Examining Person Perception from a Neural Perspective

Assistant Professor of Psychology Susanne Quadflieg researches how we navigate our social world from a neural perspective.

As humans, we try to make sense of other people every day. Based on our own judgments and stereotypes deduced from social information, interactions, and expectations, we categorize them, classifying, say, the woman next door as a gossip, the man at work as easygoing, or the new friend as kind. While this processing may come as second nature, most likely don't think about why we respond the way we do or what factors influence that response. For NYU Abu Dhabi Assistant Professor of Psychology Susanne Quadflieg, understanding how we navigate our social world from a neural perspective is the focus of her current research. "I want to understand how the brain enables us to be a social species," she explained. "Everything you are stems from your brain. I find it the most fascinating thing!"

Quadflieg began working in the "relatively new field" of social neuroscience as an undergraduate at the University of Jena in Germany. Since then, she has conducted research in Europe, America, and, now, the Middle East. Often fueled by personal curiosity, Quadflieg has always been fascinated by the fact that humans are an ultra-social species. "We need other people, it's as simple as that," she explained. "At the same time, they can be our biggest danger. They may deceive or reject us, suffocate us with their expectations, or even harm us physically."

A New Twist to the Science of Social Interactions

In order to understand our perception of social interactions, Quadflieg is studying humans engaged in typical social activities, such as shaking hands, taking a walk, or engaging in conversation. Specifically, she seeks to determine the stage during the person perception process at which sensitivity to such interactions (and their inherent social meaning) arises.

Previous research has found that the brain has modules particularly dedicated toward perceiving human faces and bodies; however, this research typically considered these faces and bodies out of context. By looking at actual person interactions, Quadflieg has put human faces and bodies in context to study how our brain processes the same stimuli when they are presented within a social narrative. While undergoing functional magnetic resonance imaging (fMRI), a method that allows neuroscientists to measure neural activity, participants view images of two people presented on a uniform background. While some of these dyads show well-known social interactions, others consist of two people whose involvement with each other remains unclear to the perceiver. Through this control condition, Quadflieg can determine whether our brain perceives other humans differently depending on whether we can make sense of them.

As Quadflieg explained, "Compared to these control images, meaningful or easily understood social interactions elicit reduced activity in the brain's person perception modules. These results support the view that our social expectations shape the way our brains make sense of the visual input, not only at an inferential level but also at a perceptual processing stage. In other words, seeing people involved with each other in a way that you understand makes seeing them easier." Quadflieg has submitted her findings for publication and has planned follow-up projects on the topic. One such study will involve further probing to determine when in the processing stream the brain begins to distinguish between meaningful and non-meaningful dyads, as opposed to discovering where in the brain activity is taking place.

Neuroscientists have expended considerable effort in attempts to understand how the mind represents and organizes social knowledge.

Susanne Quadflieg, assistant professor of Psychology

Knowledge Representation and Knowledge Use

Her second project, which also uses the fMRI, investigates the nature of knowledge representation and knowledge use in the human brain. "Many people would find it rather simple to form an impression of a neighbor described as narrow-minded," Quadflieg said. "However, the question of how the human mind represents and integrates such social information is far from trivial." Besides providing the basis for retrieving the meaning of thousands of words, a person's repository of social knowledge holds the elementary units for many higher-order social-cognitive operations, including anthropomorphizing, mentalizing, and stereotyping. "Given these observations, it is unsurprising that neuroscientists have expended considerable effort in attempts to understand how the mind represents and organizes social knowledge," she said.

According to Quadflieg, researchers have begun to argue that the representation of social knowledge depends on a unique network of brain regions, with three specific regions — the medial prefrontal cortex, the temporoparietal junction, and the anterior temporal lobe — playing a particularly important role. Though all three regions have been found to be involved in a variety of social reasoning tasks, their exact functional contributions remain a matter of debate. Quadflieg expects that the three regions of the social brain are recruited differently depending on the type of social knowledge probed and the intended use of the knowledge. More specifically, "We predict that neural activity differs depending on whether social knowledge refers to the traits, states, or outer appearances of others," she said. "In addition, we expect that attributing social concepts toward a specific person — for example, is Tom kind? — causes the recruitment of additional neural resources compared to those used for mere semantic processing — such as, is the word kind related to the word nice?"

Snap Judgements

Quadflieg also plans to conduct research focusing on faces to answer questions such as why we judge some faces trustworthy and others not, and who we think is smiling out of genuine enjoyment and who is faking a smile. She will present photographs of human faces to her participants, who, among other methods of investigation, will be asked to numerically rate each face on a variety of dimensions. Quadflieg is currently building up the "face database" and will determine future studies based on its contents.

This research will be reflected in Snap Judgments, a course taught by Quadflieg that examines the mechanisms that explain this phenomenon. As she said, "I want to unravel a fundamental social mystery with my students: Why we often think we know things about others without ever having exchanged a single word with them?"

Based on discovering the neural foundations of perceptions or judgments formed by the collection of social information, interaction, and expectation, Quadflieg's research will address how the human brain makes sense of others. "I hope that this can help us in the long run to better understand why these skills are sometimes poorly developed — either because we have a momentary lapse (most of us have occasionally misinterpreted social situations), or because certain mental disorders such as autism or intense social anxiety make it particularly hard for some people to make sense of their social surroundings."

I want to unravel a fundamental social mystery with my students: Why do we often think we know things about others without ever having exchanged a single word with them?

Susanne Quadflieg, assistant professor of Psychology

Quadflieg has also set up a research laboratory, the Person Perception and Person Knowledge Lab, that targets questions of person perception and person knowledge with the help of various neuroscientific methods, including fMRI. As she said, "I'd like to make use of what makes this region so unique: so many different ethnicities and nationalities coming together, all bringing their own social rules and expectations. I want to understand these different realities."