@PLOSNeuro #SfN14 highlights: Leonhard Schilbach on the “dark matter” of social neuroscience

Do we think about others differently when we interact with them, rather than just watching?

Leonhard Schilbach, a psychiatrist and social neuroscientist at the University of Cologne, thinks as much, and has made a career out of understanding what he terms the “dark matter” of social neuroscience: social interaction.

In his talk in the “Toward Naturalistic Interactive Neuroimaging” symposium at this year’s SfN, Schilbach explained why social interaction has remained relatively unstudied compared to other forms of social cognition—in short, because it’s not accounted for by popular theories that explain how we make sense of other minds.

Traditionally, social neuroscience has been dominated by two approaches: what Schilbach termed the “first-person” approach, which accounts for our understanding of other minds through a projection of our understanding of ourselves, and the “third-person” approach, which assumes that we make use of a developed theory of other minds.

Schilbach claims that both theories “assume an epistemic gap between self and other” — and as a result, may not fully account for the reality of social cognition during interpersonal interaction. To overcome this, he argues that we need a “second-person” approach to social cognition: one that accounts for the possibility that social cognition in interactions is different from that involved in observation alone.

The case of joint attention

The Schilbach lab investigates social cognition in interactions using a novel experimental paradigm: subjects use their eye movements to interact with an on-screen virtual avatar while lying in the MRI scanner, allowing a simulation of social interactions without the technical challenges of jamming two people into one scanner.

They’ve used this paradigm to investigate the phenomenon of joint attention: as Schilbach put it, to “look at something together with someone, and know that we both are looking.”

Joint attention can be either initiated (when you look first at the object, then at the other person), or followed (when you look at the other person first). While this may not initially seem like a paradigm with particular clinical relevance, he pointed out that children with autism don’t “initiate shared experience”, suggesting an underlying abnormality in this process.

In an fMRI study, Schilbach and colleagues told subjects that a virtual character they saw on-screen represented a second person outside of the scanner, who would interact with the subject continually over the course of the experiment. The avatar would then either ignore the subject’s reciprocal gaze, or be guided by it in joint viewing, allowing the researchers to examine whether the neural correlates of joint attention are different when the shared experience has been initiated, rather than followed.

The researchers found a greater response in the ventral striatum, an area involved in reward and motivation, in the self-initiated condition—suggesting that the initiation of joint attention, and perhaps other forms of social interaction, may be its own reward.

In support of this hypothesis, subjects reported more enjoyment during the behavioral task if the avatar had shared their visual attention rather than antagonizing it.

Second-person neuropsychiatry

Schilbach argued that in psychiatric disorders, deficits more commonly lie in social interaction than in social observation, making a “second-person” approach all the more critical. In support of this claim, he offered the example of cocaine dependence: cocaine users rate joint attention as less-pleasant compared to people who don’t use cocaine. They also have blunted activation in medial orbito-frontal cortex, another region implicated in reward, during the social condition of the task.

Furthermore, the degree of blunted activation in the OFC is correlated with social effects of drug abuse: cocaine users with more blunted OFC activation tended to have smaller social networks than those with a more normal pattern of activation.

Together, these findings suggest that shedding light on social neuroscience’s “dark matter” may have implications beyond the lab. More research into social interaction could lead to a better understanding of — and possibly better treatment for — the many psychiatric disorders involving deficits in social cognition.