Skip to main content

Finding Common Ground: Susan Brennan and the Science of Collaborative Communication

Susan Brennan

You receive an email from a coworker. The email seems rude. Later while face to face your coworker she seems happy to see you. (Huh?) You ask an acquaintance to dinner. There is a long silence during which he avoids looking at your eyes. Then he responds with, “Ah, maybe.” (Dinner for one it is.) You’re telling a really complex story to a close friend. She nods, occasionally adding, “Wow!,” “Really?,” and the occasional “Oh.” She asks questions, makes eye contact, and smiles. (She is listening to you. You are on common ground. You are understood.)

These subtle communication cues — scrutinized by skilled actors and novelists, and, as it happens, scientists — are the flora and fauna of cognitive scientist and AAAS Fellow Susan Brennan’s multi-faceted world of research, a world that takes as its starting point the idea that when it comes to communication — as with the tango — it takes two. For Brennan communication is an act of collaboration.

“Most people’s naïve assumption about communication is that it’s about sending messages back and forth and just assuming that your message will be understood if you’re speaking the same language,” explained Brennan from her office at Stony Brook University in New York where she holds joint appointments in psychology, linguistics, and computer science.

“Communication, speaking and listening, is a tightly coordinated activity between two people,” said Brennan.

Over the decades, Brennan’s research has helped unveil the delicate dance that is communication — a dance choreographed in interjections and qualifying questions, in pregnant silences, in where we direct our eyes, and in the gestures and postures we assume.

Communication, according to Brennan, is about more than the messages we wish to convey. “It’s monitoring each other for how those messages are understood and taken up,” said Brennan.

Communication, of course, does not happen in a vacuum. (Here’s where Brennan’s work becomes especially interesting.) To communicate we need media.

Communication media are our phones, our computers, our social media accounts, and simply sitting down in a room and speaking face to face. The medium we use, Brennan’s research has shown, shapes our communication.

But before we get there, ask yourself this: If communication isn’t just sending messages back and forth, what is it? The answer, seen through Brennan’s work, is both profound and familiar. 

The human mind is now believed to be a kind of inference machine, constantly calculating the likelihood that something is true or false based on the available evidence.

Like a scientist trying to understand a highly complex system, we create and test conceptual models as part of our day-to-day existence, adjusting these models based on feedback from the environment.

When we communicate, we constantly seek evidence either confirming or disconfirming that we’ve been understood. As Brennan puts it: “Communication is about trying to share something about your mental state.”

Let that sink in. Communication is about sharing and comparing conceptual models

This process of two inner worlds meeting manifests as the familiar back and forth speakers and addressees engage in as part of everyday communication. It shows up as interjections (You didn’t!); qualifying questions (By “apple,” you mean the fruit, not the company, right?), as nonwords hovering around formal speech (those ums, uhs, huhs, and ahas that give spoken language its living texture); and as postures, gestures, facial expressions, and eye movements. As we receive new information based on these cues — this feedback — we make new inferences, adjusting our conceptual models.

“Speakers will revise what they are saying based on whether the evidence is or isn’t forthcoming from their addressees,” said Brennan. “At the same time, addressees are contributing to what speakers are saying both overtly — by completing their sentences sometimes — and covertly — with their looks, gestures, and other nonverbal cues.”

Brennan has spent most of her adult life steeped in various communication media. As an undergrad she studied cultural anthropology. She drew caricatures of politicos for her college newspaper, including of the soon-to-be impeached Richard Nixon. In her early 20s she worked as a techy in a news radio station, hanging mics and running cables. She went to the Massachusetts Institute of Technology where she studied at what is now the MIT Media Lab. There she made experimental films and — digitally transmuting her interest in the human face — created a computer program that could turn a typical face into a caricature.

