For instance, social psychologists have found that we are attracted to others who are similar to us in terms of attitudes and interests (Byrne, 1969), that we develop our own beliefs and attitudes by comparing our opinions to those of others (Festinger, 1954), and that we frequently change our beliefs and behaviors to be similar to those of the people we care about—a process known as conformity.

experience. For instance, when a boy turns to a girl on a date and says, “You are so beautiful,” a behaviorist would probably see that as a reinforcing (positive) stimulus. And yet the girl might not be so easily fooled. She might try to understand why the boy is making this particular statement at this particular time and wonder if he might be attempting to influence her through the comment.

The idea that our memory is influenced by what we already know was also a major idea behind the cognitive-developmental stage model of Swiss psychologist Jean Piaget (1896–1980).

These actions correspond well to the processes that computers perform.

For example, it has been argued that the emotion of jealousy has survived over time in men because men who experience jealousy are more fit than men who do not. According to this idea, the experience of jealously leads men to be more likely to protect their mates and guard against rivals, which increases their reproductive success (Buss, 2000).

Fitness refers to the extent to which having a given characteristic helps the individual organism survive and reproduce at a higher rate than do other members of the species who do not have the characteristic.

one’s thinking was relevant only to one’s behavior

Thus the structuralists were the first to realize the importance of unconscious processes—that many important aspects of human psychology occur outside our conscious awareness, and that psychologists cannot expect research participants to be able to accurately report on all of their experiences.

An important aspect of the structuralist approach was that it was rigorous and scientific. The research marked the beginning of psychology as a science, because it demonstrated that mental events could be quantified.

Titchener was a student of Wundt who came to the United States in the late 1800s and founded a laboratory at Cornell University. In his research using introspection, Titchener and his students claimed to have identified more than 40,000 sensations, including those relating to vision, hearing, and taste.

These studies marked the first time researchers realized that there is a difference between the sensation of a stimulus and the perception of that stimulus, and the idea of using reaction times to study mental events has now become a mainstay of cognitive psychology.

For instance, our judgment may be affected by our desires to gain material wealth and to see ourselves positively and by emotional responses to the events that happen to us.

There has also been an increasing influx of women into the field. Although most early psychologists were men, now most psychologists, including the presidents of the most important psychological organizations, are women.

The approaches that psychologists have used to assess the issues that interest them have changed dramatically over the history of psychology.