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Biomedical subjects

A Parducci

Publications and source records attributed to A Parducci.

8 recordsLinked to original sources
PubMed1990

Reducing the dependence of clinical judgment on the immediate context: effects of number of categories and type of anchors.

Two experiments explored methods for standardizing ratings of the psychopathology of clinical case histories. In both experiments, the same case histories were rated as more pathological when mostly mild rather than severe cases were presented as the immediate context. Psychometric analyses demonstrated that this type of contextual effect is a potentially important source of unreliability in clinical judgment. In Experiment 1, increasing the number of points in the rating scale from 3 to either 7 or 100 significantly reduced the effects of the immediate context. Ratings were parsimoniously modeled by Parducci's (1983) range-frequency theory. In Experiment 2, providing verbal anchors in the form of either detailed DSM descriptions for each rating category or sample case histories for the two end-categories increased the reliability of the ratings by reducing the effects of the immediate contexts; however, these reductions occurred only when the ranges of the immediate contexts had been severely restricted. According to the range-frequency analysis, verbal anchors served to equate the endpoints of the subjective range for the different contextual conditions. Comparison with previous research suggests that the anchors also reduced the effects of the sequential position in which clinical cases appear. We therefore recommend that studies of the reliability of behavioral assessment techniques take into account the effects of differences in context.

Adaptation, Psychological↗
PubMed1988

The category effect in social judgment: experimental ratings of happiness.

Three experiments demonstrated the applicability of a range-frequency analysis to social judgments. Subjects rated the happiness of either (a) schematic drawings of faces or (b) life events as expressed in short verbal descriptions. The relative frequency of these stimuli was manipulated experimentally, as was the number of rating categories. Consistent with psychophysical research, ratings became less sensitive to differences in the frequencies of contextual stimuli as the number of categories increased (the category effect). With more categories, ratings also showed less adjustment to the range of stimuli actually presented. The reduction in adjustment was greater when stimuli were presented successively and when the experimental set covered a limited range. These effects of varying the number of categories were interpreted as reflecting changes in the effective context for judgment: With more categories, the differences between the effective frequencies of contextual stimuli are reduced and new, more extreme comparison values are evoked. The implications of using coarse versus fine scales of judgment are discussed in terms of the dynamics of social judgment as well as choice of the appropriate number of categories in social research. We argue that selection of the number of rating categories should be guided by research objectives rather than by a search for "true" judgments.

Facial Expression↗
PubMed1986

The category effect with rating scales: number of categories, number of stimuli, and method of presentation.

Squares receive higher category ratings when the smaller sizes are presented more frequently than the larger sizes. This shift in the rating scale is greater when there are either fewer categories (the Category Effect) or more stimuli. Similar shifts were obtained whether the stimuli were presented successively for judgment or simultaneously. The Category Effect also occurred when subjects were not told how many categories to use until after the contextual stimuli had been presented. A simple range-frequency model describes most of the shifts in scale by variations in a single weighting parameter. However, these shifts are predicted by an elaborated model in which the number of representations of any stimulus in working memory is limited by a principle of consistent assignment of each stimulus to a single category. This elaborated model correctly predicts the disappearance of the Category Effect when contexts are manipulated by varying the spacing of stimulus values rather than by varying their relative frequencies.

Adolescent↗
PubMedDate not supplied

Nocebo: the psychologic induction of pain.

More than two-thirds of an unselected sample of 34 college students reported mild headaches when told that a (nonexistent) electric current was passing through their heads. These reports appeared independent of whether the instructions emphasized the headache-producing effect of the current or whether the emphasis was on a perceptual task, with headache as only a possible side effect. The results are consistent with a view of pain as localized stress. They provide additional grounds for the suspicion that clinical focusing on pain may itself be a cause of pain.

Adult↗