By the 1980s, her passion for technology — she was then a self-described “technologist” and “hacker” — led Brennan to Silicon Valley where she worked for big name companies, including Apple, Atari, and Hewlett-Packard, doing highly experimental work and rubbing elbows with technological luminaries, including Don Norman and Alan Kay.

“I was surrounded by the technology of media without any theory or attention to the content,” said Brennan.

The needed theory came for Brennan, when, like many in Silicon Valley, she eventually took that short trip to Stanford University. There she met psycholinguist Herbert Clark, a long-time professor of psychology. Brennan received her PhD from Stanford and together with Clark developed the theory of grounding.

The idea of grounding is based on reaching or finding “common ground,” it’s the result that occurs after individuals have swapped enough information about their mental models to infer that they are talking about the same thing.

Almost from the get-go, Brennan, influenced by her already noteworthy career in tech, added her own unique caveat to the theory of grounding: grounding changes depending on the medium being used. This idea first appeared in a 1991 paper she co-wrote with Clark for the American Psychological Association, and it’s never really left. Her argument goes something like this:

Media of communication have affordances and costs that together affect all those subtle communication cues that let us know that we are talking about the same thing. 

An affordance is simply what a medium affords you the ability to do. A cost — at least for the purposes of this discussion — is what a medium keeps you from doing. Media — and by extension their affordances and costs — aren’t good or bad per se. Rather media can be better or worse tools depending on the task you wish to accomplish.

For instance, a phone call affords you the ability to hear the nuances of your friend’s voice, but these nuances take time to process when compared to something like a text. So, if you want to send a simple message quickly (Beers tonight?) a text, not a phone call, is the better medium. Talking on the phone instead of texting, costs you time.

Conversely, if your message is complex (expressing the similarities and difference in the collected works of David Foster Wallace and Haruki Murakami) and time is not a factor, the phone is the better medium.  

Over the years Brennan has refined her field’s understanding of the relationship between grounding, media, and tasks. In the processes, her work has revealed volumes about what it means to communicate in the digital age. This includes a 1999 paper on emails with the telling title, “Why do Electronic Conversations Seem Less Polite?” (The answer, in a nutshell: emails provided fewer affordances for sharing and testing conceptual models.)

However, as interesting as this work is, Brennan’s biggest strength in dissecting the relationship between grounding and media has been to use communication media — their affordances and costs — as research tools.

Consider her 2007 study examining eye movement published in the journal Cognition.

Two individuals are given a task. They need to find the same place on a map. They are being timed. In separate rooms from one another, they sit in front of two identical computer monitors. There are microphones and speakers. Mounted on their heads are devices that track their eye movements.

Similar to a mouse arrow on a computer desktop display, the eye tracker’s cursor shows up on the map, effectively affording the two partners the ability to know exactly what each other is looking at. Brennan and her colleagues then manipulate these affordances experimentally. Some pairs get both affordances. Other pairs just see eye movements but can’t speak to one another. The results:

Surprisingly pairs that could both see each other’s eye movements and speak to one another performed the search task slower than subjects that could only see one another’s eye movements. Being able to talk produced a real cost — as measured in time — to their collaboration.

So, what does all this mean?

For starters, we should be mindful of our media, according to Brennan. The one time technological enthusiast is leery of social media formats, such as Twitter, because they have lots of affordances (it takes very little to send a message) and few costs (messages are very rarely edited or thought about especially hard before being sent).

“What Twitter does is takes away the entire cost of broadcasting. And if you’re impulsive to begin with, it is the most impulsive kind of media,” said Brennan.

But there is also a truly uplifting message about humanity in Brennan’s work as well: the power of collaboration.

In the real world we very rarely meet other people with the same conceptual models, the same knowledge base, or the same experiences as ourselves. And yet, often enough, we make it work. We make ourselves understood. “The fortunate thing is, in language use, people are very flexible. So, even if one communication partner is much more capable than the other, the two of them can distribute their effort so they get the job done. Most of my work is steeped in that idea.”

In other words, it takes two.