51. The unsuspected power of stories, Part 3

In 2011, I wrote a book, still unpublished, about how stories work called The Scheherazade Code. This series of posts draws on that book. The last post discussed the way stories shape our sense of the world. This post describes why we are so susceptible to stories.

Stories are powerful because our brains are narrative engines. We are ‘hard-wired’ to make and respond to stories. According to neuroscientist Michael Gazzaniga, the left hemisphere of the brain houses what he calls ‘the Interpreter’. The Interpreter’s job is to make sense of all the impressions and stimuli we constantly receive, as well as of our actions, even where they are prompted by unconscious stimuli. The Interpreter weaves this together into a coherent narrative about why things are happening as they are. Our brain hungers for pattern and meaning. When there are gaps and facts that don’t fit, the Interpreter keeps the story seamless, even where necessary inventing memories of things that never happened.

Many brain areas are required for story-making. Studies of brain injury that affect people’s ability to construct or understand narrative have identified three distinct areas in addition to the brain’s language areas. Like the Interpreter, the language areas are in the left hemisphere. Narrative seems to involve the limbic system, particularly the amygdala and the hippocampus, (involved in emotion and memory). It also involves parts of the frontal lobes (involved in assigning meaning to events) and prefrontal lobes (involved in regulating impulses). People with damage to these different areas experience different impacts on narrative.

With modern scanning technology, it is possible to watch a brain listening to a story. Different brain regions light up when a new character enters the tale, when an action is performed, when a cause is described and so on. We use many of the same parts of the brain when we listen to a story as we would if we were performing the action ourselves. The brain areas that would be involved if we kick a ball are active when someone kicks a ball in the story.

We understand a tale by mentally simulating events of the story world. This is true whether we are reading a book or watching a movie. The narrative machinery, which must have evolved before we invented written language let alone motion pictures, seems to underlie any kind of story-telling. Whatever way it is presented to us, in an important sense we become the protagonists in the tale. Moreover, when we hear a story, our patterns of brain activity become aligned with and mirror those of other listeners and of the speaker. The simulation of the events of a narrative that we run in our brains is not simply a passive inner movie. We construct it actively and predict what we think is coming next.

The narrative machinery of our brain may be linked to our ability to recall memories. Most of us have little or no memory of events before we were around age two or three. This may be linked to the age at which children are able to organise their memories into a narrative. Research shows that the age of first memory seems to be related to how complex the conversations are between mother and infant. Interestingly, while the average age of earliest memory is around 3.5 years in Europeans, it is 2.7 years for Maoris, and 4.8 years in East Asians. Might this be to do with the observed fact that Maoris have a rich story-telling tradition? And also that East Asians discuss feelings about the past with their children less frequently than Europeans?

Why and when did humans evolve this capacity for making and telling stories? The most obvious reason is that it evolved along with language to allow people to share skills and information and to forge social bonds.
My own speculation is that the narrative brain was built on the machinery that predators use to hunt. A predator has to be able to recognise its prey and to navigate rapidly the space that separates it from the prey to make the kill. To do this, predators make mental maps of their environment. A predator can kill faster and more efficiently if it doesn’t have to process information about everything it sees. Instead, its brain creates a model of what it is looking for, and only when its eye sees something that matches the search image model are the hunting routines activated. Other things in the environment are ignored.

This emphasis on important things, and ignoring of unimportant things, is exactly what stories do. Exactly the same thing happens with expert observers. Trafton Drew, a psychologist at Harvard medical school, asked radiologists to inspect chest scans for signs of lung nodules, a possible sign of cancer. Unbeknownst to them, he had superimposed on some of the scans an image of a gorilla. Astonishingly, he found that 80% of these highly trained observers missed the gorilla. Radiologists’ search image is geared to cancer growths, not gorillas.

gorilla scan
The gorilla is in the upper right.

The brain region seems to be involved in both navigation and in narrative. This structure is the hippocampus. It is involved in making long-term memory and storing our mental maps. When the hippocampus is damaged, we have difficulty remembering where we’ve been or how to get where we’re going. London taxi drivers are required to master “The Knowledge”, a detailed grasp of the road layout of London, before they are licenced to drive the famous black cabs. And fascinatingly, they have a part of their hippocampus enlarged compared to the rest of us, perhaps as a result of all that studying of maps. The hippocampus and amygdala are involved in our ability to create and relate to stories. It is a fascinating speculation then that our story-making ability evolved from, and still shares features with, the much older machinery for making mental maps.

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