Disgust – it’s an emotion we experience when we encounter things that are
dirty, impure, or otherwise contaminated. From an evolutionary standpoint,
experiencing the intense, visceral sense of revulsion that comes with disgust
presumably helps us to avoid contaminants that can make us sick or even kill
us. But new research suggests that disgust not only helps us to avoid
impurities, it may also make us better able to see them.
If something looks dirty and disgusting, we typically assume it’s
contaminated in some way; when something is white, however, we are more likely
to assume that it’s clean and pure. Research has shown that people from many
different cultures hold this association between lightness and purity, which
may explain why we prefer white teeth, white operating rooms, and white
porcelain bathroom fixtures.
“In the psychology of purity, even the slightest deviation from a pure state
(i.e., whiteness) is an unacceptable blemish,” observe psychological scientist
Gary Sherman and his co-authors.
They hypothesized that if feeling disgust motivates people to create or
protect pure environments, it may also lead them to prioritize the light end of
the visual spectrum. For people trying to preserve cleanliness and purity, the
ability to distinguish even slight deviations from a light shade like white may
become particularly important.
Sherman, who is now at Harvard
School of Government, and his co-authors investigated this hypothesis in three
studies, in which they tested participants’ ability to make subtle gray-scale
discriminations in both ends of the light spectrum. Their findings are
published in Psychological Science, a journal of the Association for
In their first study, 123 college students were presented with sets of
rectangles. In each set of four rectangles, one rectangle was either slightly
darker or slightly lighter than the others. The participants were asked to
indicate which of the four rectangles in each set was different from the other
three. After completing the discrimination task, they completed a survey that
measured their overall sensitivity to disgust.
In general, the students were better at identifying the rectangle that stood
out when the rectangles were presented on the dark end of the visual spectrum.
But the researchers observed a significant relationship between participants’
performance on the light end of the spectrum and their levels of trait disgust
– people who showed higher sensitivity to disgust also showed better
performance on the light end of the spectrum relative to the dark end.
Importantly, this effect was specific to disgust, as there was no such
relationship between participants’ levels of trait fear and their
These findings were confirmed in a second study, showing that students who
reported greater disgust sensitivity were better at distinguishing a faint
number set against a background of a nearly identical shade presented on the
light end of the visual spectrum relative to the dark end.
Based on these findings, Sherman
and his co-authors wondered whether disgust might actively influence what
people perceive. Based on the idea of perceptual tuning, they hypothesized that
inducing disgust would actually “tune” participants’ visual perception,
enhancing their ability to discriminate among small deviations in lightness.
In the third study, participants were presented with a slide show of
emotional images designed to elicit either disgust (i.e., images of
cockroaches, trash) or fear (i.e., images of a handgun, an angry face). They
then completed another perceptual discrimination task.
Just as in the first two studies, greater trait disgust predicted better
performance on light-end trials relative to performance on dark-end trials. But
the emotional images had different effects depending on the participants’
disgust sensitivity. For participants who were low on trait disgust, viewing
disgusting images seemed to have no effect on their discrimination performance
on either end of the spectrum. For participants who were highly sensitive to
disgust, however, viewing disgusting images significantly enhanced their
performance on light-end trials.
“Research on the experience-altering nature of emotion has typically focused
on nonperceptual experience, such as changes in cognitive appraisals. It is
clear, however, that these influences extend to perception,” the researchers
Together, the three studies provide evidence for an interactive relationship
between disgust sensitivity and perceptual sensitivity that may ultimately help
us detect and avoid the germs, toxins, and other contaminants around us.
This research was co-authored by Gerald Clore of the University of Virginia
and Jonathan Haidt, who is now at the New York University Stern School of
For more information about this study, please contact: Gary D. Sherman at firstname.lastname@example.org.
The APS journal Psychological Science is the
highest ranked empirical journal in psychology. For a copy of the article
"The Faintest Speck of Dirt: Disgust Enhances the Detection of
Impurity" and access to other Psychological Science research
findings, please contact Anna Mikulak at 202-293-9300 or email@example.com.
For Immediate Release
Association for Psychological Science