Children with specific language impairment (SLI) are known to display persistent difficulties with inflectional morphology--in particular, the overuse of unmarked grammatical forms (i.e., zero-marking). Yet, several recent studies have shown that English-speaking children with SLI, like their normal language peers (NL), demonstrate a considerable degree of productive language abilities (e.g., Bishop, 1994; Loeb & Leonard, 1991; Oetting & Horohov, 1997). In this study, we explore productivity in the English past tense in school-age children with SLI (N= 31) and NL (N = 31) who were equivalent as a group in chronological and mental age. Although children in both groups produced a range of error types, the children with SLI produced significantly more errors, with a greater proportion resulting from zero-marking (e.g., go) than suffixation (e.g., goed). Item analyses indicated that suffixations and zero-markings were predicted by item frequency, phonological features of stems, and similarity relationships across items (i.e., neighborhood structure) in both groups, yet children with SLI were more sensitive to item phonology than their NL peers. Results are interpreted in light of the predictions of dual- versus single-mechanism models of morphological productivity. Implications for accounts of SLI are discussed.

Selective deficits in aphasic patients' grammatical production and comprehension are often cited as evidence that syntactic processing is modular and localizable in discrete areas of the brain (e.g., Y. Grodzinsky, 2000). The authors review a large body of experimental evidence suggesting that morpho-syntactic deficits can be observed in a number of aphasic and neurologically intact populations. They present new data showing that receptive agrammatism is found not only over a range of aphasic groups, but is also observed in neurologically intact individuals processing under stressful conditions. The authors suggest that these data are most compatible with a domain-general account of language, one that emphasizes the interaction of linguistic distributions with the properties of an associative processor working under normal or suboptimal conditions.

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Most of us would like to believe that the different patterns of language breakdown observed in aphasic patients reflect the way that the human mind and brain are organized for language. However, because so much modern research on aphasia has been carried out in English, it is difficult to separate universal mechanisms from language-specific content. Crosslinguistic com-parisons permit us to disentangle these confounds, while we address one of the most important issues in cognitive neurobiology, the issue of behavioral and neural plasticity:How many different forms can the language processor take under a range of normal and abnormal conditions? We must have an answer to this question if we want to understand what the neural mechanisms responsible for language really are and really do.The nine papers presented within this special crosslinguistic issue of Brain and Language provide important new information about universal and language-specific patterns of sparing and impairment, in nonfluent "agrammatic" Broca's aphasics and in fluent patients with a diagnosis of Wernicke's aphasia. These crosslinguistic studies fall into two categories: (1) research in which language type is treated as an independent variable, by conducting the same experiment with equivalent materials in two or more different languages, and (2) research in which language type is treated as a natural experiment, using the peculiar characteristics of a single language to answer a question that would be difficult to ask in (for example) English. Studies applying one or both of these cross-linguistic methods have yielded six basic findings, summarized briefly as follows.(1) Crosslinguistic variation: First, the papers in this issue (and related crosslinguistic studies by these investigators and other research groups -see Menn and Obler, 1990) clearly demonstrate that the "same" aphasic syndromes look very different from one language to another.Indeed, language differences account for more variance than patient group differences in many of our crosslinguistic experiments to date (e.g

We present the first direct comparison of language production in brain-injured children and adults, using agecorrected z scores for multiple lexical and grammatical measures. Spontaneous speech samples were elicited in a structured biographical interview from 38 children (5-8 years of age), 24 with congenital left-hemisphere damage (LHD) and 14 with congenital right-hemisphere damage (RHD), compared with 38 age-and gender-matched controls, 21 adults with unilateral injuries (14 LHD, 7 RHD), and 12 adult controls. Adults with LHD showed severe and contrasting profiles of impairment across all measures (including classic differences between fluent and nonfluent aphasia). Adults with RHD (and three nonaphasic adults with LHD) showed fluent but disinhibited and sometimes empty speech. None of these qualitative or quantitative deviations were observed in children with unilateral brain injury, who were in the normal range for their age on all measures. There were no significant differences between children with LHD and RHD on any measure. When LHD children were compared directly with LHD adults using age-corrected z scores, the children scored far better than their adult counterparts on structural measures. These results provide the first systematic confirmation of differential free-speech outcomes in children and adults, and offer strong evidence for neural and behavioral plasticity following early brain damage.For more than 3000 years, we have known that language production can be damaged or lost following brain injury (O'Neill, 1980), and since the 1860's we have also known that language deficits are overwhelmingly more likely if the injury involves the left side of the brain (Cotard, 1868, cited in Woods & Teuber, 1978Bernhardt, 1897). To account for these longstanding and well-documented facts, it seems reasonable to hypothesize that the left side of the human brain contains some kind of specialized organ for language and speech (Fodor, 1983;Newmeyer, 1997;Pinker, 1994; Rice, 1996), one that should be observable in its approximate adult form at birth, not unlike the liver or the heart. This hypothesis is buttressed by studies showing that adult-like structural asymmetries between the left and right sides of the brain are evident at and before birth (Witelson & Pallie, 1973), and by electrophysiological studies showing that the left side of the brain is significantly more active in response to complex auditory stimuli (including speech) in the human infant (Molfese & Segalowitz, 1988).In view of all these facts, it is difficult to understand why adults and children who acquired unilateral brain injuries early in life perform so well on language tasks (Bates, 1999;Bates, Vicari, & Trauner, 1999;Eisele & Aram, 1995;Elman et al., 1996;Feldman, Holland, Kemp, & Janosky, 1992; Nass, in press;Stiles, Bates, Thal, Trauner, & Reilly, 1998;Vargha-Khadem, Isaacs, & Muter, 1994;Vicari et al., 2000). In fact, in the absence of confounding factors (e.g., intractable seizures-Vargha-Khadem, Isaacs, van der Werf, Robb, ...