The critical role of group studies in neuropsychology: comprehension regularities in Broca's aphasia

We reexamine the empirical record of the comprehension abilities of Broca's aphasic patients. We establish clear, commonly accepted, selection criteria and obtain a pool of results. We then subject these results to a detailed statistical analysis and show that these patients comprehend certain canonical sentences (actives, subject relatives, and clefts with agentive predicates) at above-chance levels, whereas comprehension of sentences that contain deviations from canonicity (passives, object-gap relatives, and clefts) is distinct and is at chance. That the latter is the case, and patients indeed guess at such structures, we show by comparing the distribution of individual results in passive comprehension to that of a model for such guessing-an analogous series of tosses of an unbiased coin. The two distributions are virtually identical. We conclude that the group's performance is stable, and well-delineated, despite intersubject variation whose source is now identified. This means that certain comprehension tests may not always be used for the diagnosis of individual patients, but they do characterize the group. It also means that group studies are not just a valid option in neuropsychology; they are a must, since demonstrations like ours indiciate very clearly that single-case studies may be misleading. As we show, the findings from any one patient, without the context of a group, may give a distorted picture of the pathological reality. Our conclusions thus promote studies of groups of brain-damaged patients as a central tool for the investigation of brain/behavior relations.     

Comprehension regularity in Broca's aphasia? There's more of it than you ever imagined.

We analyze the comprehension data in Broca's aphasia, pooled together by Berndt, Mitchum, and Haendinges (1996). We show that once analyzed properly, these data have statistical structure that is very similar to that revealed by the analysis in Grodzinsky, Pinango, Zurif, and Drai (1999). The suggestion that the latter authors doctored the data to obtain a desired outcome is as false as the claim that the data in Berndt et al. show no regularity. Comprehension scores in Broca's aphasia do have statistical structure, which correlates with syntactic structure. Thus, the role of Broca's area and its vicinity in language processing can be made more precise.     

The Slingshot Argument: An Improved Version

In the paper I exploit Frege's notions of sense and synonymity in order to amend the slingshot argument. The main emendation is to replace the assumption about logical equivalence by an assumption about synonymity. While the replaced assumption begs the question about the reference of sentences, the replacing assumption has much more theoretical support from Frege's general conception of sense and reference and the relation between them. In the paper I use a specific notion of synonymity which I believe is faithful to Frege's discussion of the subject. I notice that if a stronger (and to my mind implausible) notion of synonymity is used, my version of the argument fails. The failure is explained by showing that this stronger notion of synonymity enables the assignment of facts, and not truth values, as the references of sentences.     

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.     

The Phenomenal Sorites and Response Dependence 1

Natural-kind essentialism faces an important but neglected difficulty: the problem of complex essences (PCE). This is the question of how to account for the unity of an instantiated kind-essence when that essence consists of multiple distinct properties, some of which lack an inherent necessary connection between them. My central goal here is to propose an essentialism-friendly solution to this problem. Along the way I also employ some points from that solution to argue for the necessary truth of essentialism (necessary, that is, in all possible worlds in which there are material objects), and to support the essentialist ontology of laws over and against a major rival.     

Externalism and Identity

The main aim of this paper is to show that there is one version of supervenience of the mental on the physical which is entailed by token-token identity (I call this version change-supervenience); and to establish that of the other better known versions of supervenience in the literature (which I call difference-supervenience), none are so entailed. One consequence of this is that Burge's thought experiments while successful in refutingdifference-supervenience cannot in themselves refute identity thesis. However, the introduction of change supervenience leads me to devise an analogous thought experiment against change-supervenience, thus refuting identity thesis as well.