Thesis - Instituto de Telecomunicações

44 CHAPTER 3. INFORMATION SOURCESFigure 3.4: Eccrine sweat gland diagramacronyms) that have been extensively used in the literature are: skin conductance response(SCR) , sympathetic skin response (SSR), galvanic skin response (GSR) and psycho-galvanicreflex (PGR). We will use the term electrodermal activity (EDA) to refer to the phenomenaand skin conductance (SC) to refer to the measurement. We also use the acronym for skinconductance response (SCR) when we refer to the event (some authors use this term torefer to the whole EDA phenomena).To study the Electrodermal activity, the signal is divided into the skin conductancelevel (SCL), and the skin conductance response (SCR). These are normally referred to asthe electrodermal activity tonic and phasic components [146]. The tonic activity is a slowchanging base signal, not directly related to the stimulus. The frequency components ofthe SCL are bellow 0.02 Hz. The phasic component is the result of the activation of thesympathetic system, a faster signal (f