As an indicator of sympathetic nervous system activity and one of the most popular response
systems in psychophysiology, electrodermal activity or EDA has become a widely used
way of operationalizing various psychological constructs including arousal, attention, and stress.
The potential offered by EDA has not gone unnoticed by the HCI community. Its low cost,
relatively unobtrusive form factor, and sensitivity to psychological processes
make it a very attractive element in the user experience toolbelt.
EDA has been used in different areas at CHI such as games, learning, VR, arts, usability, and
interface design and suggest wide applicability and rich potential for use by CHI researchers.
Despite its ostensible simplicity, recording and analyzing EDA signal is a delicate and often
intricate undertaking, involving knowledge from psychology, physiology, and signal processing. The
underlying psychophysiological mechanism of EDA is complex and not well understood, leaving various
factors unnoticed that potentially affect the signal. This context created a severe risk for HCI
researchers to build their research upon a field outside of their expertise, threatening
the validity of their results. Therefore, in our paper a critique of electrodermal activity
practices at CHI, we conducted a systematic review to assess and improve quality of CHI studies
involving the use of electrodermal activity data and derive recommendations for future works.
Our results highlight the concerning issues in different aspects of CHI EDA practices namely
devices, participants and external factors, psychological constructs, pre-treatments
and controls, and analysis. Our result emphasized the dire need for improved community standards
for EDA practices at CHI. The main concerns that our results highlighted are threefold.
First, based on our review it was not always clear whether internal validity had been preserved
as procedure description were often limited. For instance, only a few papers reported details on how
devices were worn and the same issue prevailed in how controls were performed before and during
the studies. Furthermore, several papers in our sample used sites on the skin of which changes
in conductivity are not representative of sympathetic nervous system process.
In addition, many EDA practices at CHI involve intense physical activity which risks EDA
recording quality by destabilizing electrodes and increasing body heat. Second, in terms of
replicability, in several cases, descriptions and methods were not comprehensible due to selective,
incomplete, and non-standard presentation of information. In most papers, we could not
find information on EDA devices, participants' details, procedures, signal processing, and analysis
In addition, violation of standard terminology, using self-defined terms for EDA parameters and
confusion between parameters made understanding papers cumbersome and in some cases impossible
for reader. Third, to ensure high-quality EDA data, different treatments must be applied on the skin
or electrodes prior to the recording and several external factors must be controlled during the
recording. In ambulatory recording used for in-situ studies, some of these steps may be skipped due to
the limited control on participants and their environment. However, laboratory studies should adhere to all
of these steps as much as possible. Although the majority of EDA studies at CHI were conducted in
a lab setting, there is an ongoing trend toward ambulatory recording which affects the choice of
pretreatment, devices, and controls. In addition despite the importance of data preprocessing and
signal parameterization in the analysis of EDA data, we identified a concerning pattern among
the papers in our sample of using raw values directly. The meaningful parts of EDA data are the
phasic and tonic EDA components, so it's necessary to isolate them before analyzing the data.
To leverage community standards for EDA practices we have developed an initial set of guidelines
published at edaguidelines.github.io and invite the community to contribute their
standards and best practices according to various needs that arise in HCI practice and research.
We also recommend reviewers and authors to visit the codebook we developed to assess
EDA studies in our paper and eventually if you want to know more about our review or EDA in
general please visit our paper, A Critique of Electrodermal Activity Practices at CHI.