Comprehension outscores production in language acquisition: Implications for Theories of Vocabulary Learning

It is well-documented that children comprehend many more words than they are able to produce. Without exception, a child appears to understand various words that they do not use in their own speech. These results are used to test three different theories of speech perception. Motor theory assumes that motor processes are necessarily recruited for speech perception. A common representation theory claims that the same representation exists for both comprehension and production. Comprehension can be viewed as a recognition task whereas production can be considered a recall task, and recall is necessarily more difficult than recognition. The third theory assumes that speech perception and speech production and their acquisition cannot be based on the same underlying representation. Speech perception follows prototypical pattern recognition processes whereas speech production involves intricate motor processes that attempt to match a speech target. We analyze data from the MacArthur-Bates Communicative Development Inventories (CDI) to determine 1) if difficulty of articulation and parental input frequency influence perception and production equivalently and 2) assess whether equivalent representations can account for perception and production. The results falsify motor theory and common representation theory and support the pattern recognition account of speech perception.