<!-- TITLE: Electrodermal activity --> <!-- SUBTITLE: Getting a pulse on our lizard brain --> Most of this information came from [Figner and Murphy (2010)](https://www.researchgate.net/publication/228888313_Using_skin_conductance_in_judgment_and_decision_making_research).   + skin conductance (SC) *indicates* autonomic nervous system (ANS) activity + the ANS does a lot, so SC indicates a lot + cheap, noninvasive, time domain of a few seconds > Interesting, the author cites an *emotions revolution* (Weber & Johnson, 2009) in neuroscience, which popularized a specific type of EDA: skin conductance. + SC reflects hidden processes affecting decision-making + SC is tricky, and there are some subtleties # Terminology + **electrodermal activity (EDA)** measures electrical properties of the skin + **endosomatic** = not using external current + **exosomatic** = using external current (e.g. SC) > Measures of EDA quantify electrical properties of the skin + **skin conductance (SC)** - DC - voltage held constant + **skin resistant** - DC - current held constant + **skin admittance** - AC - effective voltage held constant + **skin impedance** - AC - effective current held constant *** + SC measured in **microsiemens** ($\mu S$) + **skin conductance level (SCL)** - the average trend of SC over minutes or 10s of minutes - indicates arousal + **skin conductance response (SCR)** - SC peak and fall lasting a few seconds - responds to events - "phasic" + **tonic skin conductance (TSC?)** - number of SCRs per minute *** + **onset latency** - time from stimulus to SCR + **rise time** - time between onset and max amplitude + **amplitude** - SC at max minus SC at onset + **area bounded by curve of SCR** - a more recent measure of the magnitude of an SCR # Process interpretation + SC changes are caused by sweating! + "sympathetic branch of ANS controls sweathing" `thus??` "skin conductance reflects 'arousal' of the sympathetic ANS" + ANS is in hypothalamus and brainstem, but other parts of limbic and paralimbic networks are involved + the "Iowa group" + demonstrated SCL indicates affective processing before, during, and after making decisions + showed that SCL indicates expected affect + Reid and Gonzalez-Vallejo (2009) + showed that relative magnitude of SCRs is predictive of preferences + Krosch, Figner, & Weber + used SCL to show something about "the CCT" (`???`) # Doing experiments + **equipment** Biopac system, with SC and cardiovascular activity modules + **software** (AcqKnowledge) that comes with it enables analysis + author gives his whole set-up, down to each parameter - *skip* *** + deep breaths give clear SCRs, and indicates the system is working + because of SC's long latency, they used to long inter-stimulus periods, to let SC respond + *until* **rapid event-related designs** -- allow SC responses to overlap, as in BOLD, [deconvolving statistically](https://en.wikipedia.org/wiki/Deconvolution) # Other resources + emotion etc... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2756702/ + amazing emotion sociology: thomas scheff, microsociology!! + [Analytic measures for quantification of arousal from spontaneous skin conductance fluctuations](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2877802/) + [Interpersonal autonomic physiology](https://journals.sagepub.com/doi/10.1177/1088868316628405?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed)