About _______________ of all adults have difficulty falling or staying asleep

An important potential problem with using symbols to represent a problem is that

a. people typically use at least twice as many symbols as they need. b. people usually construct a hierarchical tree diagram, even though they intended to use symbols. c. people insert the symbols into the wrong matrix. d. people have trouble translating words into the appropriate symbols.

The life-span development approach has which of the following goals?

a. Describe the physical changes that occur between birth and adolescence. b. Describe and explain behavior changes within an individual and differences between individuals from conception to death. c. Explain the results of learning from conception to death. d. Investigate the influence of heredity and environment upon individuals from conception to death.