Visual perseveration in normal and mentally retarded children

Visual perseveration was investigated within mentally retarded and second, fifth, and eighth grade normal children (Ns = 12 each group). Subjects matched an auditorially presented click to the onset and offset of visually presented stimuli. Time differences between visual stimulus offset and the point at which subjects reported simultaneity of the click and visual stimulus offset was assumed to reflect visual perseveration. Results showed: (a) no differences between the normal children as a function of age; (b) no difference between groups for stimuli of 100 msec. or longer duration; and (c) retarded subjects judged stimuli of 20 and 50 msec. to be of shorter duration than did normal subjects. This highly specific distinction between retarded and normal subjects suggests a difference in an early stage of perceptual processing.     

More learned irrelevance than perseveration errors in rule shifting in healthy subjects

The present experiments examined the extent to which two possible sources of error affect healthy subjects' performance in a rule-shift task. All 115 participants first received a discrimination learning task, in which a pair of different visual stimuli was presented on each trial, one of which had to be identified as 'correct.' Each stimulus varied in two dimensions: a task-relevant and a task-irrelevant dimension. Feedback on correctness was given after each choice. After eight successive correct choices, the nature of the task-relevant dimension changed: the post-shift learning phase. Two types of error can occur in this phase: continued responding to the former relevant, but now irrelevant, dimension, a perseverative error, and non-responding to the former irrelevant, but now relevant, dimension, an error due to learned irrelevance. Different groups received a post-shift task in which none, one, or both of these two types of error could affect performance. The number of incorrect choices in the post-shift phase was significantly affected by learned-irrelevance errors but not by perseverative errors. An associative-learning model incorporating feedback-induced changes in both associative strength and saliency of the elements comprising the stimuli can explain these results.     

Covariates of production and perseveration on tests of phonemic, semantic and alternating fluency in normal aging

Standard measures of phonemic and semantic fluency, as well as fluency measures that impose additional demands upon set-switching were administered to younger and older adults. No age effect was found for total output on semantic fluency, while older participants generated significantly more responses relative to their younger counterparts on the phonemic measure. However, older adults made significantly more perseverative errors on both these measures. For tests of alternating fluency, only where participants were required to switch between two semantic dimensions, was an age deficit observed. Although the correlation between phonemic repetitions and age remained significant when performance on the Digit Symbol Test or a measure of fluid intelligence was partialled out, age effects for semantic repetitions and semantic alternating fluency were substantially reduced. The age benefit for number of correct responses upon phonemic fluency was significantly attenuated when a measure of crystallized intelligence was entered as a control variable. The theoretical and practical implications of these results are discussed.     

Writing errors by normal subjects

Writing is a complex process requiring visual memory, attention, phonological and semantic operations, and motor performance. For that reason, it can easily be disturbed by interfering with attention, memory, by interfering subvocalization, and so on. With 16 female third-year students (23.4 +/- 0.8 yr.) from the University of Trieste, we investigated the production of errors in three experimental conditions (control, articulatory suppression, and tapping). In the articulatory suppression condition, the participants produced significantly more linguistic impairments (such as agrammatism, unrelated substitutions, sentence omissions, and semantically deviant sentences), which are similar to linguistic impairments found in aphasia. On the tapping condition there were more perseverations, deletions, and substitutions of both letters and words. These data suggest that writing is not an automatic skill. Only after many years of experience and practice of processing information (through cortical to subcortical channels) can writing be considered an automatic skill. Limited experimental conditions can disrupt the writing system of normal subjects, probably interfering with the cortical to subcortical loops, and link normality to pathology.     

Word association responses in normal adult subjects

A word association test was administered to a group of 316 undergraduate students. Word stimuli were balanced according to frequency of occurrence in written English language usage (frequent, infrequent), word length (short, long), abstraction level (low, medium, high), and grammatical class (noun, verb, adjective). Responses were analyzed according to a syntactic classification system. The factorial nature of the word list used enhances its value as a research tool.The authors wish to thank Professor Louis J. Gerstman, Department of Psychology, City College of CUNY, New York, for his assistance in preparing the statistical data in this study.     

Response perseveration in psychopathic women.

Recent attempts to validate the Psychopathy Checklist-Revised (PCL-R) as a measure of psychopathy in female offenders have been limited by a failure to examine laboratory correlates of the syndrome. We assessed 112 incarcerated women by using the PCL-R and examined their performance on a card perseveration task that has been used to demonstrate response perseveration in psychopathic men. Contrary to prediction, psychopathic women did not perseverate responding when the PCL-R was used either dimensionally or categorically. The authors discuss the implications of the results for the PCL-R and for female psychopathy more generally.     

Active versus passive proprioceptive straight-ahead pointing in normal subjects

Eighty blindfolded healthy female subjects participated in an active and a passive straight-ahead pointing task to study the estimation of the subjective sagittal middle in the presence or absence of an active haptic exploration. Subjects were to point straight-ahead with their left or right index finger starting from different right- or left-sided locations, while performing either an active movement or with the hand being passively moved by the examiner. Results showed: (i) a significant effect of the hand used only on the active straight-ahead pointing task performance; (ii) a significant effect of the starting position both on the active and passive pointing performance; (iii) a significant correlation between the two protocols only in terms of spatial bias (algebraic error) but not in terms of precision (absolute errors). These results are discussed with regards to normal and neuropsychological studies of the egocentric frame of reference.