Case study of a Thai conduction aphasic

A case study of a 55-year-old nonfamilial left-handed monolingual Thai patient with clinical and pathoanatomic evidence of major infarction in the left temporoparietal region is presented. He was studied at 9 years poststroke with a Thai adaptation of the Boston Diagnostic Aphasia Exam and supplementary tests. His language characteristics included fluent spontaneous speech, near-normal auditory language comprehension, and poor repetition, leading to a diagnosis of conduction aphasia. In regard to this aphasic syndrome, issues concerning classification, neuroanatomic correlates, and underlying neuropsychological mechanisms are addressed. The nature of his grammatical disturbance is examined critically in light of the notion of “information load.”     

Prosodic disturbance in aphasia: Vowel length in Thai

The aim of this study is to determine to what extent a phonologically contrastive function of the prosodic feature of length is resistant to impairment in aphasia. The language chosen for investigation is Thai, a language which contrasts short and long vowels. Subjects included two Broca aphasics, one transcortical motor aphasic, one Wernicke aphasic, one conduction aphasic, one nonaphasic right-brain-damaged patient, one nonaphasic cerebellar dysarthric patient, and five normal controls. The subjects read a list of words containing short and long vowels. Vowel durations were measured from spectrograms. The results showed that the timing of vowel duration for signaling the contrast between short and long vowels remains relatively intact in nonfluent as well as fluent aphasic patients. These data are brought to bear on issues concerning the specialization of the left hemisphere for temporal processing, the contribution of the right hemisphere to the processing of nonaffective components of prosody, the nature of prosodic disturbance in Broca's aphasia and cerebellar dysarthria, and the separate disruption of prosodic features.     

Confrontation naming impairment in dementia

In tone languages pitch variations (tones) serve to distinguish the lexical meanings of words. This study was conducted to examine the extent and nature of impairment in the perception of tones by aphasic patients who were monolingual speakers of Thai, a tone language which has five contrastive tones (mid, low, falling, high, rising). Six subjects participated in the study: two Broca aphasics, one transcortical motor aphasic, one conduction aphasic, one right brain-damaged nonaphasic, and one normal control. Three sets of stimuli (two real-speech, one synthetic-speech) were presented for identification, each set containing five Thai words minimally distinguished by tone. Results of the perception tests indicated that the performance of all four left brain-damaged aphasics differed significantly from that of the normal control, while the performance of the right brain-damaged nonaphasic did not. The normal performance of the right brain-damaged nonaphasic patient on this tone identification task suggests that deficits in the perception of tone exhibited by left brain-damaged patients can be attributed specifically to pathology in the language dominant hemisphere rather than to a general brain-damage effect. No difference in performance among the left brain-damaged patients could be attributed to a specific type of aphasic syndrome. The pattern of tonal confusions of the aphasics in comparison to that of normals suggests that their deficit is primarily quantitative rather than qualitative. Although two (mid, low) of the five tones accounted for a large percentage of the aphasics' errors, no uniform rank order of tones in terms of identifiability could be established across aphasic subjects, which suggests that their deficit is general to all five tones rather than selective to individual tones.     

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.     

Rate reduction strategies used by stutterers and nonstutterers during high- and low-pitched speech

Groups of child and adult normal speakers and stutterers were tested in an habitual condition and in conditions where they were instructed to read aloud at pitches both higher than and lower than normal. Objective measures were made of subjects' fluent reading rate, and vowel and pause durations across conditions. Disfluencies were also counted. Findings revealed that all four subject groups reduced their frequency of disfluency from the habitual to both experimental conditions. These decrements in disfluency were attended by significant reductions in fluent reading rate. Spectrographic analyses revealed that most subjects, regardless of age and speaker characteristic, affected their rate reduction by extending both vowel and pause durations. These results are compatible with those obtained in recent studies and are discussed.     

Voice onset time in aphasia: Thai. I. Perception

This study investigated left brain-damaged aphasic and right brain-damaged non-aphasic patients' ability to label synthetic speech continua differing in voice onset time (VOT) at three places of articulation. The language chosen for investigation was Thai, which exhibits 3 contrasting labial and apical stop categories (voiced, voiceless unaspirated, voiceless aspirated) and 2 contrasting velar stop categories (voiceless unaspirated, voiceless aspirated). Results of the labelling task indicated an impairment in VOT perception at all three places of articulation across clinical types of aphasia. Normal performance by the right brain-damaged patient indicated that deficits in VOT perception can be attributed to pathology specific to the language-dominant hemisphere. No relation was found between the aphasic patient's level of auditory language comprehension and his performance on the VOT perception task. It is suggested that the aphasics' impairment reflects a deficit in phonological processing at the linguistic level.     

The effects of prior task experience in the modeling situation

An investigation was made into the effects of observers' previous experience with the experimental task on acquisition and subsequent performance of modeled task behavior. The task was socially neutral and the subjects were second grade boys and girls. Recall of modeled actions increased with prior experience, indicating greater acquisition. This finding supports Bandura's (1973) assertion that task familiarity may enhance attentiveness to the model. Contrary to previous research, performance of imitation did not decrease with experience. The present performance results are possibly due to the ambiguity of the preexperience and novelty of the experimental task.     

