Effects of sentential stress and word class upon comprehension in Broca's aphasics

The roles which word class (open/closed) and sentential stress play in the sentence comprehension processes of both agrammatic (Broca's) aphasics and normal listeners were examined with a word monitoring task. Overall, normal listeners responded more quickly to stressed than to unstressed items, but showed no effect of word class. Aphasics also responded more quickly to stressed than to unstressed materials, but, unlike the normals, responded faster to open than to closed class words regardless of their stress. The results are interpreted as support for the theory that Broca's aphasics lack the functional underlying open/closed class word distinction used in word recognition by normal listeners.     

Right-hemisphere language: Familial and nonfamilial sinistrals,cognitive deficits and writing hand position in sinistrals,and concrete-abstract,imageable-nonimageable dimensions in word recognition. A review of interrelated issues

While left-hemisphere language dominance is more general than dextrality, and reversed dominance is less frequent than sinistrality, there are disputes in both the clinical and the experimental literature on a number of related issues which pertain to a possible language contribution from the minor hemisphere. These issues include the nature and extent of bilaterality in sinistrals, whether this is more pronounced in the strongly or weakly sinistral, and in those with or without other sinistral close relatives, whether sinistrality is largely or at all a consequence of birth stress, whether sinistrals differ from dextrals in visuospatial or even verbal skills, Levy's (1978) hypothesis that a knowledge of the hand position employed in writing (hooked or noninverted) may accurately predict language lateralization in sinistrals, and the possible extent of a minor hemisphere contribution to the recognition of high frequency, concrete, or imageable nouns. Findings relating to the above issues are reviewed, and it is concluded that much of the current confusion stems from poor control of subject factors such as sex, strength and family history of handedness, and nature of stimuli and their mode of presentation.     

Cognitive task effects on hemispheric blood flow in humans: Evidence for individual differences in hemispheric activation

Evidence from two indirect measures of hemispheric activity, EEG α and conjugate lateral eye movements, has pointed to the existence of individual differences in hemispheric activation. Results from a more direct indicator of hemispheric activity, regional cerebral blood flow as measured by the ¹³³Xe inhalation method, show that such individual differences can be detected in the distribution of blood in the two hemispheres and that the amount of increase in blood flow in the right relative to the left hemisphere is correlated with performance on a spatial task. These results corroborate and extend the findings from the EEG and eye movement studies and suggest that the dimension of individual differences in hemispheric activation may exert significant influence on cognitive performance and on problem-solving strategies.     

The effect of set size on hemifield asymmetries in letter recognition

Single letters were presented tachistoscopically in the left or right hemifield to right-handed observers. Superior recognition of letters on the right was found for letters chosen from subsets containing four items, but no differences were found when any letter, or any symmetrical letter, could appear. In a second experiment, the right hemifield advantage was found under conditions requiring the subject to determine the subset only when the subset chosen was appropriate. Results were discussed in terms of the adequacy of language-based explanations of hemifield asymmetries in letter recognition.     

Verbal and nonverbal recognition memory in aphasic and nonaphasic stroke patients

The ability to retain lists of verbal and nonverbalizable items across recurrent recognition tasks was tested in three groups: (1) stroke patients with a left-brain lesion and aphasia, (2) stroke patients with a right-brain lesion and left hemiplegia, and (3) nonneurologically impaired outpatients. As determined with signal detection measures, aphasics were deficient in discriminating words that were to be remembered from those that were not; their recognition of nonverbal visual (geometric art) or auditory (bird calls) patterns, however, was unimpaired. Left hemiplegics showed the opposite pattern. After a long-term interval (<10 min), correct recognition of words was diminished in all groups whereas recognition of visual patterns increased. Both groups of stroke patients adopted material-specific decision criteria which in part accounted for the dissociation of verbal and nonverbal recognition memory by laterality of lesion. Item analysis indicated that aphasics' verbal memory difficulties were affected by acoustic-semantic confusion of list words.     

