When memories are stored, physical changes take place in brain activity and in the nerve cells. These physical changes are called

Why do researchers in the area of mental imagery need to be concerned about experimenter expectancy?

a. Experimenters might somehow convey their hypotheses to the participants. b. Experimenters typically expect participants to perform very well on imagery tasks. c. When experimenters expect a certain outcome in their research, the participants unconsciously produce results that contradict this expectancy. d. Experimenter expectancy typically increases the magnitude of individual differences.

Sampling error is assumed

a. only when the F ratio is calculated b. only when the t ratio is calculated c. only when the Pearson r is significant d. whenever samples are measured