Researchers at the University of Chicago are investigating fundamental questions about how humans acquire and respond to language. Students in the College are contributing to these efforts, employing technologies such as attention-tracking software and AI-powered semantic analysis.
One area of focus is understanding how infants learn language in different cultural contexts. Tessa Bracken, a second-year linguistics major, works as a research assistant in ChatterLab under Professor Marisa Casillas. Bracken spends time annotating videos of babies listening to various types of speech, using specialized software to monitor where infants direct their gaze and how long they remain attentive.
The lab is exploring whether infants across cultures—from Chicago to Papua New Guinea—prefer certain ways adults speak to them. The team examines infant-directed speech, which is characterized by exaggerated intonation and slower tempo, alongside adult-directed and other-infant speech.
Bracken explained: “No one really knows exactly how infants acquire language. I was fascinated by this process that’s such a mystery.”
She noted that some theories suggest infants favor infant-directed speech because it is easier for them to replicate. However, cross-cultural data collected by the lab indicates that this explanation does not fully account for observed preferences.
“If replicability is what makes IDS preferable for infants, then infants would prefer other infant speech over infant-directed speech,” said Bracken. “The data was not consistent cross-culturally. That was convincing evidence that replicability wasn’t the full story.”
Bracken added: “In America, we believe we’re attuned to how to raise a genius. But all these factors we consider crucial probably don’t impact language acquisition quite as much as we assume.”
Her work also involved comparing linguistic environments in Chicago with those in indigenous communities in Bolivia, Mexico, and Papua New Guinea. In some places like Rossel Island in Papua New Guinea, children primarily hear ambient adult conversation but still acquire language at similar rates as children elsewhere.
Bracken's interest extends beyond empirical research; her study of classical languages has informed her perspective on how different grammatical structures shape thought across cultures.
“The same idea is expressed so eloquently in Latin but doesn’t translate well to English, and that difference has always been really interesting to me,” she said. “There’s almost always a gap between the thoughts that we have in our head and how we express them to the outside world.”
Another student researcher, Surya Chinnappa—a fourth-year linguistics major—takes an experimental approach at APEX Lab led by cognitive psychologist Howard C. Nusbaum. Chinnappa studies what makes religious sermons compelling by analyzing audience responses to Catholic homilies and coding them for semantic patterns.
“It’s a really interesting intersection, taking subjects that have historically been studied very productively by humanistic disciplines and introducing them to scientific study,” said Chinnappa.
Participants rate sermons on compellingness while Chinnappa codes responses based on emerging semantic dimensions. This research may extend beyond religious contexts into political or marketing communications through collaboration with Father Edward Foley and the Catholic Theological Union.
“We are synthesizing psychological expertise and my own linguistic experience with the domain expertise of people who have trained in the theological practice of crafting these homilies,” he said.
Chinnappa aims eventually to integrate his manual coding system into an AI agent capable of predicting sermon impact based on thematic content while maintaining transparency about its methods.
“We want every step of the way to be intelligible and interpretable to human researchers so that we can continue to be in conversation with collaborators working on different aspects of the project,” said Chinnappa.
Both Bracken and Chinnappa emphasize challenging assumptions within their fields while applying advanced technologies without losing sight of human insight into language processes.
“You’re not just contributing to your professor’s project, you’re contributing to a long line of research on the larger topic of language,” said Bracken.
Chinnappa reflected: “The past few years, with advancements in computational complexity and artificial intelligence, have definitely shaken up the world in terms of how we think about language.”
A version of this story appears on the University of Chicago College website.