Word-finding as a function of stimulus context: Children compared with aphasic adults

A study of object naming in 202 children, aged 5–11 years, demonstrated that varying the stimulus context affected the level of response accuracy. From age 6 to 10, completing a sentence with a noun (auditory) yielded the lowest error scores, naming objects upon hearing a definition (also auditory) produced most errors, while responding with names to pictured objects was of intermediate difficulty. This is the same order of object naming difficulty found in adult aphasic patients. Children older than 10 do not appear to be affected by stimulus context in their object naming. Results are discussed in terms of the relative syntactic difficulty of the two auditory conditions, the unexpected sex differences, and the “aphaseoid” naming errors of children.     

Right-hemisphere speech representation and comprehension of syntax after left cerebral injury

Comprehension of language and visuo-spatial abilities were studied in 12 surgical patients with left cerebral lesions and right-hemisphere speech representation verified by sodium amobarbital tests. When left-hemisphere symptoms preceded the acquisition of speech, impaired understanding of syntactically complex sentences was associated with an early, but not late, onset of convulsive seizures. Other behavioral measures did not show a similar effect of age at seizure onset. Sparing or loss of comprehension could not be related to any aspects of the neurological histories in cases with right-hemisphere speech acquired before the onset of left-hemisphere symptoms. Factors which may have influenced the development of right-hemisphere language comprehension are discussed.     

Environmental dispositions and the evaluation of architectural interiors

The Environmental Response Inventory (ERI) was developed, in part, to assess dispositions toward everyday physical environments and to aid in explaining variance in response to settings. The eight ERI scales were examined and resultant hypotheses were tested in a design involving evaluative ratings of 10 everyday public building interiors briefly presented in sequences of color slides to 118 participants. Settings were arranged in three levels of generality. Results support the ERI as a promising tool. Biographical items also correlate with ratings. Environment evaluation is discussed as a complex phenomenon, in which rater differences play a significant part.     

Visual processing of multielement arrays and selective backward masking

In the first of two selective masking experiments, 7-letter rows were followed at several ISIs by a mask or no-mask and a bar-marker partial report cue. The results suggest that the arrays were processed ends-first and then, in general, from both ends towards the middle. In the second experiment, bar-marker partial report cues were presented at the onset or offset of 6-letter/1-digit or 7-letter rows. The subjects could not anticipate the category of the to-be-reported item with the alphanumeric displays. With a delayed cue, selective masking was obtained with both mixed category and pure letter arrays, but with simultaneous cuing, masking was always distributed across all serial positions. The results suggest that the subjects: (a) abstracted some information about category from the mixed arrays during an initial parallel stage of processing, (b) selectively attended to mainly the cued item with simultaneous probes with homeogeneous and mixed category displays, and (c) employed an ends-first processing strategy with both types of arrays when the bar-marker partial report cue was delayed.     

The availability explanation of excessive plausibility assessments

The assessment of hypotheses in hypothesis generation involves a comparison between those hypotheses that have been generated (specified) and those that are not generated (unspecified). Experiment 1 was an investigation of an “availability explanation” for subjects' overconfidence in the probability of specified hypotheses. The conjecture is that subjects have difficulty retrieving unspecified hypotheses from memory. Therefore, the underpopulated set of unspecified hypotheses is assessed as less probable then it actually is and the specified set is assessed as more probable. Two manipulations to increase the availability of unspecified hypotheses were investigated. One involved explicitly requesting subjects to populate the unspecified set; the other was a computer presentation of candidate unspecified hypotheses. Results of experiment 1 were that assessment overconfidence for both experimental groups was reduced. The results support the conjecture that the availability heuristic is at least partially responsible for subjects' overconfidence. The main result of experiment 2 was that the overconfidence bias persisted with different assessment methods for both subject-generated and experimenter-supplied hypotheses.