Motivation consists of external influences on behavior, such as rewards, social evaluations, rules, and responsibilities.

Paula maintained her normal weight during her freshman year in college. during her sophomore year, she moved into an apartment with two friends who are overweight. the three regularly enjoy high-calorie meals together, and paula has gained more than twenty pounds. she wants to lose weight, but it seems as if, whenever she plans to prepare a healthful, low-calorie meal, her roommates come home with a box of pizza or take-out burgers and fries. what type of influence are her friends having on her behavior? social undermining moral support emotional encouragement informal persuasion social undermining