The Galvanic Skin Response (21/10/13 prac)

The electrical properties of the surface tissues (skin and connective tissue) are influenced by the amount of blood flow in the tissue and also the activity of the sweat glands found there – both of these are influenced by autonomic activity, which in turn is affected by one’s emotional state:

Emotional state

affects

Autonomic nervous activity

affects

Smooth muscle control of blood supply to and sweat glands in the skin

affects

The electrical properties of the skin

We do not have conscious feedback from our ANS and so we do not have much conscious control over it. However, its operation can be affected by the way we are interacting with our external environment – particularly by our emotional state.

We explored this response by attaching electrodes to the underside of the index and middle fingers on the subject’s non-dominant hand. The electrodes were attached to a Biopac which monitored the electrical properties of the skin. Subjects were shown a slideshow of ‘neutral’ and ‘distressing’ images, ranging from furniture to starvation, and were asked to both announce when the image had appeared (so that any changes noted on the monitor could be attributed to the appropriate slide) and rate the slides from 1 (very distressing) to 5 (fine). The results consisted of both the area shown on the Biopac data and the score given by the subject.

My results were not consistent. The areas on the Biopac reading varied even when I had scored an image in the same way, and the areas did not increase properly towards the most distressing images. The experimental conditions were fairly relaxed and I was talking and joking with friends beforehand, which likely had an impact on the results. Further, I wonder if different emotions have different responses – for instance, some images made me feel repulsed, others shocked, and others sad.

The Galvanic skin response is one aspect of polygraph tests, which are used in psychological and legal settings. Supposedly, they can show if a person is lying because autonomic nervous activity cannot be consciously controlled – however, a person must have an autonomic response to a lie in order for it to be measured (for instance, psychopaths do not) and external conditions such as room temperature can affect the response. Further, there is a 1-3 second delay in Galvanic responses.

	Created by sophietevans almost 11 years ago

The physiological basis, methodology, result interpretation, and clinical relevance of the Galvanic skin response, from the 21/10/13 Human Physiology lab.

Galvanic Skin Response (21/10/13 lab)