Biological Factors in Learning
STEP 4 Review the Knowledge You Need to Score High
Mirror neurons in the premotor cortex and other portions of the temporal and parietal lobes provide a biological basis for observational learning. The neurons are activated not only when you perform an action but also when you observe someone else perform a similar action. These neurons transform the sight of someone else’s action into the motor program you would use to do the same thing and to experience similar sensations or emotions, the basis for empathy.
Taste aversions are an interesting biological application of classical conditioning. A few hours after your friend ate brussels sprouts for the first time, she vomited. Although a stomach virus (UCS) caused the vomiting (UCR), your friend refuses to eat brussels sprouts again. She developed a conditioned taste aversion, an intense dislike and avoidance of a food because of its association with an unpleasant or painful stimulus through backward conditioning. According to some psychologists, conditioned taste aversions are probably adaptive responses of organisms to foods that could sicken or kill them. Evolutionarily successful organisms are biologically predisposed or biologically prepared to associate illness with bitter and sour foods. Preparedness means that through evolution, animals are biologically predisposed to easily learn behaviors related to their survival as a species, and that behaviors contrary to an animal’s natural tendencies are learned slowly or not at all. People are more likely to learn to fear snakes or spiders than flowers or happy faces. John Garcia and colleagues experimented with rats exposed to radiation and others exposed to poisons. They found that rats developed conditioned taste aversions even when they did not become nauseated until hours after being exposed to a taste, which is sometimes referred to as the Garcia effect. Similarly, cancer patients undergoing chemotherapy develop a loss of appetite. They also found that there are biological constraints on the ease with which particular stimuli can be associated with particular responses. Rats have a tendency to associate nausea and dizziness with tastes but not with sights and sounds. Rats also tend to associate pain with sights and sounds but not with tastes.
Sometimes, operantly conditioned animals failed to behave as expected. Wild rats already conditioned in Skinner boxes sometimes reverted to scratching and biting the lever. In different experiments, Keller and Marian Breland found that stimuli that represented food were treated as actual food by chickens and raccoons. The Brelands attributed this to the strong evolutionary history of the animals that overrode conditioning. They called this instinctive drift—a conditioned response that drifts back toward the natural (instinctive) behavior of the organism. Wild animal trainers must stay vigilant even after training their animals because the animals may revert to dangerous behaviors.