SD-squared: on the association between semantic dementia and surface dyslexia

Within the connectionist triangle model of reading aloud, interaction between semantic and phonological representations occurs for all words but is particularly important for correct pronunciation of lower frequency exception words. This framework therefore predicts that (a) semantic dementia, which compromises semantic knowledge, should be accompanied by surface dyslexia, a frequency-modulated deficit in exception word reading, and (b) there should be a significant relationship between the severity of semantic degradation and the severity of surface dyslexia. The authors evaluated these claims with reference to 100 observations of reading data from 51 cases of semantic dementia. Surface dyslexia was rampant, and a simple composite semantic measure accounted for half of the variance in low-frequency exception word reading. Although in 3 cases initial testing revealed a moderate semantic impairment but normal exception word reading, all of these became surface dyslexic as their semantic knowledge deteriorated further. The connectionist account attributes such cases to premorbid individual variation in semantic reliance for accurate exception word reading. These results provide a striking demonstration of the association between semantic dementia and surface dyslexia, a phenomenon that the authors have dubbed SD-squared.     

Defending the Possibility of Knowledge

In this paper, I propose a solution to Fitch’s paradox that draws on ideas from Edgington (Mind 94:557–568, 1985), Rabinowicz and Segerberg (1994) and Kvanvig (Noûs 29:481–500, 1995). After examining the solution strategies of these authors, I will defend the view, initially proposed by Kvanvig, according to which the derivation of the paradox violates a crucial constraint on quantifier instantiation. The constraint states that non-rigid expressions cannot be substituted into modal positions. We will introduce a slightly modified syntax and semantics that will help underline this point. Furthermore, we will prove results about the consistency of verificationism and the principle of non-omniscience by model-theoretical means. Namely, we prove there exists a model of these principles, and delineate certain constraints they pose on a structure in which they are true.     

Spatial coordinates and reading: Comments on Monk (1985)

Subjects are able to process some texts when they are presented, word-by-word, in a single physical location. As differential spatial information is not available in this task, Monk (1985a) argues that it need not be derived in normal reading. We suggest this conclusion is unwarranted, because subjects make large and very accurate regressive saccades to regions of previously fixated text. Without a representation of spatial coordinates this should not occur.     

Some experimental analogues of obsession

This paper is an attempt to analyse some of the features of obsessional neurosis in terms of learning theory. First, the syndrome is described and found to have three main features: brooding, strong impulses to do unacceptable things, and ritualistic, defence-substitute activities. Second, the classical psychoanalytic explanation of the etiology of obsession is reviewed. This theory locates the source of conflict in the anal stage, but fails to give a satisfactory account of the precipitating conditions and of the cause for the persistence or fixation of the neurotic responses. In the third section both the precipitating conditions and the fixation conditions are analysed in terms of factors shown to be operative in animal learning experiments.