Measures of Stress

Biological Measures of Stress

1. Functional Magnetic Resonance Imaging (fMRI)

• Definition: fMRI measures brain activity by tracking the flow of oxygenated blood. Increased blood flow indicates higher activity in the brain areas.

• Application: Used for assessing stress responses during cognitively demanding and stress-inducing tasks.

• Active Areas: Typically includes the amygdala, hippocampus, and hypothalamus.

Example Study: Wang et al (2005)

• Aim: To explore how cerebral blood flow changes under stress during mathematical tasks.

• Procedure:

  • 32 participants were split into stress (25) and control (7) conditions.

  • Participants completed a high-stress mental arithmetic task while in an fMRI scanner, preceded by a low-stress task (counting backwards from 1000).

  • Self-reports of stress and saliva samples for cortisol measurement were collected after each task.

• Results:

  • Regression analyses showed that psychological stress correlates with activation in specific brain regions, notably the ventral right pre-frontal cortex.

• Conclusion: The study signifies the ability to utilize physiological measures in understanding stress responses based on cognitive challenges.

2. Salivary Cortisol

• Definition: Cortisol is a primary stress hormone that can be measured in saliva, indicating levels of physiological stress.

Example Study: Evans and Wener (2007)

• Aim: To assess coping stress levels during commutes by measuring cortisol levels.

• Procedure:

  • 139 urban train commuters were monitored during rush hour, measuring cortisol levels at different time points to evaluate stress.

  • Investigated both the distal crowding (whole carriage density) and proximal crowding (immediate seating).

• Results:

  • Proximal crowding significantly affected cortisol levels and mood, but distal crowding did not.

• Conclusion: Proximal crowding leads to greater individual stress effects than overall density; personal space invasions are more impactful than general crowding.

Psychological Measures of Stress

1. Demand-Control Model

• Tasks that require high mental arousal can increase stress, especially when the control over these demands is low.

• Self-Report Questionnaires:

  • Friedman and Rosenman Personality Test

  • Holmes and Rahe's Life Events Questionnaire

2. SRRS - Holmes & Rahe (1967)

Definition: 43 life events are significant occurrences that disrupt day-to-day activities, influencing stress levels.

Procedure:

• SRRS Development: Based on interviews of 384 individuals, 43 life events were ranked from most to least stressful.

• Measurement: Experiencers quantified their life events for a retrospective 12-month period. Scores over 150 units correlate to increasing chances of stress-related illnesses.

Results:

• Individuals with numerous life changes faced higher illness probabilities:

  • < 150 LCUs: 30% chance

  • 150-299 LCUs: 50% chance

  • 300 LCUs: 80% chance

Conclusion: High life change units correlate positively with health complications due to stress.

Personality and Stress Responses

Example Study: Friedman and Rosenman (1974)

• Aim: Investigate links between Type A behaviour and cardiovascular disease.

• Procedure: 3000 Californian men categorised as Type A or Type B, followed for 8.5 years.

• Results: 70% of those developing CHD were Type A; implies they are more prone to stress-related ailments.

• Conclusion: Type A behaviours increase vulnerability to stress-related illnesses due to factors like hostility and impatience.

Evaluation of Measures

Biological Measures

1. Functional Magnetic Resonance Imaging (fMRI)

   • Strengths:

     • Provides real-time images of brain activity during stress-inducing tasks.

     • Allows for the identification of specific brain regions associated with stress responses (e.g., amygdala, hippocampus).

     • Objective measurement of physiological reactions to stress.

   • Weaknesses:

     • Expensive and requires specialized equipment.

     • Results can be influenced by external factors and individual differences.

     • Limited to understanding brain activity and may not account for other physiological changes.

2. Salivary Cortisol

   • Strengths:

     • Non-invasive method of measuring stress hormone levels.

     • Directly correlates with physiological stress responses.

     • Useful in real-life settings (e.g., during commutes).

   • Weaknesses:

     • Cortisol levels can fluctuate due to various factors unrelated to stress (e.g., time of day, illness).

     • May not capture the full complexity of an individual's stress experience.

Psychological Measures

1. Demand-Control Model

   • Strengths:

     • Helps to explain the relationship between work stress and control over demands.

     • Highlights the importance of perceived control in managing stress levels.

   • Weaknesses:

     • Lacks objective measures and relies heavily on self-reported data.

     • Subjective interpretations of demands and control can vary between individuals.

2. Life Events - Holmes & Rahe (1967)

   • Strengths:

     • Provides a framework for understanding how major life changes impact health.

     • Empirical basis with quantitative scoring system (LCUs).

   • Weaknesses:

     • May oversimplify stress responses by focusing on life events without considering context or individual differences.

     • Retrospective nature may lead to recall bias.

3. Friedman and Rosenman Personality Test

   • Strengths:

     • Links personality types to stress vulnerability, aiding in counselling and interventions.

     • Validates the impact of personality on health outcomes.

   • Weaknesses:

     • Typing individuals as Type A or Type B may overlook complexities of personality.

     • Potential stigma against individuals deemed Type A as more aggressive or hostile.