Galvanic Skin Response (21/10/13 lab)

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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.

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