1. Kinds of evidence Positive Evidence:example utterances that occur in the input Which model the grammatical utterances in the language. Negative Evidence:correction and other behavior on the part of the adult that explicitly tells the child what is ungrammatical about their utterance. Indirect Negative Evidence: utterances and other behavior on the part of the adult that indirectly tell the child that something about their utterance is ungrammatical.

2. Example of Direct Negative Evidence (McNeill, 1966) Mother:No, say “nobody likes me.” Child:Nobody don’t like me. [Eight repetitions of this dialogue follow] Mother:No, now listen carefully, say “NOBODY LIKES ME” Child:Nobody don’t like me. Child:Oh! Nobody don’t likes me.

3. Child: Want other one spoon, Daddy. Father: You mean, you want THE OTHER SPOON. Child: Yes, I want other one spoon, please, Daddy. Father: Can you say "the other spoon"? Child: Other... one... spoon. Father: Say... "other". Child: Other. Father: "Spoon". Child: Spoon. Father: "Other... Spoon". Child: Other... spoon. Now give me other one spoon? Another Example of Direct Negative Evidence (Braine, 1971)

4. Other kinds of evidence (Marcus, 1993) Child:The ball fell down Parent:The ball fell down Repetition (verbatim) Positive evidence  only tells the child what is grammatical Recast (modification) Child:The ball falled down Parent:The ball fell down Indirect Negative Evidence  tells the child something is ungrammatical

5. Topic Extension Child:The ball falled down Parent:Yes it did, and then what happened? Incorrectly reinforces the child’s error Explicit approval Child:The ball falled down Parent:Yup. Incorrectly reinforces the child’s error

6. Clarification question Child:The ball falled down Parent:What was that? Ambiguous, not very useful evidence. Non sequiturs Child:The ball falled down Parent:…?... Ambiguous, not very useful evidence.