are objective and quantitative but cannot tell you what the person is stressed about or whether they are stressed at all rather than simply aroused by exercise, caffeine, or excitement — physiological arousal is not specific to stress. Self-report captures the subjective, appraised experience of stress but is vulnerable to bias and may not correspond to what the body is actually doing. The table below sets out the trade-off.
| Dimension | Self-report scales | Physiological measures |
|---|---|---|
| Objectivity | Low — subjective, open to bias | High — objective, hard to fake |
| Validity (meaning) | Captures appraised, subjective stress | Captures arousal but not its meaning/cause |
| Reliability | Variable; depends on recall and honesty | Generally high and replicable |
| Practicality | Quick, cheap, large samples | Often needs equipment; some are invasive |
| Specificity to stress | Asks specifically about stress | Arousal may have non-stress causes |
The clear methodological conclusion is that the two approaches are complementary, not rivals: the most valid stress research (such as Johansson's sawmill study, which combined hormonal assays with records of illness) uses physiological and self-report measures together, so that objective arousal can be interpreted in the light of the person's subjective experience.
To see how this works in practice, imagine a study of exam stress in students. A researcher might (a) administer a self-report stress questionnaire to capture how stressed each student feels, (b) collect salivary cortisol samples across the exam period to index HPA activity, and (c) record heart rate during a mock exam to capture acute arousal. If a student reports high stress and shows raised cortisol and heart rate, the converging evidence is compelling. But the design also reveals the interesting cases: a student who reports feeling calm yet shows high cortisol may be unaware of or suppressing their stress, while one who reports panic but shows little physiological change may be experiencing anxiety that is more cognitive than physiological. Neither pattern would be visible using a single measure. This is exactly why methodologically strong stress research triangulates — using multiple measures so that the strengths of one compensate for the weaknesses of another.
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