The Development of Simile Comprehension: From Similarity to Scalar Implicature.

Similes require two different pragmatic skills: appreciating the intended similarity and deriving a scalar implicature (e.g., "Lucy is like a parrot" normally implies that Lucy is not a parrot), but previous studies overlooked this second skill. In Experiment 1, preschoolers (N = 48; ages 3-5) understood "X is like a Y" as an expression of similarity. In Experiment 2 (N = 99; ages 3-6, 13) and Experiment 3 (N = 201; ages 3-5 and adults), participants received metaphors ("Lucy is a parrot") or similes ("Lucy is like a parrot") as clues to select one of three images (a parrot, a girl or a parrot-looking girl). An early developmental trend revealed that 3-year-olds started deriving the implicature "X is not a Y," whereas 5-year-olds performed like adults.