A study conducted by Douglas Carroll and his colleagues (1994) examined the relationship between socioeconomic status and health using grave markers. Which type of research was this?

To "see" gradual variations in shading, we rely on cells that respond best to ___ but to "see" abrupt changes in light versus dark, we rely on cells that respond best to ___

a. low frequency stimuli; sine wave gratings b. high frequency stimuli; low frequency stimuli c. sine wave gratings; Mach bands d. low frequency stimuli; high frequency stimuli

What has been shown to be related to the changes in marijuana consumption among high school students?

a) Social factors that foster marijuana use, such as joblessness or economic factors. b) Media images supporting cigarette smoking. c) Lowered purity of marijuana available in the market. d) Beliefs about the risks associated with marijuana smoking.