Physiological Startle Response to Frightening Stimuli in Light and Dark Environment
File(s)
Date
2019Author
Adkins, Breanna
Brennan, Elise
Hoffmann, Hailee
Patel, Krishna
Schmit, Collin
Publisher
Journal of Advanced Student Sciences (JASS)
Metadata
Show full item recordAbstract
Fear is an emotional response that humans experience in situations that are perceived as
dangerous and is accompanied by physiological responses that would protect the body from
potential harm. Different environments, such as darkness, can elicit altered responses in this
physiological change because of the vulnerability and insecurity humans experience when in that
situation. The purpose of our experiment was to determine if there is a significant difference in
the physiological startle response in a dark environment compared to a light environment. We
had 50 students from the UW-Madison Physiology 435 course participate in the study in which
their heart rate (HR), electrodermal activity (EDA), and electromyography (EMG) were
analyzed. They were shown a 2 minute video of ten cards being flipped over one-by-one, and
were told they were performing a memory test. At the 1 minute mark, an emotionally
provocative International Affective Picture System (IAPS) image appeared while paired with a
high-pitched shriek. Participants were randomly selected to watch the video in the dark or in the
light. Since it has been found that humans feel increasingly vulnerable around potentially
threatening stimuli in dark environments, it was hypothesized that the participants who watched
the video in the dark would have a greater startle response than those who watched in the light.
Our results showed that there was no significant difference in heart rate, EDA, and EMG for
participants startled in the dark and light conditions. However, we did find an unexpected
significant difference in masseter EMG between female participants in the light and dark
conditions. Future studies could investigate gender differences as well as a wider, more
randomized population in order to explore different demographics and maintain research
confidentiality. Lastly, our methods could be improved in the future by not allowing subjects to
see the testing room before conducting the study and having the lights off when subjects tested in
the dark enter the room.
Subject
Startle Response
Fear
Heart Rate
Dark
Masseter EMG (electromyography)
IAPS Images (International Affective Picture System)
Electrodermal Activity (EDA)
Permanent Link
http://digital.library.wisc.edu/1793/81996Description
An article that appeared in JASS, issue 2019