A new empirical angle on the variability debate: quantitative neurosyntactic analyses of a large data set from Broca's aphasia

Behavioral variation in Broca's aphasia has been characterized as boundless, calling into question the validity of the syndrome-based schema and related diagnostic methods of acquired language disorders. More generally, this putative variability has cast serious doubts on the feasibility of localizing linguistic operations in cortex. We present a new approach to the quantitative analysis of deficient linguistic performance, and apply it to a large data set, constructed from the published literature: Comprehension data of 69 carefully selected Broca's aphasic patients, tested on nearly 6000 stimulus sentences, were partitioned in different ways, and subjected to a series of analyses. While a certain amount of variability is indeed evident in the data, our quantitative analyses reveal a highly robust selective impairment pattern for the group: the patients' ability to analyze syntactic movement is severely compromised, in line with the Trace-Deletion Hypothesis. Further analyses suggest that patients' performance on no-movement sentence types exhibits less variation than on sentences that contain movement. We discuss the clinical and theoretical implications of our results.     

Agrammatic comprehension of relative clauses

Four hypotheses that attempt to account for the comprehension deficit in agrammatism are put to an empirical test. The interest in them is in that they all view the deficit as highly selective. The first, proposed by D. Caplan and C. Futter (1986, Brain and Language, 27, 117-134), argues that agrammatic patients cannot carry out normal syntactic analysis beyond the category label of each incoming lexical item and are reduced to the use of a cognitive strategy that commends assignment of thematic roles to noun phrases merely by their linear position in the string. A second, less radical hypothesis (Y. Grodzinsky, 1986a, Brain and Language, 27, 135-159), accounts for the deficit differently, by deleting a particular kind of syntactic object (trace) from the otherwise normal representation, and augmenting the resulting, underspecified representation by a strategy, whose use is quite restricted. A third account that is tested contends that agrammatic aphasics fail to comprehend perceptually complex constructions, where the metric for complexity is determined by results obtained from comprehension tests of normal listeners. The fourth account (M. F. Schwartz, M. C. Linebarger, E. M. Saffran, and D. S. Pate, 1987, Language and Cognitive Processes, 2, 85-113) argues that the thematic transparency of a construction (whether or not thematic roles are assigned directly to positions) is the best predictor of the manner by which agrammatics can handle it. An empirical test is thus constructed, both to extend the evidential basis concerning the comprehension skills of these patients and to distinguish between the accounts. Four types of relative clauses are presented to the patients, where embedding type (center vs. right) is one variable, and location of gap (subject vs. object position) is the other. The patients are tested in a sentence-picture matching paradigm. The finding, that is rather robust, is that gap location is the best predictor of agrammatic performance: the patients perform well above chance on both types of subject gap relatives, and at chance levels on object gaps. It is then shown that the Trace-Deletion Hypothesis (Grodzinsky, 1986a) is the only one among the accounts considered that is compatible with these data.     

Frontal lobe functions in attention deficit disorder with and without hyperactivity: A review and research report

We review 22 neuropsychological studies of frontal lobe functions in children with attention deficit disorder with and without hyperactivity (ADD/+H,ADD/-H). Some measures presumed to assess frontal lobe dysfunctions were not reliably sensitive to the deficits occurring in either form of ADD. Tests of response inhibition more reliably distinguished ADD/+H from normal children. Where impairments were found on other tests between ADD and normal subjects, they were highly inconsistent across studies and seemed strongly related to age of the subjects and possibly to the version of the test employed. Other methodological differences across studies further contributed to the discrepant reports. The co-morbidity of other disorders, such as learning disabilities (LD) and conduct problems, with ADD may be an additional confounding factor in some, though not all, of these studies. In a separate study, children with ADD/+H (n=12) were then compared on frontal lobe tests to three other groups: ADD/-H (n=12), LD but no ADD (n=11),and normal children (n=12) statistically covarying for differences in conduct problems across groups. Most measures did not distinguish among these groups. Both ADD groups made more omission errors on a Continuous Performance Test (CPT) than the normal group. All three clinical groups performed more poorly on the word and interference portions of the Stroop Test. Thus, while both types of ADD share some apparent similarities in deficits on a few frontal lobe tests in this study, the totality of existing findings suggests an additional problem with perceptual-motor speed and processing in the ADD/-H group.This research was supported by NIMH grant MH41464 and by funds from the Department of Psychiatry, University of Massachusetts Medical Center. The authors are grateful to Judy Tessier and Ellen Mintz-Lennick for their assistance with some of the data collection and scoring. The comments of Virginia Douglas on an earlier draft of this paper are greatly appreciated.     

Equity of access: Adaptive technology

In this age of information technology, it is morally imperative that equal access to information via computer systems be afforded to people with disabilities. This paper addresses the problems that computer technology poses for students with disabilities and discusses what is needed to ensure equity of access. particularly in a university environment. A version of this paper was presented at ETHICOMP98, the Fourth International Conference on Ethical Issues of Information Technology. March 25–27, 1998, Erasmus University, the Netherlands. Frances S. Grodzinsky is a Professor of Computer Science and Information Technology. Her area of research is computer ethics.     

The battle for Broca's region

The intense effort to characterize Broca's region has produced many views on its anatomy and function. Here, we present the leading approaches and consider ways to adjudicate among them empirically. Anatomically, we focus on the cytoarchitecture of Brodmann areas 44 and 45, which constitute Broca's region. Functionally, we discuss four views: action perception, working memory, syntactic complexity and syntactic movement. We compare these views, reflect on how they can be distinguished experimentally and review relevant aphasia and functional magnetic resonance imaging (fMRI) studies. Although no single hypothesis accounts for all of the data, the role of Broca's region in language comprehension is best explained by the syntactic movement account. This conclusion opens the door for an attempt to define general principles for the neural representation of linguistic knowledge.