To examine potential gender differences in the qualities individuals seek in their romantic partners, HaeJin compares the personal ads placed by men and women. HaeJin is conducting a(n)

Tess agrees to sleep in an artificial setting for three nights so that researchers can obtain information about her brain and muscle activity during sleep. She is taking part in a research method called _________

a. a single-blind study b. a double-blind study c. naturalistic observation d. laboratory observation

Endorphins are the neural transmitters that __________

a) control your muscles. b) generate pain sensations. c) act as a natural painkiller. d) excite the ventral horn of the spinal cord.