Dissociations of language function in dementia: A case study

In this report we describe and attempt to characterize the deterioration in semantic knowledge occurring in a victim of a progressive dementing disease. The subject was unable to match even highly familiar naming words with their actual or pictured referents; instead, she consistently overextended verbal labels to closely associated distractors. The alteration in scope of referential meanings suggested by this overextension effect was apparently related to a breakdown in the structure of underlying categories. On a nonverbal match-to-sample procedure, for example, dogs were treated as exemplars of the cat family. Evidence for the breakdown of semantic knowledge was not limited to picture labeling paradigms. Thus, we found that the subject was unable to utilize semantic context in the written disambiguation of spoken homophones but could, at the same time, use even minimal syntactic cues as the basis for proper lexical selection. This last result was consistent with other lines of evidence pointing to the relative preservation of syntactic operations, in marked contrast to the semantic loss. The importance of this dissociation of function in organic pathology is considered from a number of perspectives, including its relevance to models of language organization in the brain.     

Some aspects of language comprehension in anterior aphasia

The competency of language comprehension was evaluated in three groups: anterior aphasics, posterior aphasics, and normal control subjects. Test material was divided into two sentence groups (Fill in the Blank and True/False) emphasizing either (1) semantic, “real world,” identity words or (2) syntactic, relational words, and one paragraph interpretation task. Matching auditory and visual (written) presentations were given. The control subjects performed almost flawlessly but many errors were made by each aphasia group. Qualitative study revealed a marked difference in the comprehension problem of the two groups. The anterior aphasic group performed well on semantically weighted sentences but made errors on syntactically weighted material, regardless of mode of presentation. In contrast, the posterior aphasics made almost the same number of errors on both types of material, regardless of mode of presentation. These findings support the concept of defective language comprehension in anterior aphasia and further suggest that the defect centers on the syntactical structures which are also poorly handled in expressive output.     

Extraversion and the orienting reaction habituation rate to visual stimuli

Eysenck's (1967) proposal that introversion is characterized by increased levels of activity in the cortico-reticular loop was treated in a series of experiments which compared high, middle, and low extraversion groups on the basis of OR habituation rate to visual stimulation. Generally, introverts were observed to have longer OR habituation rates to chromatic and word stimulation than extraverts as evidenced by cardiac, electrodermal, and vasomotor indices of habituation rate, a result which endorses Eysenck's hypothesis. Results are also discussed from the standpoint of individual differences in autonomic response.     

Investigative versus realistic Holland types and adjustment in theoretical engineering majors

This study tested the sensitivity of J. L. Holland's (Making vocational choices: A theory of careers, Englewood Cliffs, N.J.: Prentice-Hall, 1973) congruence method for predicting differential outcomes in the case of subtle person-environment congruence differences. This question is relevant to engineering programs, where students with adjacent Holland orientations of Investigative (I) and Realistic (R) aspire to complete theoretically oriented engineering majors, such as electrical and mechanical engineering. It was hypothesized that high congruence (e.g., I-type student in I-type engineering major) compared to moderately high congruence (e.g., R-type in I-type major) would result in more positive educational outcomes. A preliminary analysis verified that subgroups of I- and R-type students possessed similar scores on measures of general and math aptitude. Results on both outcome measures favored the high student-curriculum congruence hypothesis. I- compared to R-type subjects demonstrated greater persistence in their initial engineering major over a 2-year period and attained higher grades. Persistence findings replicated across two separate classes of entering students, but academic performance differences were not as consistent.     

The effects of symmetry and contour on recognition memory in children

Children in prekindergarten, kindergarten, and second grade were tested on a delayed match-to-sample task using abstract visual patterns. The patterns varied both in type of visual organization (unstructured, diagonally symmetrical, vertically symmetrical, and horizontally symmetrical) and in amount of contour. Following the initial memory task, we attempted to train half of the children at each grade by directing their attention to axes of symmetry; the other half of the children received a control task. Subsequently, the subjects were given a second delayed match-to-sample test. On both pre- and post-training trials, structure influenced performance, especially in the two younger groups. Vertical and horizontal symmetry generally facilitated performance in the prekindergarteners, while all three types of symmetry facilitated performance in the kindergarteners. In addition, children generally responded more accurately to patterns with lower levels of contour. They also made more like-contour than unlike-contour confusions, indicating that quantitative aspects of patterns were encoded. Group differences suggested that both processing capacity and memory increase during the age range studied. Finally, there was no indication that training improved performance at any age.     

Socially mediated fear reduction in rodents: Distraction,communication, or mere presence?

Two studies investigated why the presence of conspecifics reduces open-field fear. In Experiment 1 rats paired with another experimentally naive rat were not less fearful than alone controls. However, rats paired with a partner who had been preexposed to the open field exhibited fewer fear responses than alone controls. Since preexposed companions appeared to initiate more social interactions than nonpreexposed companions, it was argued that the preexposure effect could be the result of preexposed companions distracting actor rats from threatening stimuli. Experiment 2 tested this explanation by pairing socially sated or socially deprived rats with a socially sated or socially deprived companion. In accord with a distraction hypothesis, pairing two socially deprived rats produced the greatest fear reduction effects and also led to more social interaction than pairing socially sated rats. Alternative explanations involving conditioning and communication are discussed.     

Alexia and agraphia with spared spelling and letter recognition abilities

A patient with alexia and agraphia had intact spelling and comprehension of spelled words and used a letter-naming strategy to read and write. We propose that there is a graphemic area important for distinguishing graphemic features and for programming movements used in writing. In this patient this area was not functioning or did not have access to the area of visual word imagés. Therefore, he used an ideographic letter-naming strategy to verbally circumvent his disability and gain access to the area of visual word images.     

Ear asymmetries on a selective attentional task

To ascertain whether there are ear-hemisphere asymmetries of selective attention, signal stimuli (tonal sequences) were presented monaurally with and without complex maskers (music and speech). The right ear-left hemisphere was more disrupted by language maskers; the left ear-right hemisphere was more disrupted by music maskers. These results suggest that there are hemispheric asymmetries of selective attention and that the ear hemisphere that usually processes a class of stimuli has greater difficulty filtering out those stimuli than does the nonspecialized hemisphere.