Kinds of evidencePositive Evidence: example utterances that occur in the inputWhich model the grammatical utterances in the language.

Negative Evidence: correction and other behavior on the partof the adult that explicitly tells the child what is ungrammaticalabout their utterance.

Indirect Negative Evidence: utterances and other behavior onthe part of the adult that indirectly tell the child that somethingabout their utterance is ungrammatical.

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.

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)

Other kinds of evidence (Marcus, 1993)

Child: The ball fell downParent: The ball fell down

Repetition (verbatim)

Positive evidence only tells the child what is grammatical

Recast (modification)

Child: The ball falled downParent: The ball fell down

Indirect Negative Evidence tells the child something is ungrammatical

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 downParent: Yup.

Incorrectly reinforces the child’s error

Clarification question

Child: The ball falled downParent: What was that?

Ambiguous, not very useful evidence.

Non sequiturs

Child: The ball falled downParent: …?...

Ambiguous, not very useful evidence.