Instinctive Influences

A 1961 article by Keller and Marian Breland suggested that instinct should
still be a part of psychology, despite its period of disgrace. In training performing
animals, the scientists witnessed a phenomenon they termed “instinctive
drift.” (It is interesting to note that although other terms, such as
“species-specific behavior,” were at that time preferred to “instinct,” the
Brelands stated their preference for the original label.) Instinctive drift refers
to the tendency of a creature’s trained behavior to move in the direction
of inherited predispositions.

The Brelands tried to teach pigs to place coins in a piggy bank; they
found that although the pigs could easily be taught to pick up coins and run
toward the bank, they could not be stopped from repeatedly dropping and
rooting at them. Raccoons could be taught to drop coins in a container but
could not be stopped from “dipping” the coins in and rubbing them together,
a drift toward the instinctive washing of food. Several other species
presented similar problems to their would-be trainers, all related to what the
Brelands willingly called instinct.

Preparedness is another example of an instinct/learning relationship.
Through conditioning, any creature can be taught to associate some previously
neutral stimuli with a behavior. Dogs in Ivan Pavlov’s laboratory at the
beginning of the twentieth century readily learned to salivate at the sound
of a bell, a signal that food would appear immediately. While some stimuli
can easily serve as signals for a particular species, others cannot. It seems
clear that animals are prepared by nature for some sorts of learning but not
others. Rats can readily be trained to press a lever (a bar in a Skinner box) to
obtain food, and pigeons can readily be trained to peck at something to do
so, but there are some behaviors that they simply cannot learn to serve that
purpose.

Conditioned taste aversion is yet another example of an instinctive influence
that has been well documented by modern psychology. In people and
other animals, nausea following the taste of food very consistently leads to
that taste becoming aversive. The taste/nausea combination is specific; electric
shock following a taste does not cause the taste to become aversive, nor
does a visual stimulus followed by nausea cause the sight to become aversive.
Researchers theorize that the ability to learn to detect and avoid tainted
food has survival value, so it has become instinctive. 447