Todd R. Haskell1 & Maryellen C. MacDonald2
1 University of Southern California & 2 University of Wisconsin, Madison
Distributional information --- e.g., the frequency of word or phoneme co-occurrences --- plays an important role in phonological production (Dell, Reed, Adams & Meyer, 2000), but most accounts of grammatical encoding have not posited a large role for distributional information. We examined this issue in the case of producing subject-verb agreement, a component of grammatical encoding. In English, which has strong word-order constraints, the verb and subject noun are typically adjacent (about 80% for declarative sentences in the Wall Street Journal corpus). If agreement computations make use of this distributional information, verbs will tend to agree with the nearest noun --- a "proximity" constraint.
Agreement "attraction" errors occur when the verb agrees with a non-subject noun within the subject noun phrase, e.g., "The key to the cabinets were missing". Vigliocco & Nicol (1998) found no difference in the rate of attraction errors for declarative sentences such as "The helicopter for the flights is safe" (where errors could be attributed to proximity of "flights" to the verb) vs. questions such as "Is the helicopter for the flights safe?" (where the non-subject noun is distant from the verb). This result argues against a proximity constraint in agreement. However, subtle agreement constraints can be obscured by strong grammatical and semantic cues (Haskell & MacDonald, 2001). We decided to look for proximity effects in a case where the usual cues to agreement are absent --- disjunctions of nouns with differing number, such as "the hat or the gloves". Here either noun could potentially control agreement. We used a game-playing task with picture cards to elicit questions such as "Can you tell me whether the hat or the gloves is/are red?" (verb follows the two nouns), or "Is/Are the hat or the gloves red?" (verb precedes the nouns). In both cases, participants overwhelmingly produced agreement with the noun closest to the verb. Moreover, the proximity effect was significantly larger in the verb-precedes than the verb-follows condition, suggesting a distributional origin to the effect: When the verb precedes the subject in English, the subject noun and verb are overwhelmingly adjacent, whereas when the verb follows the subject there is frequently intervening material. Thus, proximity is a more reliable distributional cue when the verb precedes the subject than when it follows it.
These findings suggest that distributional information plays a role in grammatical encoding as well as phonological encoding, and that similar mechanisms are important in both domains.
References
Dell, G., Reed, K., Adams, D., & Meyer, A. (2000). Speech errors, phonotactic constraints, and implicit learning: A study of the role of experience in language production. Journal of Experimental Psychology: Learning, Memory and Cognition, 26, 1355-1367.
Haskell, T., & MacDonald, M. (2001). Semantic and phonological factors in subject-verb agreement. Manuscript submitted for publication.
Vigliocco, G., & Nicol, J. (1998). Separating hierarchical relations and word order in language production: Is proximity concord syntactic or linear? Cognition, 68, B13-B29.