One of the earliest laws concerning the learning of skills was Edward Thorndike's observation that actions rewarded tend to be repeated, while those actions that are punished tend not to be repeated. This observation is called the Law of

Osteoporosis affects what percentage of women over 60?

a) 10 percent b) .5 percent c) 25 percent d) 50 percent

Which of the following is a common feature of typical monoamine-related hallucinogens?

a. rapid tolerance to their subjective effects b. cross-tolerance to the effects of the drugs in this group c. the absence of any notable abstinence symptoms upon cessation of use following chronic use d. only a and b above