Measuring Stress - Skin conductance response (SCR) Flashcards
Skin Conductance Response
Immediate stress is related to sympathetic arousal of the autonomic nervous system, resulting in the production of adrenaline and noradrenaline, which cause a number of physiological responses e.g. increased heart and breathing rates, blood pressure and sweating.
Skin is electrically active and the sweat created from the body’s response to stress increases the skin’s ability to conduct electricity, which is known as the skin conductance response. This effect is strongest in the hands and soles of the feet because of the high density of sweat glands at these points.
Individuals have a higher skin conductance response (SCR) when stressed. SCR readings need to be taken in stressed and non-stressed states so that comparisons can be made.
How is it used?
Two electrodes are placed on a person’s index and middle finger. A very small voltage (0.5V) is applied across these electrodes. By measuring the current that flows between them, conductance can be reported.
SCR readings are measured through use of a polygraph:
This is a machine that records physiological measures, including skin conductance response.
The use of a polygraph involves an individual sitting quietly for around 30 minutes so that a baseline score can be established to which readings are compared when the individual is stressed
Villarejo et al. (2012) procedure
Villarejo et al. (2012) used a computer-operated stress sensor to measure stress levels in 16 adult participants, who were required to complete tests involving different levels of stress, for instance, being relaxed, solving mathematical tests and exposure to anxiety-creating stimuli.
Villarejo et al. (2012) findings
It was found that skin conductance response readings were able to detect participants’ different stress levels with a success rate of 76.5%.
Villarejo et al. (2012) supports
This supports the idea of skin conductance response being a capable, though not perfect, method of measuring stress levels.
Skin conductance response allows for stress to be measured in an objective way, avoiding some of the problems associated with self-report measures (e.g. social desirability bias).
Readings can be combined with recordings of heart rate, respiratory rate and blood pressure.
They can also be used continuously throughout research and go relatively unnoticed by participants.
They are easy to perform and relatively low cost.
Non-specific response: However, SCR measures sympathetic arousal, which occurs in response to any emotion (e.g. fear, anger, surprise, sexual arousal), not just stress.
Research by Khalfa et al. (2002) supports this argument
They played different types of music to arouse emotions of fear, happiness, sadness and peacefulness in participants and measured their reactions using skin conductance response readings.
Skin conductance response readings were found to be the greatest for the emotions of fear and happiness.
This suggests that skin conductance response readings can measure stress levels (as portrayed through fear), but cannot differentiate stress from other completely different emotional reactions such as happiness.
SCR has been criticised for being unreliable because….
SCR measurements can be affected by external factors (e.g. temperature and humidity), which could lead to inconsistent readings. It can also be affected by internal factors (e.g. medications and alcohol).
Responses can be inconsistent even with the same stimulus levels and can vary from one day to another for the same person, again illustrating their lack of reliability in measuring stress levels.
Research also suggests that the physiological response can be affected by cognitive perception.
For example, changes in skin conductance have been observed depending on whether a person feels they have been treated fairly or not.
Thus, physiological measurements only tell us part of the story – they cannot provide information as to how a stressor has been perceived.
Research suggests that SCR is also not a very reliable measure of deceitfulness
Oshumi and Ohira (2010) found that psychopaths show a general lack of emotional responsiveness, meaning that they can lie without any associated physiological response. Therefore, SCR measurements would reveal very little, if anything, about the individual’s stress levels and would not be a very dependable measure of deceitfulness.
