Context dependent changes in the reinforcing strength of schedule-induced drinking.

Previous experiments show that the opportunity to engage in schedule-induced responding is reinforcing. In this experiment, the reinforcing strength of schedule-induced drinking was measured. Four rats were trained on a concurrent-chain schedule. The two terminal links provided food pellets on identical fixed-time schedules. In addition, one terminal link also provided the opportunity to press a button that operated a water dipper. In this link, the rats showed polydipsic drinking. Button-pressing rate for polydipsic drinking was a bitonic function of pellet rate, and it was possible to describe the relationship with a slightly modified version of the matching equation for primary reinforcement. This equation also closely fit the data from other studies. Initial-link response rates, however, did not appear to be influenced by the availability of water in the terminal links. Control conditions suggested that the reinforcing strength of polydipsia was strongly bound to the context provided by periodic food reinforcement.     

Representation of inflected nouns in the internal lexicon

The lexical representation of Serbo-Croatian nouns was investigated in a lexical decision task. Because Serbo-Croatian nouns are declined, a noun may appear in one of several grammatical cases distinguished by the inflectional morpheme affixed to the base form. The grammatical cases occur with different frequencies, although some are visually and phonetically identical. When the frequencies of identical forms are compounded, the ordering of frequencies is not the same for masculine and feminine genders. These two genders are distinguished further by the fact that the base form for masculine nouns is an actual grammatical case, the nominative singular, whereas the base form for feminine nouns is an abstraction in that it cannot stand alone as an independent word. Exploiting these characteristics of the Serbo-Croatian language, we contrasted three views of how a noun is represented: (1) the independent-entries hypothesis, which assumes an independent representation for each grammatical case, reflecting its frequency of occurrence; (2) the derivational hypothesis, which assumes that only the base morpheme is stored, with the individual cases derived from separately stored inflectional morphemes and rules for combination; and (3) the satellite-entries hypothesis, which assumes that all cases are individually represented, with the nominative singular functioning as the nucleus and the embodiment of the noun’s frequency and around which the other cases cluster uniformly. The evidence strongly favors the satellite-entries hypothesis.     

Visual and auditory selective attention and reflection-impulsivity in normal and learning-disabled boys at two age levels

Selective attention to visual and auditory stimuli and reflection-impulsivity were studied in normal and learning-disabled 8- and 12-year-old boys. Multivariate analyses, followed by univariate and paired-comparison tests, indicated that the normal children increased in selective attention efficiency with age to both visual and auditory stimuli. Learning-disabled children increased in selective attention efficiency with age to auditory, but not to visual, stimuli. Both groups increased with age in reflection as measured by Kagan's Matching Familiar Figures Test (MFF). The 8-year-old learning-disabled children were more impulsive than the 8-year-old normals on MFF error scores, but not on MFF latency scores. No difference occurred between the 12-year-old learning-disabled and normal children on either MFF error or MFF latency scores. Correlations between the selective attention scores and MFF error and latency scores were not significant.This research was supported in part by BEH grant G007507227. The authors are indebted to Eleanor McCandless for her assistance in securing the learning-disabled subjects and to James McLeskey and Michael Popkin for their assistance in collecting and analyzing data.     

Scaling clinical judgments of symptom pathology by means of the psychophysiological method of magnitude estimation

Summing scores across heterogeneous symptom items without consideration of their differing psychopathological significance has been criticized as producing an inadequate picture of an individual's clinical status. The purpose of this study was to derive symptom item weights representing clinically judged seriousness of each symptom through the application of Stevens's psychophysical method of magnitude estimation. A nationwide sample of 129 clinicians rated the pathological significance of 221 symptom items in a design such that every rater rated 121 items, 21 of which were rated by all raters and 100 of which were rated only by the A or B subgroup to which each rater was randomly assigned. Each item was rated as to the seriousness of the pathology it would represent if manifested by either a boy child, girl child, boy adolescent, or girl adolescent, with one-fourth of the raters assigned to each condition. The results of 211 two-way analyses of variance revealed that age and age and sex in interaction, but not sex alone, significantly influenced the clinical ratings. The resulting magnitude estimation ratings of symptom pathology ranged from 1.0 to 9.9. They were demonstrated to have satisfactory reliability and convergent validity and to have the psychophysical characteristics of a prothetic continuum.A preliminary version of this paper was presented at the 85th Annual Convention of the American Psychological Association, San Francisco, August 1977. The research was supported by HEW grant MH24886. The authors wish to express appreciation to Walter W. Wengel for his work in developing the median quotient ratings used in the study, to Terrance Auger for making available unpublished raw data, and to Merton S. Krause for helpful suggestions regarding the interpretation of results.     

Accessibility of the voicing distinction for learning phonological rules

In three experiments a series of nonsense syllables ending in consonants was presented to adult subjects who had to discover or learn a rule classifying the syllables into two groups. The rule was based either on the voicing of the final consonants or on an arbitrary division of them. Subjects performed better with the voicing than with the arbitrary rule only when there was a straightforward relationship between the voicing rule and the plural formation rule in English or, more generally, when voicing assimilation with an added consonant was involved and attention was focused on the sound and articulation of the syllables. We conclude that the voicing distinction is not ordinarily accessible and that individuals easily learn and use phonological rules involving voicing assimilation because of articulatory constraints on the production of consonant clusters.     

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.     

Auditory processing of brain-damaged adults under competitive listening conditions

Right CVAs, mild left CVAs, and non-brain-damaged adults received the Token Test under three conditions: quiet, white noise, and speech babble. Left CVAs performed most poorly of all groups in all conditions experiencing difficulty with subtests III, IV, and V. Right CVAs were inferior to controls on each of these three subtests in the speech babble condition only. Thus, right CVA difficulty with both memory and syntactic tasks was demonstrated in speech babble. These results are explained by the hypothesis that both hemispheres are necessary to process auditory information under complex listening conditions. Total brain capacity of right CVA patients may be overloaded if either memory load or linguistic complexity is increased in the presence of certain types of listening competition.     

The communication disorder in dialysis dementia: A case report

The communication disorder in dialysis dementia is an integral feature of the syndrome. This report describes the communication disorder in a 67-year-old man over a period of 4 months from his admission to the hospital to his death. In the early stage of the syndrome, the most prominent feature was a speech problem, the characteristics of which may vary among cases. In the middle stage, it was difficult to distinguish among aphemia, aphasia, or a combination of dysarthria and confusional state. The severity of the problems in these stages was temporally related to the dialysis treatments. The final stage was characterized by constant mutism and was unrelated to the dialysis treatments. Death occurred 10 months after the communication problems emerged. Communication studies of dialysis dementia patients may offer a systematic method to monitor the course of the syndrome, its response to therapeutic trials, and a clinical model for the study of communication disorders in general.