Thursday, February 03, 2011
Are you as smart as a rat? A rat can learn a lot of things with just the first attempt. For example, in the old days, exterminators used to use poisons such as strychnine. What they discovered was that some rats who ate the bait were never killed. If they survived the seizures of the first exposure, they learned not to eat that particular bait again. It’s called “bait shyness.” As a result, exterminators now use a different poison, Warfarin, that does not kill right away. The rat slowly bleeds to death over many days and does not realize any connection between eating that bait and getting sick. The explanation for the difference is illustrated in Figure 1.
Figure 1. One-try learning by rats being fed poison. In the top example, using strychnine, the rat gets sick soon after eating the bait. If it survives, it remembers an association between eating that particular kind of food and getting very sick, and it won’t eat the poison ever again. If, however, it takes a while to become sick, as with the anti-coagulant Warfarin, the rat is unable to make a connection between being sick and eating the bait. So, it keeps eating the bait every time it gets hungry.
Similar one-try learning has been demonstrated in two common types of experiments. In one type, the test apparatus is a large box, the floor of which is an electrified grid. In the middle of the floor, there is a safe-island platform that is not electrified. When an untrained rat is placed on this platform, it immediately runs to the walls, because rats feel vulnerable out in open spaces. But of course, the rat gets a learning experience of having its feet shocked. If you take the rat out, put it back in the home cage and re-test it the next day, the rat stays on the safe platform. Despite its natural inclination, it stays on the platform because it learned —in just one try —not to step off that platform.
Another example is a water maze. Put a rat or mouse in a tub of water and it swims desperately about hoping to find some escape. If there is a platform at one end it can climb up on, the rat, once it sees it, swims immediately to the platform and climbs up on it. If there is some kind of indicator of where the platform is, such as a light above it, and you fill the tub with a milky liquid where the platform cannot be seen, an untrained rat swims around until it accidentally finds the platform. Take the rat out, put it in the home cage, and re-test the next day, and the rat swims immediately to where the light and the safe platform is. Learning has occurred in just one try.
In all such learning situations there is one huge caveat. That deals with what happens immediately after the one-try learning. If some new learning situation occurs at that time, the learning will be disrupted and not formed into a lasting memory. For example, the memory will not form if in the foot shock or swim maze case immediately after the learning the investigator puts the rat in another learning situation or even just some distracting situation, such as putting the rat into a cage with strange rats rather than returning it to the home cage. Re-testing the next day will indicate that the rat never learned. Actually, it just forgot, because new stimuli immediately after learning interfere with forming a lasting memory.
This is the most common explanation of failure for humans to remember new learned events. After all learning events, a certain amount of uninterrupted time is needed to “consolidate” the short-term memory into a more lasting one.
Now consider how the rats might learn these things in one try. They have no language. The must surely rely on what they see. That is they must be making an association with something they see out in space: a certain kind of food that made them sick, a grid of bars that shocked their feet, a light cue showing where a safe platform was located. So, objects and where they are in space are powerful memory aids.
Memory gimmicks often use some kind of mapping technique, such as associating what you want to remember with location of objects in a room. I have discussed these in my book, Thank You Brain for All You Remember. Now I have a new and better image-mapping technique for one-try learning. I include it free in a revision of my e-book for students, Better Grades, Less Effort. The technique can be applied to most anything, is easy to use, and the maps are adjustable for any number of objects or ideas to be remembered. Moreover, sequential ordering is built-in. You can get the ebook for only $2.49 in all formats from Smashwords.com (http://www.smashwords.com/books/view/24623).