Voice onset time in aphasia: Thai II. Production

The aim of this study was to investigate voice onset time (VOT) production in homorganic word-initial stops in Thai in order to explore the nature of speech production deficits across clinical varieties of aphasia. Thai exhibits a three-category distinction in bilabial (/b,p,ph/) and alveolar (/d,t,t,h/) stops, and a two-category distinction in velar (/k,kh/) stops. Subjects included three Broca asphasics, one transcortical motor asphasic, two global asphasics, one conduction aphasic, one Wernicke aphasic, one nonaphasic dysarthric patient, one right-brain-damaged patient, and five normal controls. Test stimuli consisted of eight monosyllabic real words. The results of VOT measurements indicated that Broca and global asphasics exhibited a more severe production disorder than Wernicke, conduction, or transcortical motor asphasics. The right-brain-damaged patient showed no impairment in VOT production. Comparisons are drawn to earlier studies of VOT production in aphasia in two-category languages. Issues concerning the underlying basis of the production deficit for nonfluent aphasics, fluent aphasics, and nonaphasic dysarthrics as well as the relation between perception and production of VOT are discussed.     

Models of central capacity and concurrency

According to single channel theory, the ability of humans to perform concurrent mental operations is limited by the capacity of a central mechanism. The theory was developed by analogy with early computers which had a single central processing unit and required sequential processing. These limitations are not likely to be properties of the mind. But now computers have begun to employ extensive concurrent processing, because of the decreasing cost of the necessary hardware. In this review we will try to bring the computer analogy up to date. Theoretical issues important for concurrent systems may be of interest to psychologists and have applications to such problems as the speed-accuracy trade-off. Several hypotheses about the way signals gain access to the central mechanism are reviewed. Recent variations of the single channel theory are discussed, including the hypotheses that more than one process can use the central mechanism at a time, and that some processes do not use the central mechanism and can be executed concurrently with those that do. In addition, relevant concepts from scheduling theory and operating systems theory are introduced and difficulties encountered by concurrent systems, namely complexity, deadlocks, and thrashing, are discussed.     

When is an easy task difficult and vice versa? A reply to lane

Lane has argued that kantowitz and Knight incorrectly predicted an interaction between primary and secondary task difficulty for the variable-allocation model of attention. It is shown that such an interaction is indeed obtained if task-performance difficulty is defined in terms of capacity and only reasonable transformations of data are permitted. This interaction holds for any set of monotonic resource operating characteristics.     

Further analysis of stuttering as a phonetic transition defect

This article presents a further analysis of stuttering as a phonetic transition defect. Three types of phonetic transitions are identified. Two of these occur within words and represent sites where stutterings are readily detectable. The third transition involves movement from the end of one word to the beginning of the next. Spectrographic evidence is provided to show that stuttering also occurs at points of transition of this type. The same data are interpreted relative to their implications for stuttering theory, research, and therapy.     

Atttudes and behavior: Implications of attitudes toward behavioral alternatives

The relationship between attitudes and behavior was considered. An attitudinal model of behavioral alternatives was presented and its applied and theoretical implications explicated. Three investigations were reported that tested the initial viability of the approach. Support for the model was observed in all three investigations.     

Some theory and results for metrics for bounded response scales

In an earlier note, a new metric for bounded response scales (MBR) was introduced which resembles the city-block metric but is bounded above. It was suggested the MBR may be more appropriate than minkowski metrics for data obtained with bounded response scales. In this article, some formal properties of the MBR are investigated and it is shown that it is indeed a metric. Empirical predictions are then derived from the MBR and contrasted with those of a “monotonicity hypothesis,” which holds that dissimilarity judgements tend to be biased towards overestimation of larger distances, and with the predictions of the minkowski metrics, which imply additivity of collinear segments. Some empirical results are presented which contradict the monotonicity hypothesis and the minkowski metrics, and favor the MBR. Finally, the logic used to motivate the MBR is invoked to define a subadditive concatenation for bounded norms in the one-dimensional case, which may be useful in psychophysical work where the upper bounds are often real, rather than due to the response scale. This concatenation predicts understimation for doubling and overestimation for halving and middling tasks.     

A study of language functioning in Alzheimer patients

Language functioning in Alzheimer's disease is reviewed and the performance of 25 Alzheimer patients on a standard battery is reported. All these hospitalized patients were aphasic to some degree. As a group, they differed from normals on all language variables, and from stroke patients in terms of higher fluency and lower comprehension. Spontaneous speech showed high incidence of circumlocutions and semantic jargon, but no phonemic paraphasias or target approximations. Syllabic perseverations, shouting, inappropriate laughter, and mutism were late-appearing features. Transcortical Sensory, and Wernicke's aphasias were frequent, but Broca's and Transcortical Motor aphasias notably absent. Extent of language impairment correlated with current length of hospitalization but not age. Reading, writing, and performance scores except praxis, were lower than oral language scores. Findings were discussed in relation to previous results, methodology, and language organization in the brain.     

Effects of expectancies of different reward magnitudes in transfer from noncontingent pairings to instrumental performance

In two experiments, rats received noncontingent pairings of two stimuli with food reward, one paired with small reward and the other with large reward, and received bar press training with large reward or with small reward. When the noncontingent stimuli (NS) were presented for test during subsequent rewarded bar pressing and during early extinction of bar pressing, responding for each group was faster in the presence of the NS which was paired with the same reward magnitude that group received in bar press training than to the NS which had been paired with a different reward magnitude. As extinction progressed, all groups responded more slowly in the presence of the NS which had been paired with the large reward than in the presence of the NS which had been paired with small reward. These results were interpreted as indicating that responding in the presence of an NS depends on: (i) whether the reward expectancy elicited by the NS has been conditioned to the instrumental response, and (ii) the relationship between the reward expected in the presence of the NS and that received in test.     

Effect of shifts in body weight on rats' straight alley performance as a function of reward magnitude

The performance of rats trained in a straight alley for 55 trials under 75% body weight and then shifted to 90% body weight was compared to that of rats trained only under 90% body weight. When training was with a small reward the speed of the shifted group decreased to the level of the 90% small reward control groups, but when training was with a large reward the speed of the shifted group dropped below the level of the 90% large reward control group. Thus, the effects on performance of shifting deprivation level following extended training depend on the reward magnitude employed.     

Situation-specific variables as determinants of perceived environmental aesthetic quality and perceived crowdedness

It was hypothesized that relevant situation-specific variables may act along with objective physical conditions to determine environmental perception, and that the exclusive use of the physical level of an environmental stimulus to predict behavior may, therefore, be inadequate. A 2 × 4 between-subjects design was employed in which an attitudinally similar or dissimilar confederate interacted with a subject at one of four distances. As hypothesized, subjects who interacted with a similar confederate judged the environment to be of higher aesthetic quality, perceived themselves to be less crowded, and felt affectively more positive than subjects who interacted with a dissimilar other. The results were also interpreted as supporting the utility of the Byrne-Clore (1970) reinforcementaffect model of evaluative responses as a means of predicting environmental perception and the behavioral response to environmental stimuli.