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Biomedical subjects

S Wiegersma

Publications and source records attributed to S Wiegersma.

12 recordsLinked to original sources
PubMed1991

Asymmetry in a verbal-manual task combination: habitual vs controlled verbal production.

Interference between verbal production and left- and right-hand tapping was studied in male right-handed subjects in two experiments. The hypothesis was studied that controlled rather than automatic verbal production causes the interference with right-hand performance. Experiment 1 compared the repeated production of one verbal number response with the production of a random sequence of numbers. Experiment 2 studied one additional condition: counting from one to 20. The results showed that repetition and counting do not selectively interfere with right-hand tapping, while the randomization of numbers does. These results support the controlled-processing hypothesis of interference with right-hand performance.

Adult↗
PubMed1991

Subjective ordering and working memory in alcoholic Korsakoff patients.

Frontal-lobe dysfunction of alcoholic Korsakoff patients was studied by presenting four tasks requiring short-term retention, as well as different degrees and types of control. Digit span forward was considered a measure of passive short-term retention; missing scan measures memory search and comparison, in addition to retention; and two subjective ordering tasks measure active generation of responses in addition to the processes in the other two tasks. The results showed no evidence of reduced performance for any of these tasks, when compared with performance of control subjects. The hypothesis that Korsakoff patients have a frontal-lobe dysfunction in addition to their amnesia needs some qualification because of these results: Frontal-lobe function specific to the ordering of verbal responses seems to be intact in Korsakoff patients.

Adult↗
PubMed1990

Subjective ordering, short-term memory, and the frontal lobes.

Four tasks relying on short-term retention, i.e. digit span, missing scan, randomization span, and pointing span were presented to patients with frontal-lobe lesions and normal controls. Digit span was considered a measure of passive short-term memory, the other three tasks additionally reflect comparing processes, and two of these, the randomization and pointing spans, also measure active ordering by the subject. The results confirmed Petrides and Milner's (Neuropsychologia 20, 249-262, 1982) hypothesis that frontal-lobe patients are typically deficient in subject-ordered tasks. It is also suggested that they are deficient in a spontaneous generation, rather than comparison component of subjective ordering.

Brain Neoplasms↗
PubMed1989

Some variables in the blue (red) phenomenon.

The relation between spontaneous color choices and ratings of the prototypicality, conspicuousness, and pleasantness of colors was studied in a sample of Dutch college students. Pleasantness, not prototypicality or conspicuousness, determined the four most frequent spontaneous choices--red, blue, green, and purple. Subjects considered blue the most pleasant of the 12 colors studied, which suggests a pleasantness explanation for the "blue phenomenon" found in some countries. The predominance of red as a spontaneous choice replicated the results of previous studies in the Netherlands. Red also was rated highest in prototypicality but was not rated higher by red choosers than by choosers of other colors, so that a simple prototypicality explanation was rejected. Further analysis showed that the predominance of red as the spontaneous choice of Dutch subjects can be explained by an interaction between prototypicality and pleasantness: Subjects tended to choose red when they rated it highly on both variables.

Adult↗
PubMed1988

Encoding of frequency of occurrence by aphasia patients: attentional or linguistic deficit?

Frequency-encoding performance of aphasic patients and control subjects was studied in order to test Grober's (1984) hypothesis that aphasic patients are not deficient in the encoding of frequency of events. Experiment 1 compared patients and controls on four types of list: spoken words, visual words, images of objects, and abstract figures. Experiment 2 varied semantic and phonological similarity among the words in one list. Both experiments found differences between the groups, and differences between conditions. The deterioration in patients tended to be greater for linguistic than for nonlinguistic material (experiment 1), and was strongly enhanced by semantic similarity (experiment 2). Results are better explained by a linguistic deficit than by an attentional capacity account of aphasia.

Adult↗
PubMed1987

The effects of visual conspicuousness and the concept of randomness on the recognition of randomness in sequences.

In a number of studies, tendencies toward nonrepetition in judgments of randomness of visually presented sequences of events have been attributed to a biased concept of randomness. The present study proposed that such bias is due to "bottom-up" visual processes rather than a concept of randomness. Experiment 1 showed that judgments of randomness were less biased when repetitions were made less conspicuous by increasing the distance between adjacent items. Experiment 2 produced comparable results for increasing dissimilarity of categorically identical items. A third experiment showed that the bias in the judgment task was not related to a more direct measure of knowledge of random processes, the assignment of probabilities of repetition to imagined random sequences. The results supported the view that judgments of randomness are determined to a high degree by the conspicuousness of repetitions and are independent of the concept of randomness.

Attention↗
PubMed1986

Errors of free recall in senile dementia.

Errors made in the free recall of nouns by patients with senile dementia were classified as to their paradigmatic, phonological, or syntagmatic relationships with presented words. Dementia patients at four levels of dementia severity made relatively more paradigmatic errors than normals. Syntagmatic errors only occurred for greater severity. Such errors show the relative preservation in dementia of semantic knowledge about words as well as the decreased paradigmatic and syntagmatic discriminability of words.

Aged↗
PubMedDate not supplied

Subjective ordering, working memory, and aging.

Cognitive decline in aging was studied by presenting four tasks involving short-term memory to young and old adults: digit span forward, missing scan, randomization span, and randomization span visual. Results showed that performance declined significantly with age in the latter two tasks, which require subjective ordering of a sequence of responses, and not in the first two tasks, which involve reproduction of a presented sequence and searching and comparison processes.

Adolescent↗