A new study led by scholars at the School of Psychological Science at Oregon State University finds a significant lack of diversity among participants in psychophysiology studies. Psychophysiology is the study of the intersection between psychological and physiological processes, such as the increase in heart rate or brain activity people experience when feeling heightened emotions.
In reviewing existing scientific literature, the study found that in less than half of the relatively small segment of psychophysiology studies that even included demographic data on race, no more than 14 percent of participants identified as Black, and even fewer identified as Hispanic, Asian, Indigenous, or another race. The authors note that the true percentage of Black participants is likely even smaller than they found, as the studies reporting demographic data likely had a greater proportion of nonwhite participants than the studies that didn’t release any demographic data at all.
Many methods for collecting physiological data use electrodes placed directly on the skin: EEGs (electroencephalogram) measure electrical activity in the brain and require contact with the scalp; electrodermal activity (EDA) sensors measure changes in conductivity produced in the skin by monitoring sweat glands. But these technologies were developed to work best with physical attributes most commonly associated with White people, like light-colored skin and thin straight hair, researchers say. EEGs are not as effective on people with thick, tightly coiled hair types, and EDA is not as responsive on Black skin.
Because of the instruments’ difficulty measuring physiological effects, Black participants are more likely than White participants to have their results discarded from scientific studies, the authors wrote. They also noted that when EEG and EDA data from nonwhite participants is included, the technical limitations in equipment may result in skewed interpretations of those participants’ physical reactions and perpetuate myths about biological differences between racial groups
The full study, “Whose Signals Are Being Amplified? Toward a More Equitable Clinical Psychophysiology,” was published on the website of the journal Clinical Psychological Science. It may be accessed here.