There is no homunculus in our brain who guides us

There is no homunculus in our brain who guides us

M.R. O’Connor writes:

In the early 1980s, the psychologist Harry Heft put a 16 mm camera in the back of a sports car and made a movie. It consisted of a continuous shot of a residential neighborhood in Granville, Ohio, where Heft was a professor at Denison University. It didn’t have a plot or actors, but it did have a simple narrative: The car started moving at 5 miles per hour and made nine turns from one street to another and then came to a stop after traveling just under a mile. Heft then edited the film into two different movies. One showed just the vistas along the route, the expansive layout of environmental features, such as a group of houses or trees seen from a distance. The second film showed the transitions of the route, the parts between each vista where the view is occluded by, say, a turn in the road or the crest of a hill. He asked the study’s participants to watch either of the films and then brought them in person to the start of the route. Who would be able to find their way to the end? Were vistas or transitions more important to the process of what he called wayfinding, a form of navigation based on the perception of temporally structured visual information?

At the time, the dominant theory in psychology for how people find their way was the cognitive map, which posits that humans and many animals create representations of the environment in the brain that they use to navigate the world. These representations are thought to be “allocentric,” meaning they are independent of an individual’s “egocentric” point of view and show the spatial relationship of objects and landmarks to one other, allowing people to create novel shortcuts. Heft wasn’t sure what the results would be but he was sure that however the study’s participants found their way, they weren’t using cognitive maps. “I don’t think there is such a thing as a cognitive map,” Heft told me in 2017. “Cognitive maps are products of what we know of the layout of the environment. But they are not the basis of our knowledge.”

The cognitive-map theory has inspired decades of experiments and become a ubiquitous and widely used concept. Edward Tolman, a professor at the University of California, Berkeley, introduced the concept in a famous 1948 paper “Cognitive Maps of Rats and Men.” Three decades later, the neuroscientist John O’Keefe tried to put an electrode in the amygdala of a rat but inserted it instead into the hippocampus, the bilateral brain region deep in the temporal lobe, critical to memory formation. O’Keefe’s instrument began recording the firing pattern of a single cell that strangely seemed to correspond to the rat’s physical location in space. For O’Keefe, these “place” cells were evidence that the hippocampus was the site of Tolman’s cognitive map.

But the cognitive map has also been called the theory that refuses to die. The idea that there is an innate geometric representation of the environment in our brains has dissenters in brain science, anthropology, and psychology. As the neuroscientist Richard Morris points out in The Hippocampus Book, maps are things that people look at to extract information. “Adopting this term for the neural activity of a region of the brain seems to carry with it the mental baggage that there must be some cryptic homunculus that is ‘looking at’ the map to do likewise,” he wrote. There is no mechanistic explanation of how humans extract information from this map but because the map is such an easily understood concept, it lives on as a “beguiling metaphor.” [Continue reading…]

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