Container neophobia and the rat's preference for earned food.
D000818:Animals; D000830:Animals, Laboratory; D003216:Conditioning, Operant; D004435:Eating; D004777:Environment; D005106:Exploratory Behavior; D005239:Fear; D005508:Food Deprivation; D005518:Food Preferences; D008297:Male; D051381:Rats; D012201:Reward