Daniel Casasanto, newly appointed assistant professor in Psychology, is a leader in research on experiential relativity, the theory that people who speak different languages, come from different cultures, or have different kinds of bodies may think differently as a consequence.
“The goal is to figure out how experience shapes cognition, and how the diversity of human experience is reflected in our brains and minds,” he explained.
Casasanto didn’t start out as a relativity theorist. “I began studying relativity as a graduate student at MIT,” he said. “There, scholars like Noam Chomsky and Steven Pinker were arguing that linguistic relativity was wrong. Although languages may appear to differ from one another dramatically, these differences are superficial, and underneath the mind is universal.”
Casasanto designed studies to uphold this ‘universalist’ view of the mind, but his data didn’t cooperate. “The deeper I dug, the deeper I found linguistic relativity effects could go. The results didn’t support a universal mind – they showed that people who talk differently also think differently, in fundamental ways.”
Testing the impact of language on perception
Casasanto’s studies solved a decades-old problem in linguistic relativity research – how can you test for effects of language on thought without using language in the experiment? “If your task lets people put their thoughts into words, the relativity argument becomes circular,” said Casasanto. “We developed low-level perceptuo-motor tasks that overcame this circularity for the first time.”
Casasanto and his team found that visual stimuli that matched the participants’ linguistic metaphors changed their perception of pitch, but had no effect for participants who used a different metaphor.
Dutch participants, who use “high” and “low” to describe pitch, were affected by seeing lines placed at different heights. When the line was towards the top of the screen, they sang the pitch slightly sharp; when the line was towards the bottom of the screen, they sang the pitch slightly flat.
Farsi speakers, who talk about pitch in terms of “thin” and “thick”, were affected by the relative thickness of the lines. Thicker lines made them sing slightly more flat, and thinner lines made them sing slightly more sharp, but they were unaffected by lines of different heights.
The association between the metaphors and musical pitches held even when the participants were prevented from using words during the experiment.
How does language shape thought? “It’s not that language has some special connection to the rest of the mind. Rather, language mobilizes ordinary cognitive mechanisms – directing our attention, creating categories, or strengthening associations in memory,” said Casasanto. “Other forms of experience should be able to shape our thoughts in the same ways that language does.” To test this assertion, Casasanto proposed a new theory: bodily relativity.
Understanding how the body influences the mind
“Our bodies also mobilize attention, categorization, and memory,” Casasanto explained, “so people with different kinds of bodies, who interact with their environment in different ways, should form correspondingly different thoughts, feelings, and judgments.”
To find out whether people with different bodies think differently, Casasanto first probed the brains and minds of left- and right-handers. “Handedness, for our team, is like the fruitfly for geneticists – a small model system for testing big principles,” says Casasanto. This research has revealed some surprising differences between lefties and righties.
When asked which of two products they want to buy, which job applicant they would hire, or which of two alien creatures looks more trustworthy, right- and left-handers responded differently. Righties tended to choose the person, product, or creature they saw on the right of the page, but lefties preferred the one on the left.
“Idioms like ‘my right-hand man’ and ‘two left feet’ tell us that right is good and left is bad,” says Casasanto, “but lefties’ preferences show the opposite. This link between left-right space and goodness is forged by bodily experience.”
Beyond influencing emotional judgments, Casasanto believes that the way people use their hands may determine how emotions are organized in their brains. “A cornerstone of affective neuroscience is the finding that different emotions are produced by the left and right hemispheres, but nobody has understood why,” he said. “Using neuroimaging and electrical brain stimulation techniques, we’ve discovered that this hemispheric organization is tightly coupled to the way people perform emotionally motivated hand actions.”
Casasanto has shown that right- and left-handed politicians display their emotions differently through hand gestures. Righties gesture more often with their right hand when saying something positive and with their left hand when saying something negative, but lefties show the reverse tendency. “If you want to know what a politician is thinking, look at their hands,” says Casasanto, who plans to continue this research at UChicago. “Our psychology department has long been the nexus of gesture research, worldwide,” beginning with the work of David McNeill (professor emeritus in Psychology) and carried on by Susan Goldin Meadow (the Beardsley Ruml Distinguished Service Professor in Psychology).
Casasanto joins the University after serving on the faculty at The New School in New York. He received the 2013 Janet Taylor Spence Award for Transformational Early Career Contributions from the Association for Psychological Science. He is also the recipient of the James S. McDonnell Foundation’s Scholar Award, and a grant from the National Science Foundation’s Program in Perception, Action, and Cognition titled “How motor action shapes emotion in the brain.” Before earning his Ph.D. in Brain and Cognitive Sciences from MIT, Casasanto received a B.A. in English Literature from Oberlin College. He also earned diplomas in Vocal Performance from the Oberlin Conservatory and the Peabody Conservatory of Music, and worked as an opera singer in the US and Europe.