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Interactions Between Type of Instruction and Type of Language Feature: A Meta-Analysis


  • We are grateful to the anonymous reviewers who provided constructive input and valuable feedback on an earlier version of the manuscript. We are particularly grateful for the information and guidance from one of the reviewers with particular expertise in conducting meta-analyses. Although the article has improved considerably from the input from all reviewers, we alone are responsible for any errors or omissions. A paper based on this research was presented at the annual meeting of the American Association for Applied Linguistics Conference 2008, Washington, DC.

concerning this article should be addressed to Nina Spada, Modern Language Centre, Ontario Institute for Studies in Education, University of Toronto, 252 Bloor Street West, Toronto, Ontario M5S 1V6, Canada. Internet:


A meta-analysis was conducted to investigate the effects of explicit and implicit instruction on the acquisition of simple and complex grammatical features in English. The target features in the 41 studies contributing to the meta-analysis were categorized as simple or complex based on the number of criteria applied to arrive at the correct target form (Hulstijn & de Graaff, 1994). The instructional treatments were classified as explicit or implicit following Norris and Ortega (2000). The results indicate larger effect sizes for explicit over implicit instruction for simple and complex features. The findings also suggest that explicit instruction positively contributes to learners’ controlled knowledge and spontaneous use of complex and simple forms.