Direct negative evidence is a term used in the study of the acquisition of language. It describes the attempts of competent speakers of a language to guide the grammatical use of novice speakers, such as children.
Definition
Negative evidence in language acquisition consists of evidence that demonstrates which grammatical constructions in a language are ungrammatical. Furthermore, Saxton (1997) asserts that negative evidence supplies the " correct adult model" for novice speakers to avoid future grammatical mishaps. Negative evidence corrections, in whatever form they appear, necessarily follow immediately after an incorrect, often ungrammatical, utterance. Note that although parents often understand their children, and these production mistakes aren't usually egregious enough for the parent to not be able to correct it, negative evidence deals with the conventional standards of grammar in a language and the correct model of grammar structures, rather than communicative ones.
Direct negative evidence differs from indirect negative evidence in that it is explicitly presented to a language learner (for example, a child might be corrected by a parent) whereas indirect negative evidence is inferred from the absence of ungrammatical utterances in a given language. Though it is generally agreed that there is positive evidence (i.e. evidence that demonstrates grammatical linguistic constructions) in the language input, there is a dearth of direct negative evidence in the general language learner input since most native or veteran speakers produce grammatical as opposed to ungrammatical speech.
"No Negative Evidence" Problem
One of the difficulties surrounding language acquisition is that the language input is not rich enough for children to develop a correct grammar, otherwise referred to as the argument of the poverty of the stimulus. This is a commonly held position by nativists, who believe that there are innate mechanisms which facilitate language learning. The central idea of the poverty of the stimulus argument is that children could have multiple hypotheses about aspects of their grammar which are distinguishable only by direct negative evidence (or by hearing ungrammatical sentences and recognizing those sentences as ungrammatical). Supporters of the poverty of the stimulus argument then assert that because the negative evidence that is needed to learn language by the input alone does not exist, children cannot learn certain aspects of grammar from the input alone, and there must be some aspects of grammar which involve innate mechanisms.
The view that there is "no negative evidence" in the input is held by a number of researchers in the field of language acquisition who assert that if children are to learn language, then they must be able to learn language by solely examining the positive evidence that they do receive from the input since there is not enough negative evidence to be useful for language learning. Some propose that direct negative evidence would be necessary for children to develop a fully formed grammar, so it has also often been argued that children cannot learn a language by only receiving positive evidence, and that therefore there must be innate constraints on their biology which would allow them to learn language.
Examples of Direct Negative Evidence
Implicit negative evidence is a type of corrective feedback in which parental responses to a child's incorrect statements is indicative of the utterance's ungrammaticality. It is argued that there is a shortage of explicit direct negative evidence in the general input of learners. However, others have conducted studies that demonstrate that there is suitable implicit direct negative evidence present in parental responses to their children. There have been a number of studies regarding this type of evidence in which researchers have demonstrated that parents do respond differently when children utter grammatical or ungrammatical utterances.