So, back in my days as a wee lad studying Behavioral and Cognitive Neuroscience, I did a series of studies looking at age and navigation strategy. You can find the full article here.
Sadly, that article lives behind a pay wall, so I'll put a short summary here.
I was interested in how older adults got lost more often than younger adults. There was a good amount of research showing that areas that were thought to be associated with navigation either atrophied or became progressively less connected to other parts of the brain as age advanced. Just as importantly older adults were reporting that they had less confidence in navigating through their environment than did younger adults.
I thought it was possible that older adults were using a different navigation strategy than younger adults. The two primary methods for navigation are:
- Egocentric (reference): individual remembers directions or a route based on a frame of reference centered on the individual movement, independent of absolute position.
- Allocentric (place): individual remembers directions or a route based on a frame of reference external to the individual, based for example on using a cognitive map with external reference points.
There are well known methods for testing each of these. The Morris Water Maze is a good measure of allocentric navigation
Likewise the T-Maze was a good measure of egocentric navigation and allocentric navigation.
Older rats showed deficits in studies of the Morris Water Task but not the Egocentric Version of the T-maze and older rats took longer to complete trials of the Morris Water Task
But did this apply to humans? To find out, I created versions of the Morris Water Task and a Y-Maze (modified version of the T-maze) in Unreal Tournament 2003 so that humans would have the privilege of doing tests like rats.
In this case, the Y-maze became a measure of strategy preference.
We did this by placing older and younger adults in a virtual environment where they could first learn to complete a task using either an allocentric or egocentric strategy, and then switching their start location. If they went to the same location in space, regardless of route, we inferred they were using an allocentric strategy. If they followed the same route, regardless of location in space, we inferred they were using an egocentric strategy. We repeated this test multiple times in order to be sure that preferences were real and not due to random chance.
So we found some really interesting results:
While younger adults had no statistically significant bias in preference, older adults a a strong bias towards an egocentric strategy.
Cool result, but did it generalize to their performance in a classical measure of navigation?
We tested all the same individuals in the Morris Water Maze, and measured their time to finding their way out of the pool, total distance traveled and, during the probe trials when there was no way out of the pool, how many times they crossed the area where the platform would have been.
The most interesting finding was that there was an interaction between age and strategy preference on average time to completion of the water maze, a measure of how well the participants were learning the location of the hidden platform.
In effect, individuals of either age that had an egocentric preference on the Y-maze performed somewhat poorly on the Allocentric focused Morris Water Task. However, while younger adults that preferred an allocentric strategy did better on the Morris water task, older adults who did so performed worse than all other groups.
This was a surprising finding. I'd expected to find older adults that used an allocentric strategy to have better preserved navigation systems. Instead, it seems some older adults persisted in using a strategy that their brains could no longer support, resulting in poorer navigation performance.
For stats and a full discussion of these findings, check the original scientific article. I had a lot of fun with this work, and I sometimes miss interacting with old people as they try to use a joystick to play video games for science.