Some researchers have posited a "natural" order of acquisition of English grammatical morphemes common to all learners of English as a second language, but no single cause has been shown for this phenomenon. This meta-analysis investigated whether a combination of five determinants (perceptual salience, semantic complexity, morphophonological regularity, syntactic category, and frequency) accounts for a large part of the total variance found in acquisition order. Oral production data from 12 studies over almost 25 years, together involving 924 subjects, were pooled. Multiple regression analysis showed that a very large portion of the total variance in acquisition order is explained by the combination of the five determinants. We suggest research on other potential contributing factors and discuss the need for similar research in other languages.

This meta-analysis pools data from 25 years of research on the order of acquisition of English grammatical morphemes by students of English as a second language (ESL). Some researchers have posited a ''natural'' order of acquisition common to all ESL learners, but no single cause has been shown for this phenomenon. Our study investigated whether a combination of 5 determinants (perceptual salience, semantic complexity, morphophonological regularity, syntactic category, and frequency) accounts for the variance in acquisition order. Oral production data from 12 studies, together involving 924 participants, were pooled to obtain weighted accuracy scores for each of 6 grammatical functors. Results of a multiple-regression analysis showed that a large portion of the total variance in acquisition order was explained by the combination of the 5 determinants. Several of these determinants, it was argued, can be seen as part of a broad conceptualization of salience.