Weekly Features


IU undergrads design palm sweat sensors to test results of psychological experiments

Mike Pipher, IU Communications

Jan. 30, 2014

IU freshman Bradi Heaberlin had the chance to seriously get into her boyfriend’s head -- and earn course credit for her efforts.

In Ben Motz’s “P155: Intro to Psychological & Brain Sciences” honors tutorial, each student built a palm sweat sensor device that measured reactions to outside stimuli. The measurement of this sweat, known as skin conductance, helps indicate psychological states such as arousal and stress.

For her experiment, Heaberlin collected 10 film clips meant to evoke such feelings as disgust, fear, happiness, sadness and neutrality. She tested 14 people but chose to discard the data of four who experienced some interruption or technical difficulty. The remaining 10 were divided into groups of five who were asked to suppress their emotions and five non-suppression group participants.

Inside IU recorded her showing the clips to her boyfriend, Reid Ralston.

“Some film clips I showed him included a scene from the film ‘Pink Flamingos,’ in which a woman eats dog feces -- obviously meant to evoke disgust -- the scene from ‘The Shining’ showing the twins at the end of the hallway, meant to evoke fear, and a scene from the film ‘The Champ’ in which the young boy's father dies, to evoke sadness,” Heaberlin said.

Ralston’s responses were similar to those of Heaberlin’s other participants. While she expected conductance to rise for all participants -- and more for those suppressing their emotions -- she was surprised that skin conductance actually decreased at the beginning of every film clip for every single participant. 

“My hypothesis was that skin conductance would be higher for those in the ‘suppression’ group -- which turned out to be accurate -- but I thought the measurements would be a matter of whose skin conductance increased the most, not decreased.”

Motz, a senior lecturer and director of pedagogy in IU’s Department of Psychological and Brain Sciences within the College of Arts and Sciences, said the honors students in the weekly, supplemental discussion section of the class came from majors including education, journalism, business, exercise science, microbiology, psychology and political science.

He describes the reasoning behind the project through the example of a mood ring.

“Let’s say I hand you a mood ring and just ask you to play with it,” Motz said. “It wouldn’t take long before you’d start asking questions like: ‘What would I need to do to change the color of this ring?’ Or, ‘I wonder what my best friend’s color will be?’ I wanted to harness that playfulness in a learning context. I wanted to give students an opportunity to explore mental states by measuring something objective and physiological.”

Unfortunately, he said, mood rings don’t actually work -- and most research tools for measuring mental states, such as an fMRI and EEG, are expensive and inaccessible without intensive training. The skin conductivity measurement devices provided a bridge between the playful accessibility of mood rings and the scientific rigor of physiological data acquisition devices. 

“Students explored some really cool topics,” Motz said. Among them: Whether winning something for yourself or winning the same thing for a friend would result in more arousal (friend-benefitting was much higher); whether the emotion conveyed in music would cause corresponding changes in the listener (in certain situations it did; others it didn’t); whether the effect of meditation on skin conductance could be modulated by the experimenter commenting on whether meditation “works” before the experiment (yep). 

Creating the contraptions -- a process that involved wire-stripping, crimping and soldering -- was a challenge for even the technology-savvy in the class. The build took twice as long as Motz had anticipated. “There was a fried microprocessor, some loose and flickering TFT displays, and a couple that never quite worked right -- I loaned mine out so that students could still do their research.” 

He said the whole project might have “crashed and burned” if not for the generosity of the Department of Psychological and Brain Sciences’ Electronics Shop engineers, Tony Walker and Jeff Sturgeon. 

Walker and Sturgeon met individually with students and helped to troubleshoot technology issues. 

“Tony and Jeff were outstanding examples of the tremendous research staff and infrastructure at Indiana University, and I’m deeply indebted to them for loaning some of their time to undergraduate education,” he said. 

And while the construction portion of the class was challenging, it presented students with an opportunity for them to learn about something that might otherwise have been inaccessible.

“In the end, the students had crafted a device that facilitated playful exploration of the curricular material and helped students think scientifically about the measurement of mental states,” Motz said.

Heaberlin said the experience showed her how to ask questions in a way that makes them testable. She found the building of the machine to measure skin conductance helpful, too.

“I think sometimes we use those pieces of technology without understanding or appreciating what goes into making them," she said. "By building and using our own machines in experiments we were able to design and execute, we were able to look at and be involved with psychological research from new and interesting perspectives.”

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