Allgemeine und Biologische Psychologie

skin conductance

Suppose somebody is standing behind you and claps loudly in their hands without warning. Surely you will startle. Evolution has prepared us to react effectively in such situations. Regardless of whether we decide to fight or flight, we should immediately prepare ourselves to act. This will most probably involve our hands, grasping a club to defend ourselves, or climbing a tree to evade an aggressor. Our palm features specialized sweat glands that are intended not to wet the surface of the palm but to moisten the epidermis internally, giving the hand more grip and making its skin less vulnerable.

The activity of these sweat glands can be measured be applying a low voltage and measuring the current that passes through the skin. The conductance of the skin, i.e. the ability to let current pass through it, increases in case of arousal due to the activity of these specialized sweat glands. The reaction of the skin is conveyed via the sympathetic nerve system, and it is more or less instantaneously. Due to the slow diffusion processes of the sweat moistening the epidermis and its subsequent evaporating, the raw data of the skin conductance are much less temporally confined. Using a sophisticated deconvolution algorithm we are able to reconstruct the temporally confined answer of the sympathetic nerve system (see www.ledalab.de).

Benedek, M., Kaernbach, C. (2010). Decomposition of skin conductance data by means of nonnegative deconvolution. Psychophysiology 47, 647-658.

 

Palmar Sweat gland. Adapted from Boucsein, W. (1976).           Illustration of deconvolution of skin conductance data.
Electrodermal activity. Springer, Boston                                       Adapted from Benedek & Kaernbach (2010), Fig. 3.
sweat gland                                                               skin conductance graph