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In the current study, juvenile twins aged 9-13 were asked to perform two psychophysiological tasks, referred to as the carbon dioxide (CO2) challenge and the Screaming Lady task. In the CO2 challenge, participants were asked to breathe enriched air for eight minutes that contained 7.5% CO2 for. Subjective anxiety was assessed every two minutes during a baseline, CO2 inhalation, and recovery period using the subjective units of distress scale (SUDS). The Screaming Lady task was designed to assess a fear-potentiated startle response. Participants were exposed to a classical conditioning paradigm in which loud screams were paired with images of a woman’s face. Air puffs delivered to the forehead were used to induce a startle response, and participants were unaware of when either stimulus (scream or air puff) would be administered. A SUDS rating was taking before the Screaming Lady task began, after the acquisition period, and after the extinction period. Based on previous research, it has been shown that sustained inhalation of CO2 can trigger physical symptoms similar to those experienced during a panic attack (Blue, 2014). In the current study, the CO2 and Screaming Lady tasks were also administered one after the other though the order of what came first was randomized. It is hypothesized that the anxiety generated by the CO2 task could lead to greater distress and anxiety during the Screaming Lady task. This would be demonstrated by higher SUDS ratings during the Screaming Lady task by those who did the CO2 task first. The data was divided in two parts: one in which the carbon dioxide task was performed before the screaming lady task and one in which the screaming lady task was performed first. The SUDS ratings will be used to examine if indeed such an order effect exists for these tasks, and these analyses will be used to inform study procedures in the future.

Publication Date


Subject Major(s)

Psychology, Biology

Current Academic Year


Faculty Advisor/Mentor

Dever Carney

Faculty Advisor/Mentor

Shannon Hahn


Virginia Commonwealth University. Undergraduate Research Opportunities Program

Is Part Of

VCU Undergraduate Research Posters


© The Author(s)

The Correlation of the Order Effect and Anxiety in Relation to the Carbon Dioxide Challenge and Screaming Lady Task