Ear asymmetries in dichotic listening tasks which increase in difficulty

Accuracy and laterality of ear preference in repeating 2, 3 and 4 word pairs (WP) of dichotic stimuli in English and French were determined in 80 right-handed subjects (anglophone/francophone, male/female), who were tested in both their native language (L1) and nonnative language (L2). Relative performance accuracy decreased as a function of word pairs per trial (from 2 to 4) as well as language (from L1 to L2). Right-lateral preference in turn increased as a function of WP (from 2 to 4) as well as language (L1 to L2). Right-ear advantage (REA) in L2 decreased as a function of language proficiency (low to high). REA was observed in over 90% of subjects. A rationale for greater lateralization of L2 performance is offered.     

Evidence for scanning with unilateral visual presentation of letters

When letters and words are presented tachistoscopically, material from the right visual field (RVF) can be reported more accurately than that from the left visual field (LVF). The RVF superiority may reflect either left hemispheric dominance for language or directional scanning. Previous studies have deliberately focused on the cerebral asymmetry factor while "controlling" scanning and, thus, have cast some doubt on the potency of the scanning factor. Two experiments were conducted to show that scanning can induce a RVF superiority comparable to that often associated with cerebral asymmetry. The first experiment required bilingual subjects to report six English or six Hebrew letters, shown briefly in either the LVF or RVF, with order of report controlled. A RVF superiority found with English characters was matched by an equal but opposite LVF effect with Hebrew. In a second experiment, five English characters were shown briefly in either the LVF or RVF, and subjects had to identify a single character indicated by a post exposural cue. Using a spatial cue to by pass scanning, there were no field differences; with an ordinal position cue--a procedure thought to force scanning--there was a strong RVF superiority. The results show clearly that scanning can induce visual field differences.     

Optic aphasia, optic apraxia, and loss of dreaming

A 47-year-old man with a left temporo-occipital infarct in the area of the posterior cerebral artery is presented. The neuropsychological examination did not reveal aphasia or gross mental deficits. The patient presented with alexia without agraphia, color agnosia, but few visual perceptual deficits. The main impairment was in confrontation naming; he was incapable of naming objects and pictures, not from lack of recognition (excluding visual agnosia) but from lack of access to the appropriate word (optic aphasia). The patient also exhibited a deficit in the evocation of gesture from the visual presentation of an object (optic apraxia) and a difficulty in "conjuring up" visual images of objects (impaired visual imagery) and loss of dreams. The fundamental deficit of this patient is tentatively explained in terms of visuoverbal and visuogestural disconnection and a deficit of mental imagery.     

The processing of the sounds and meanings of ongoing speech by aphasic subjects

The ability of aphasic subjects to process the sounds and meanings of ongoing speech was tested. Subjects, 10 aphasic and 20 control, heard test sentences which contained one member of phonemically similar word pairs in one of three semantic contexts: congruent, neutral, and noncongruent. Immediately after hearing a sentence, subjects were to indicate which member of the word pair had been in the sentence. All subject groups had similar overall patterns of response to the different semantic contexts. The division of aphasic subjects into groups of high and low comprehenders revealed response differences. High comprehending aphasic subjects, like control subjects, demonstrated interactive processing of the sounds and meaning of speech while low comprehending aphasic subjects did not.     

Comprehending homographs in aphasia

This study assessed 13 aphasic subjects' knowledge of the multiple meanings of homographs. The results indicated that the various meanings were less available to aphasic subjects than to normal subjects. In addition, specific meanings became less available as they became less typical although the number of meanings associated with a homograph did not influence performance. Aphasia type also did not influence performance. Performance on the experimental test was significantly correlated with auditory comprehension level and picture naming ability. The results were related to recent findings on semantic organization in aphasia.     

The nature of the phonological disorder in conduction aphasia

Sequences of attempts to name pictured objects were used to examine phonological dysfunction in three diagnostic subgroups of aphasia. A prevalence of "phonologically-oriented sequences" (i.e., those sequences that contained only attempts with a phonological resemblance to the target word) was found to be a diagnostic criterion for conduction aphasia. When compared to a group of Broca's (n = 7) and Wernicke's (n = 5) aphasics, all the conduction aphasics (n = 6) produced proportionately more of such phonologically-oriented sequences on a picture naming test. An examination of the phonologically-oriented sequences produced by the conduction aphasics indicates that speech production in conduction aphasia involves dysfunction at an early stage of sound-encoding. The theoretical implications of this view are discussed.     

The recurrence ratio

The rationale for and method of computing a measure of stuttering recurrence that is superior to methods previously developed is presented. This measure, the recurrence ratio, contrasts especially with the traditional measure of “consistency,” the percentage measure, which yields misleading values.     

Adaptive reasoning: Componential and eye movement analysis of geometric analogy performance

The present study explored individual differences in performance of a geometric analogies task. Whereas past studies employed true/false or two-alternative items, the present research included four-alternative items and studied eye movements and confidence judgements for each item performance as well as latency and error. Item difficulty proved to be a function of an interaction between the number of response alternatives and the number of elements in items, especially for subjects lower in fluid-analytic reasoning ability. Results were interpreted using two hypothesized performance strategies: constructive matching and response elimination. The less efficient of these, response elimination, seemed to be used more by lower ability subjects on more difficult items. While two previous theories resemble one or the other of these strategies, neither alone seems to capture the complexity of adaptive problem solving. It appears that a comprehensive theory should incorporate strategy shifting as a function of item difficulty and subject ability.Componential models, based in part on past research, revealed that a justification component was activated and deactivated depending upon the nature of the analogy being solved. In addition, two new components, spatial inference and spatial application, were identified as important on some items, suggesting that different geometric analogy items invoke different cognitive processing components. Thus, a comprehensive theory should also describe component activation and deactivation.