Identifying formulas in first language acquisition

With the increase in interest in formulas, or apparently non-productive utterances in children's speech, a range of definitions has emerged and sometimes conflicting criteria have been proposed for their identification. These definitions of formulas are compared, and the criteria of Brown (1973), Wong Fillmore (1976), Peters (1983) and Plunkett (1990) for the recognition of formulas are reviewed. A preference rule system is proposed, which distinguishes necessary, typical and graded conditions for the recognition of formulas. Using these conditions, some of the formulas found in the data of one child acquiring Irish between 1;4 and 2;1 are examined. Issues such as length of units, frequency of occurrence and appropriateness of use are discussed. The methods developed in this study could be used to assess the importance of formulas in the language acquisition of other children.