How the brain processes hierarchy

Whenever we start a new job, there is a period of time where we suss out the way things work, and perhaps more importantly who the key people are.  These social hierarchies become fundamental to our ability to do a good job, so a recent paper from DeepMind and University College London is of interest because it looks at the neurological mechanisms at play when we assess social hierarchies, and our place within them.

The analysis reveals that our brain defaults to create signals of social rank, even if it isn’t needed for the task we’re performing.  The authors believe that the finding has a range of possible values, not least in the generation of artificial intelligence.

The neurology of hierarchy

The researchers asked participants to perform a range of tasks whilst inside a fMRI scanner.  The task involved learning about the power structure of a made-up company that they were asked to imagine working for alongside a similar company that their friend worked for.

They learned about the hierarchy in the company by watching a number of ‘contests’ between employees that would see one or the other win.  They were then shown pictures of employees from each company, and were asked which company they worked for.

“We found that the way in which participants learn about the power of individuals was best explained by a process of Bayesian inference” the authors say. “Essentially you have an estimate about the level of power of each person, which you update as you receive new information (i.e., the outcome of a contest between 2 people.”

This allows us to develop knowledge of someones rank even if they’re not physically there.  For instance, if you see that employee A wins against employee B, who then goes on to win further contests against employees C, D and E, you can easily infer that employee A is high up the tree.

“We found that different processes seem to be used for learning about and representing a social structure that you yourself are part of, compared to a social structure that involves someone else” the authors continue. “The prefrontal cortex, a region that is highly developed in humans, was particularly important when participants were learning about the power of people in their own social group, as compared to that of another person. This points towards the special nature of representing information that relates to the self.” Indeed, sophisticated social interactions necessitate distinguishing one’s own thoughts, goals, and preferences from those of other people–a cognitive function we know humans in particular excel at.”

Why we love hierarchy

Of course, aside from the value this provides to AI researchers, it also reminds us of the way our brain naturally processes hierarchy.

This was replicated in a classic study conducted by researchers at Stanford University.  It found that if you put college freshman into a room and task them with solving a challenge, it tends to take less than fifteen minutes to create a hierarchy amongst the team.

The authors suggest that this is a natural part of being human, with children as young as five also quick to establish a hierarchy amongst their peers.  Sometimes this hierarchy is scarcely even visible.

Indeed, one study conducted by researchers at Kent State University looked at the speaking style of people when in groups.  They were studying the kind of very low frequencies that are barely visible to us, but underpin our speech.

They found that when in a group, our speech rapidly converges on the frequency level of the most dominant member of the group.  This switch typically occurs completely subconsciously, but it happens nonetheless.

So hierarchy is a natural part of being human, and now we have a greater understanding of how the brain processes that hierarchy.

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