When considering whether or not to go out on a date with a guy, Samantha Tan, a sophomore at Indiana Wesleyan University, says she pays attention most to the eyes. “I feel like you can get a sense of their motives,” she says.
And so goes the age-old saying, “The eyes are the window to the soul,” but as a CalTech study on speed-dating has shown, Samantha isn’t the only one gleaning substantial information from a glance at a face. In fact, Dr. John O’Doherty, the lead researcher on the study, and his team discovered that after looking at a face for just four seconds we are able to determine how attracted we are to that person, and whether or not we will get along with them. “I think it is certainly intriguing that we can predict better than chance whether or not one would want to subsequently date someone based on a single photograph taken days before a social interaction,” says O’Doherty.
The study, which analyzed the snap judgments we make about people while speed-dating, took 39 heterosexual men and women, put them each in an functional MRI and scanned their brains while cycling through pictures of potential partners. The participants were asked to rate the pictures on a scale of 1 to 4, and asked the question, “How much would you like to date this person?”
They had four seconds to answer. In that four seconds, the scientists saw the brain light up in some fascinating ways.
Two Parts of the Brain
“We found that two distinct regions of the DMPFC [dorsomedial prefrontal cortex], the paracingulate cortex and the RMPFC [rostromedial prefrontal cortex], were significantly predictive of whether a romantic partner would be pursued or rejected,” write Jeffrey C. Cooper, Simon Dunn, Teresa Furey, and O’Doherty in their study published in The Journal of Neuroscience.
In other words, they discovered that two specific parts of the brain are engaged when we make split-second decisions about whether or not we will pursue a relationship with somebody. The first, the posterior part of the DMPFC, located along the middle of our brain in the frontal lobe, is still not very well understood. But O’Doherty says they’re starting to find that we use this part of our brain when trying to compare options. “We have shown previously that activity in this region is related to making comparisons between different available options in order to work out which option to select at the point of decision-making.”
Okay, so yes. This makes sense. When we see someone’s face and have to decide quickly if we’re going to ask them for a date or not, we are actively engaging that part of the brain which helps us strategize, pick and choose. “We certainly do know from other work I and others have done that the more posterior part of DMPFC is involved in other types of decision-making, such as when deciding whether to play a slot machine in a gambling scenario,” says O’Doherty.
But what made this study so novel was the second part of the brain which O’Doherty and his team watched activate while participants analyzed a photograph of their potential date’s face — the anterior part of the DMPFC, located just under our hairline at the front of our forehead. This part of the brain “is often implicated in processes related to the ability to ‘mentalize’ — that is, the capacity to think and make predictions about the intentions or beliefs of another person,” explains O’Doherty.
In other words, we use this part of the brain when we’re trying to imagine whether or not we’ll get along with this person, what they might say or do in response to us, and vice versa. “This mentalizing function is often very useful when interacting with other people socially as it allows us to make predictions about what other people are likely to do in a given situation, and also to think about the effects of our own actions on other people,” says O’Doherty.
Assessing Likeability
But how is it possible that we know whether or not we will “like” someone or get along with them, just by thin-slicing their face? Well, that is something O’Doherty does not yet know. “Exactly what information they are using in the photograph to enable them to make this judgment is unknown at this point — but clearly is an interesting topic for future research.”
Regardless of how we make the decision, the point is that we do, and that is predictive of who we will ask out and who we will decline. O’Doherty and his team were able to predict who the participants would date based on their scans of the brain taken less than two weeks before the speed-dating event.
“This study forms part of accumulating evidence to suggest that we are capable of making ‘thin-slice’ judgments about lots of things using very limited information,” says O’Doherty. “This seems to be particularly the case when it comes to decisions we need to make about other people — such as whether or not I should trust someone, or deem them competent or worthy of interacting with.”
Real Social Consequences
It’s important to note that these dates were not hypothetical. Within two weeks, the participants were sitting across from the actual flesh and blood versions of the pictures they had rated in the functional MRI.
And that was the driving thrust of this experiment. Ultimately, O’Doherty and his team were not just interested in how we make decisions about romantic relationships but rather how we make split-second decisions about actions with real social consequences.
“The overall goal of our work,” explains O’Doherty, “is not to understand what happens when people are engaged in dating behavior per se, although this is of course an interesting question in its own right, but more generally to understand what kind of information the brain deploys to make decisions and to understand how the decision gets made.”
In the end, what they are most interested in understanding is how psychiatric diseases and other disorders create impairments in the decision-making process. O’Doherty says that, “by working out how healthy brains make decisions, we ultimately hope to understand how the process goes wrong in various diseases.”
This article is updated from its initial publication in Brain World Magazine.
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