The fact that the ability to control one's head develops before the ability to control one's legs illustrates the _____ principle

A researcher hypothesized that the drug amphetamine (a stimulant) improves learning

She explains her hypothesis to her participants and gives experimental group participants an amphetamine pill before they begin studying. Control group members get nothing. Later, she assesses how much each participant learned. Because of the hypothesis explanation and because the experimental group was given a pill that the other group did not receive, the experimental group will most likely expect to learn more. Thus, any observed differences between groups may reflect differences in expectation, not the actual effect of the drug, a problem known as the a. anthropomorphic error. b. research participant bias. c. courtesy bias. d. double-blind experimental effect.

A psychologist observes the confrontation between two rival neighborhood gangs from the window of an abandoned building. This method of collecting observations is best described as

a. experimental regression. b. naturalistic observation. c. controlled experimentation. d. clinical case study.