Drive reduction theories are inadequate for explaining motivation for three reasons: A. They don’t explain why people sometimes aren’t motivated by internal needs. B. They don’t explain why people don’t stop being motivated when internal needs are satisfied. C. They don’t explain why people are often motivated by external incentives as well as internal needs.
Research has shown that the identical twins of homosexuals are much more likely to be homosexual than the fraternal twins of homosexuals. In turn, the fraternal twins of homosexuals are more likely to be homosexual than the adoptive siblings of homosexuals.
Maslow proposed that people are motivated by a hierarchy of needs and that people pay attention to higher-level needs only when lower-level needs are satisfied. The most basic needs are physiological needs and needs for safety and security. The next needs are for social interaction, followed by needs for esteem. The last needs are for self-actualization.
Critics of Kinsey’s research maintain that his sample was biased; that he used questionable methods, such as asking leading questions when interviewing subjects; and that he may have let his own beliefs influence his results.
Evolutionary theorists base their explanation on the difference in parental investment between males and females. Males invest less to produce offspring than do females. Males can increase their reproductive success by producing as many offspring as possible. Evolutionary theory predicts that men tend to choose partners who are attractive and youthful because these qualities imply good health and an ability to reproduce successfully. Females increase their reproductive success by being highly discriminating when choosing mates. They try to select males who have the most access to material resources, because such males can contribute the most to caring for offspring.