Animal brains, ours included, have evolved to be powerfully aware of where we are at any given moment. But it turns out that our brains are surprisingly, frustratingly two-dimensional, and that we're only dimly aware of changes in altitude.
That's the finding of new research from University College London. The team studied specific brain cells as rats moved through space: grid cells, which are used to measure distance, and place cells, which are used to understand location. When the rats moved upwards in altitude on little spiral staircases and climbing walls, the researchers found that the grid cells didn't respond at all, and the place cells only barely registered. This indicates that animal brains simply do not have the complexity to handle full three-dimensional awareness, and so we shortchange our knowledge of height in order to better navigate horizontally.
Lead author Kate Jeffrey explains:
"The implication is that our internal sense of space is actually rather flat — we are very sensitive to where we are in horizontal space but only vaguely aware of how high we are. This finding is surprising and it has implications for situations in which people have to move freely in all three dimensions — divers, pilots and astronauts for example. It also raises the question — if our map of space is flat, then how do we navigate through complex environments so effectively?
"It looks like the brain's knowledge of height in space is not as detailed as its information about horizontal distance, which is very specific. It's perhaps akin to knowing that you are "very high" versus "a little bit high" rather than knowing exact height."
If nothing else, this does rather make science fiction's most infamous lapse into two-dimensional thinking far more understandable.