Dr. Keller has individuals run on a treadmill for 0, 15, or 30 minutes and then measures their self-reported mood. In this hypothetical study, the independent variable is:

You see an advertisement for a method of learning a foreign language that seems simple—just rev up the iPod and fall asleep. The accompanying product description cites proof that people can learn while asleep

Being a good psychological detective, what question would you ask about the offered proof? a) Did the individuals actually dream about the foreign language? b) What did the EEG indicate about the participants' level of sleep? c) Did the researchers use only long sleepers who would spend more time with the tapes? d) Were study breaks included in the tape to provide greater comprehension of the material?

A researcher would like to know whether his new dog training program is effective. He tests a group of dogs before they start the program, and then again afterwards. What research design has he used?

a. one-group pretest-posttest design b. pretest-posttest control group design c. posttest only control group design d. nonequivalent control group design