The defining features view of object classification works well for natural objects but breaks down for mathematical categories, such as "square" or "triangle."

A patient is prescribed a medication and is told that the only side-effect is that the medication suppresses REM sleep. After finishing the medication, what might the patient expect in terms of a sleep change?

a. REM rebound b. narcolepsy c. sleeptalking d. REM behavior disorder

What may have been the most important factor leading to the reemergence of dominant hierarchies in humans?

a. Compassion. b. Stress hormones. c. Agriculture. d. Democracy.