Psychology2016

412 CHAPTER 10

a set of genes, donated on the mother’s X chromosome, that might be responsible for their

sexual orientation. These findings have been supported in other research as well (Hu et al.,

1994; Sanders et al., 2015; Turner, 1995).

One of the most common behavioral findings about male homosexuals has been that

they are consistently “feminine” as children (Bailey & Zucker, 1995; Lippa, 2010). The Bailey

and Zucker (1995) study found that about three fourths of homosexual male adults were

“feminine” boys (defined as boys who were uninterested in sports or rough play, desired to

be girls, or had a reputation as a “sissy”), a far greater rate than in the general population

of males. The researchers interpreted these findings as further support for the biological

foundations of sexual orientation. Of course, those differences in childhood behavior could

also have been the result of attention and other forms of reinforcement from the social envi-

ronment. It is a very difficult task to separate the environmental influences on any aspect

of behavior from the biological ones. One thing is certain: The issue of what causes sexual

orientation will continue to generate research and controversy for a long time to come.

Human Sexual Behavior

phase 1:

excitement

phase 2:

plateau

phase 4:

resolution

females: outer vagina swells and outer lips flush due to ↑blood flow,

clitoris retracts under clitoral hood

males: penis becomes more erect, may release a few drops of seminal fluid

females: clitoris

swells, vaginal

lips open,

vagina moistens

males: penis

becomes erect,

testes pull up,

scrotum tightens

phase 3:

orgasm

shortest stage, consists of series of rhythmic muscular contractions

females can experience multiple orgasms; males typically only have one

orgasm that results in release of seminal fluid/sperm

Masters and Johnson identified four stages of the human sexual-response cycle

through direct observation and measurement; study was highly controversial

return of the body to prearousal state; males have a refractory period

during which another orgasm is not possible

beginning of sexual

arousal/preparation

for intercourse (↑

pulse/blood

pressure/breathing

sexual-response rate)

stages are similar

in both females

and males

but not identical

(see Figs. 10.3

and 10.4)

nipples harden/become

erect in both sexes

sexual orientation

person’s sexual attraction

and affection for members

of the opposite or same sex

differences in

sexual behavior

Kinsey pioneered the study of different types of sexual behavior

through face-to-face surveys; study was highly controversial;

sampling/representativeness questioned

the Janus Report (first large-scale survey since Kinsey)

examined both normal and deviant sexual behavior

results from the National Survey of Sexual Health and Behavior (NSSHB) in 2010 suggests

vaginal intercourse is most common during the reproductive years but a variety of other

nonreproductive sexual behaviors also occur; condom use is highest during adolescence

and drops off significantly in early adulthood

key concepts

sexual orientation is likely the product of both biology

(i.e., brain structure, genetics) and environment;

presence of biological foundations has implications

for societal definitions of diversity versus deviance

heterosexuality: attraction to

members of the opposite sex; most

common and socially acceptable

bisexuality: attraction to

members of both sexes

asexuality: lack of sexual

attraction to anyone, or a

lack of interest in sexual

activity

homosexuality: attraction to

members of one’s own sex

suggested sexual orientation

occurred on a continuum, not

an either/or basis

Concept Map L.O. 10.6, 10.7, 10.8

Interactive

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