1. Semantic Processing and Irregularly Inflected Forms Michele Miozzo & Peter Gordon Columbia University Introduction Recent models of lexical representation suggest that semantic processing is involved in the production and comprehension of irregularly inflected forms such as feel- felt, or break-broke. According to these models, irregular inflections and semantic processing should show parallel associations of processing and breakdown The single-level connectionist model of Joanisse and Seidenberg (1999) proposes that “lesions” of semantic memory will lead to deficits in processing of irregularly inflected words, but not regulars The dual model of Ullman (2001) proposes that language is subserved within the declarative/ procedural distinction in memory. Deficits in semantic/declarative memory should go hand-in-hand with specific deficits on irregular but not regular inflections Patient VP showed a semantic processing impairment Is VP’s production of irregular forms also impaired? Patient VP College educated, Native English Speaker 86 yrs old, right-handed, female Secretary for scientific Lab November 2001, hospitalized after intraparenchymal, lobar hemorrhage Left superior parietal lesion (CT Scan) No grammatical errors detected in spontaneous speech Auditory grammaticality judgment task: (EX: “They want to meet the girl that you said were pretty”) (10/10 correct) Reading aloud words and non-words was intact Writing and oral spelling mildly impaired for both words and non-words Picture visual recognition intact (EX: Able to recognize whether two pictures represented a target object from different perspectives) Tests of Semantic Memory VP performed poorly in semantic memory tasks demanding the retrieval of detailed semantic information VP’s poor verbal definitions of auditorily presented concepts (Table 2) and her numerous semantic errors in the picture naming task (Table 3) also suggest impaired semantic memory. Table 2 Examples of VP’ s verbal descriptions ConceptVP’s Description MazeMade out of ground dirt. I’ve gone to one of these. GhostHavent’s heard much about ghosts. Nothing special. A spiritual character. Chisel Chiseling out something… BeaverAn animal. They burrow, so they dig out from underground… messing up a lot of ground. Table 3 Examples of VP’ s semantic errors* in picture naming TargetVP’s Response Hammer“Screwdriver” Hamburger“Pie” Bus“Van” Guitar“Violin” Mustache“Wig” Dinosaur“Giraffe” Helicopter“Plane” Strawberries“Potatoes” Eskimo“Igloo” * Semantic errors represented 58% (38/65) of VP’s erroneous responses VP’s Production of Regular and Irregular Inflected Forms Elicitation Task: Inflected form is given in response to citation form presented orally by experimenter (EX: walk – “walked”) Tasks included: past tense, past participle, and noun plural. Equal numbers of regular and irregular forms matched for frequency and imageability presented in each task. VP performed as well as age-matched controls with both regular and irregular forms (Table 4). Table 4 Inflection Task % Correct responses n items VP Control Past tense Regular formswalk “walked”95 99% 98% Irregular formseat “ate”95 97% 96% Past participle Regular formswalk “walked”97 99% 99% Irregular formseat “eaten”97 95% 97% Noun plural Regular formsmouse “mice”21100%100% Irregular formsmink “minks”21 90%100% Conclusions VP’s clear-cut dissociation between impaired semantic processing and preserved production of irregular forms challenges the view that semantic mechanisms are critical for the retrieval of irregular forms. Rather, VP’s data support a more modular view in which semantic processing is not selectively involved in the retrieval of irregular forms. References Hillis, A. E., & Caramazza, A. (1995). Cognitive and neural mechanisms underlying visual and semantic processing: Implications from “optic aphaisa.” Journal of Cognitive Neuroscience, 7, 457-478. Joanisse, M. F., & Seidenberg, M. S. (1999). Impairments in verb morphology after brain injury: A connectionist model. Proceedings of the National Academy of Sciences, 96, 7592-7597. Miozzo, M. (2003). On the processing of regular and irregular forms of verbs and nouns: Evidence from neuropsychology. Cognition, 87, 101- 127. Riddoch, M. J., & Humphreys, G. W. (1993). BORB Birmingham object recognition battery. Hove: Erlbaum. Ullman, M. T. (2001). A neurocognitive perspective on language: the declarative/procedural model. Nature Reviews Neurosicence, 2, 717-726. “To which item is the top picture more related?” Picture-picture Matching Task (Hillis & Caramazza, 1995; Riddoch & Humphreys, 1993). walk stroll run Verb synonym task (Miozzo, 2003) “Is walk more related to stroll or to run?” Table 1 % Correct responses: Semantic memory tasks Controls VP Picture Matching 1 100% 78% Picture Matching 2 92%70% Synonym judgment 99%86% A case study in the dissociation of semantic processing and irregular inflection