Electrodermal Activity Flashcards
Who were the first researchers to make observations on EDA?
What two basic methods did they contribute to?
Fere: 1888 observed changes in electrical activity of skin can be produced by physical and emotional stimuli
Tarchanoff made same observation at similar time
(1st person actually vigouroux according to Bouscein)
Skin conductance and skin potential
What were the differences in Fere and Tarchanoff’s techniques?
- Fere passed small current between two electrodes on surface (galvanometer used to detect change in SCL)
- Tarchanoff used no external applied current because there are already natural different in potential between two areas of skin
What are the two main layers of skin and what are they made up of?
- Epidermis- outer layer, 5 cellular layers
- Dermis- inner layer, contains: hair follicles & sweat glands
ALSO Hypodermis- just below dermis (contains secretory portions of sweat glands)
What is the distribution and make up of eccrine glands?
Wide distribution over body (unlike apocrine). Most on palms and soles. Simple tubular structure with duct leading to surface. Secretory portion (coils into ball) opens as pore.
How many sweat glands does the body contain?
could range from 2-5million
Where do eccrine glands nerve supply come from?
Secretory portion has nerve supply via cholinergic fibres of SNS but transmitted by acetylcholine (usually assoc with PNS)
How does the skin help maintain warmth?
Constriction of blood vessels and philoerection.
What are the differences between phasic and tonic responses?
Phasic responses are momentary, occur from stimulation. Tonic levels are relatively stable.
What types of EDA relate to the Fere effect and why?
SRR, SRL, SCR, SCl- they rely on external sources of current for observation (exosomatic)
What types of EDA relate to Tarchanoff effect?
SPR, SPL (endosomatic) don’t need external current (difference in potential of two diff areas of skin can be measured)
What is the traditional unit of conductance and what is more regularly used now?
Trad= mho (ohm=unit resistance) Now= microsiemen(us) identical to umho)
What is the range of SCR change?
SCR phasic change can vary 0.05umho-5umho
What are the two basic circuits used to measure SCL?
constant voltage: holds voltage across electrodes constant (skin varies with conductance change- ink writer)
Constant current: potential diff between electrodes varies with resistance
What is skin potential measured in?
millivolts (mv) can be biphasic or uniphasic
How is SPL/SPR measured?
unipolar placement of electrodes, mental stimulation to produce change. Measured with a sensitive DC amplifier, active electrode and reference electrode (inactive electrode placed on abraded skin)