Development of mental rotation: A speed-accuracy study

Pairs of letters and numbers were shown to 11-, 14-, and 19-year-olds. One stimulus in a pair was presented upright. The second, which was either identical to the first or a mirror image of it, was rotated 0 to 150° from the vertical. Individuals judged if the stimuli in a pair would be identical or mirror images if presented at the same orientation. They did so under instructions that emphasized accurate responses, fast responses, or fast and accurate responses. Typically, responses were (1) most accurate and slowest when accuracy was emphasized, and (2) least accurate but fastest when speed was emphasized. The data from the three instructional conditions were used to derive measures of response times in which accuracy of response was equated for the three age groups. At 95% accuracy 14- and 19-year-olds mentally rotated stimuli at the same rate, which was faster than 11-year-olds' rate. At 100% accuracy, 19-year-olds mentally rotated stimuli more rapidly than both 11- and 14-year-olds, who did not differ from one another.     

Resistance to satiation: Reinforcing effects of food and eating under satiation

It has been shown previously that rats which have learned a response when hungry will continue to make that response when tested satiated, a phenomenon labeled resistance to satiation. Here we showed that rats which were previously trained hungry will learn a new response for the opportunity to consume pellets in a new situation when tested satiated. In four experiments various groups received each of the components of the training given when rats learn an instrumental response when hungry. Rats were placed in the goalbox of a straight alley and given food pellets when hungry or were hungry only in their home cages prior to running a straight alley in the satiated test in Experiment 1. In Experiments 2, 3, and 4 learning of a differential conditioning problem for pellets in S+ (nonreward in S?) was measured in the satiated test. Groups given pellets in their home cages when hungry with or without alley exposure learned to run more rapidly in S+ than in S? in the satiated test phase. The tendency to eat pellets in the apparatus and the reinforcing effect of eating the pellets was larger for rats which ate the pellets when hungry in their home cage than for rats which ate the pellets when satiated in their home cage. Being hungry in the home cage with no pellets was not sufficient to produce eating or running for pellets in the satiated test, indicating that any inherent reinforcing effect of the pellets is not sufficient to produce eating or running, and that incomplete satiation cannot account for the learning. These data indicate that a reinforcing effect of eating pellets under satiation is an important determiner of resistance to satiation.     

A Plumber's friend in need is a Plumber's friend indeed

In response to the critique of Gaes, Quigley-Fernandez, and Tedeschi (Journal of Research in Personality, 1978, 12, 189–192) it was acknowledged that the cell Ns were incorrect as originally reported, and the weakness of a postexperimental division of subjects was reaffirmed. Emphasis was placed on the comparability of a simple rating scale and an elaborate bogus pipeline in measuring attraction. The need for determining the way in which the bogus pipeline functions prior to its uncritical adoption in any given experimental situation was stressed as a point of agreement.     

The bias of an estimate of coupled slack in stochastic PERT networks

An earlier paper presented a method for using response times to construct a PERT network representing the mental activities in a task. A key role in this method is played by parameters called coupled slacks. The magnitudes of the coupled slacks are used to test the validity of a PERT model and to deduce aspects of the structure of the network. In a stochastic PERT network, the usual estimate of coupled slack based on the mean completion times can be biased. Distribution-free upper and lower bounds are derived for the bias, and it is shown that the bias approaches zero as the probability of relatively long prolongations increases. It is also shown that the expected value of the estimate of coupled slack between two activities is negative only if the two activities are in a Wheatstone bridge. Finally, an estimate of the increase in completion time due to prolonging an activity, given that the prolongation did in fact increase the completion time, is derived.     

Shock preexposure and the reduced effectiveness of shock

In three experiments experience with shock was shown to reduce the effectiveness of shock as a reinforcer or motivator. In Experiment 1 rats were given signaled shock in a box separate from the runway where they were subsequently punished. These rats were less suppressed by shock punishment than rats that had no previous shock experience. In Experiment 2 preshocked rats were less suppressed by punishment and were slower to learn an escape-avoidance response than nonpreshocked rats, whether the preshock was signaled or unsignaled. In Experiment 3 as number of CS-shock pairings increased, fear of the CS decreased as did fear of the context. These results suggest that some central adaptation process produced by experience with shock reduces the effectiveness of shock as a reinforcer whenever shock is used repeatedly. This is independent of other effects, such as context blocking, that can affect responding after shock preexposure.     

Clogs in the bogus pipeline: Demand characteristics and social desirability

Jones and Sigall (1971) have advocated the use of a pseudophysiological monitoring device (the bogus pipeline) as a procedure to measure the “true” feelings of experimental subjects. A comparison of the bogus pipeline and a paper-and-pencil scale as measures of attraction indicated that the monitoring device is affected by experimenter demands among high social desirability (SD) subjects (p < .03) while the simple rating scale is not. Attraction to a stranger was determined solely by attitude similarity for high SD subjects using the paper-and-pencil measure and for low SD subjects in both measurement conditions. Use of the bogus pipeline in the typical attraction experiment thus would seem to be contraindicated. These results were discussed with respect to Ostrom's (1973) criteria of relative sensitivity and functional comparability of measurement techniques.