Pet Forum / Mammals / Rats / August 2003

Of course, we already knew rats have complicated emotions, but this
morning I was reading some behavioral studies (articles are upstairs so
I'm going to paraphrase badly without the citation). The set-up for the
rats was this: They had to run a long straight course to a food reward.
The rats could see the reward in the distance. They would get the reward
whether they ran fast or ran slow, so their speed was dependent on their
degree of eagerness rather than fear of not getting the reward if they
were too slow.

Some of them were first habituated to a small reward, others were
habituated to a large reward. The speed with which they went to the
expected reward was the same in both groups. But when the rats habituated
to small rewards saw MORE food than they ordinarily would get, they ran
faster to get it, they were most eager. But the rats who expected big
rewards, if what they saw was the smaller reward, they practically walked,
the eagerness evaporated.

This was regarded as scientific evidence, rather than just pet-owner
projection of human characteristics, showing that rats that have developed
certain expectations will experience heightened delight if the expectation
is exceeded (hence running faster to the larger reward), but would
experience disappointment if the expectation were not met (hence no speed
to get the reward).

So our projecting emotions on to these guys is given the thumbs-up by science.

-paghat