Chapter 2 Summary

Behaviors may be selected by evolution if they have survival value. Such behaviors are innate in the sense that they have no obvious original basis in learning.
Even innate behaviors can be modified with experience. In habituation, for example, responding that is elicited by a stimulus can decline if the stimulus is presented repeatedly. Habituation is a simple form of learning that occurs with many behaviors and stimuli, including behaviors elicited or controlled by food.
Evolution is a process that allows adaptation between generations; learning, on the other hand, is a process that allows adaptation within an animal’s lifetime.
Through instrumental conditioning, animals learn to increase their contact with good outcomes (Os with positive survival value) and decrease their contact with bad outcomes (Os with negative survival value). The law of effect describes this state of affairs. Behaviors increase if they produce good Os (reward learning) or prevent bad Os (avoidance or escape learning). They decrease if they produce bad Os (punishment) or prevent good Os (omission). The term reinforcement means strengthening; it is used to describe either reward learning (positive reinforcement) or avoidance and escape learning (negative reinforcement).
Shaping allows new behaviors to be added to an animal’s repertoire. In shaping, new behaviors emerge because successive approximations of the behavior are differentially reinforced. Shaping does not necessarily require a teacher, and it resembles natural selection in the sense that behavior is selected by its consequences.
In classical conditioning, animals learn to respond to signals for O. The response is adaptive because it helps the animal optimize its interaction with the upcoming O. Signals for food evoke responses that help the animal digest the meal and identify good and bad food sources. Signals for rivals and for mates evoke responses that prepare the animal for a fight or a sexual encounter. Danger signals evoke a constellation of physiological and behavioral responses that allow the animal to defend itself against the impending aversive O. Conditioning with drug Os allows the learning of adaptive responses, like the compensatory conditioned response, that help an animal maintain equilibrium.
Through classical conditioning, animals learn to approach signals for good Os as well as those that predict the absence of bad ones; they also withdraw from signals that predict the presence of bad Os or the absence of good Os. This tendency is called sign tracking, and it complements the law of effect in helping animals increase or decrease their contact with events that have either positive or negative survival value.
Extinction occurs in both instrumental and classical conditioning. It is a decline in responding that occurs when O no longer follows the signal or behavior that previously predicted it. Extinction allows the animal to continue to adapt as the environment changes. It is also useful in reducing unwanted behaviors in the clinic.
Classical and instrumental conditioning are both sensitive to the timing and the magnitude of O. Learning is best when O follows the signal or the behavior quickly and when O is large or intense.
Evolution may prepare animals to associate some events more readily than others. Such “preparedness” is evident in both classical and instrumental conditioning. This phenomenon was discovered in aversion learning experiments: Taste is a good signal for illness but a bad one for an electric shock, whereas audiovisual cues are bad signals for illness but good cues for shock.