________ has been referred to as the "common cold" of psychological problems

Operant conditioning is similar to the principle of natural selection in that an individual's behaviors that are _____ tend to increase in frequency, while behaviors that are _______ tend to decrease in frequency.

Fill in the blank(s) with the appropriate word(s).

To measure the validity of a psychological test, what might an investigator try to determine?

a. How many psychologists use the test and consider it helpful b. How many of the items on the test are easy, intermediate, or difficult c. How consistent people's scores are from test to retest d. How well the scores predict some other behavior