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Biomedical subjects

P De Boeck

Publications and source records attributed to P De Boeck.

17 recordsLinked to original sources
PubMed2001

The effect of ignoring item interactions on the estimated discrimination parameters in item response theory.

Most item response theory models assume conditional independence, and it is known that interactions between items affect the estimated item discrimination. In this article, this effect is further investigated from a theoretical perspective and by means of simulation studies. To this end, a parametric model for item interactions is introduced. Next, it is shown that ignoring a positive interaction results in an overestimation of the discrimination parameter in the two-parameter logistic model (2PLM), whereas ignoring a negative interaction leads to an underestimation of the parameter. Furthermore, it is demonstrated that in some cases the item characteristic curves of the 2PLM and of an item involved in an interaction are quite similar, indicating that the 2PLM can provide a good fit to data with interactions.

Humans↗
PubMed2001

Some Mantel-Haenszel tests of Rasch model assumptions.

A class of Rasch model tests is proposed, all of them based on the Mantel-Haenszel chi-squared statistic. All tests make use of the 'sufficient statistics' property the Rasch model possesses. One element of our general class, the test for item bias developed by Holland and Thayer, has been discussed extensively in the psychometric literature. Three applications of the general procedure are presented, two on unidimensionality and one on item dependence in educational testing. In each case, simulation results are reported. Our procedure is also applied to real data.

Data Interpretation, Statistical↗
PubMed2001

Propositional reasoning: the differential contribution of "rules" to the difficulty of complex reasoning problems.

In Experiment 1, complex propositional reasoning problems were constructed as a combination of several types of logical inferences: modus ponens, modus tollens, disjunctive modus ponens, disjunctive syllogism, and conjunction. Rule theories of propositional reasoning can account for how one combines these inferences, but the difficulty of the problems can be accounted for only if a differential psychological cost is allowed for different basic rules. Experiment 2 ruled out some alternative explanations for these differences that did not refer to the intrinsic difficulty of the basic rules. It was also found that part of the results could be accounted for by the notion of representational cost, as it is used in the mental model theory of propositional reasoning. However, the number of models as a measure of representational cost seems to be too coarsely defined to capture all of the observed effects.

Adolescent↗
PubMed2001

Categorization of novel stimuli in well-known natural concepts: a case study.

In this study, we investigated to what extent exemplar-based and prototype predictors can be applied to predicting categorization in natural language concepts. Participants categorized novel tropical foods into two well-known natural language concepts: fruits and vegetables. The results indicate that both the prototype predictors and the exemplar predictors contribute significantly in accounting for the categorization choices but that the contribution of the prototype predictor comes from just a limited number of features.

Adolescent↗
PubMed1999

Simple mental addition in children with and without mild mental retardation.

The speeded performance on simple mental addition problems of 6- and 7-year-old children with and without mild mental retardation is modeled from a person perspective and an item perspective. On the person side, it was found that a single cognitive dimension spanned the performance differences between the two ability groups. However, a discontinuity, or "jump," was observed in the performance of the normal ability group on the easier items. On the item side, the addition problems were almost perfectly ordered in difficulty according to their problem size. Differences in difficulty were explained by factors related to the difficulty of executing nonretrieval strategies. All findings were interpreted within the framework of Siegler's (e.g., R. S. Siegler & C. Shipley, 1995) model of children's strategy choices in arithmetic. Models from item response theory were used to test the hypotheses.

Case-Control Studies↗
PubMed1999

A two-process theory of facial perception of emotions.

A two-process probabilistic theory of emotion perception based on a non-linear combination of facial features is presented. Assuming that the upper and the lower part of the face function as the building blocks at the basis of emotion perception, an empirical test is provided with fear and happiness as target emotions. Subjects were presented with prototypical fearful and happy faces and with computer-generated chimerical expressions that were a combination of happy and fearful. Subjects were asked to indicate the emotions they perceive using an extensive list of emotions. We show that some emotions require a conjunction of the two halves of a face to be perceived, whereas for some other emotions only one half is sufficient. We demonstrate that chimerical faces give rise to the perception of genuine emotions. The findings provide evidence that different combinations of the two halves of a fearful and a happy face, either congruent or not, do generate the perception of emotions other than fear and happiness.

Association Learning↗
PubMed1999

Predicting conjunction typicalities by component typicalities.

In two studies, we investigated to what extent typicalities in conjunctive concepts phrased as relative clauses--such as pets that are also birds--can be predicted from simple functions of constituent typicalities and from extensions of such functions. In a first study, analyses of a large aggregated data set, based on seven different experiments, showed that a calibrated minimum rule model and some extensions of this model accounted for a very large part of the variance in the conjunction typicalities. The same models can also account for the so-called guppy effect. A psychological explanation is presented, which states that typicalities in contrast categories, like pets that are not birds and birds that are not pets, further improve the prediction of conjunction typicalities. This hypothesis is tested in a second study.

Adult↗
PubMed1998

Self-concept and mood: a comparative study between depressed patients with and without borderline personality disorder.

Within the framework of Self-Structure Theory, this study investigated the relationship between depressed mood and Borderline Personality Disorder (BPD) on self and others descriptions, with a special emphasis on the self-structure's valence, that is, its affective, negative and/or positive content. Seventeen DSM-III-R unipolar depressed patients with associated BPD (DSM-III-R axis II) and twelve unipolar depressed patients without BPD were compared to eighteen non-psychiatric controls on four measures of evaluation and of affective discrepancy of descriptions of self and others. Subjects were administered the grid repertory technique. The analysis of the resulting two-way valence matrix, with attributions as columns, and self and others as rows, showed that depressed patients with and without BPD differed from the non-psychiatric controls with regard to negativity of the descriptions. As compared with the two other groups, depressed patients with BPD showed a distinctive pattern characterised by the joint presence of a negative view of self and a larger affective discrepancy for others, with others being conjunctively assigned positive and negative attributes. Despite some limitations, the distinctive pattern evidenced corroborates the conflicted interpersonal relationship and is in keeping with clinical theorising on BPD.

Adult↗
PubMed1998

Not guppies, nor goldfish, but tumble dryers, Noriega, Jesse Jackson, panties, car crashes, bird books, and Stevie Wonder.

This paper focuses on the guppy effect (Osherson & Smith, 1981), that is, on the existence of examples of conjunctive concepts that are more typical of the conjunction than of both constituents. The most frequently given examples of this effect, guppy and goldfish, are shown not to be more typical of the conjunction pet fish than of fish in two between-subjects and one within-subjects experiment. The frequency of the effect in a large empirical study is investigated, and better examples of the effect are suggested.

Cognition↗
PubMed1994

Person identification and self-concept in the delusional misidentification syndrome. A case study.

This study on a delusional misidentification patient with both Frégoli symptoms and intermetamorphosis investigates the cognitive structure of others and of the self-representations with a new clustering method (HICLAS conjunctive model). Results show that this patient, free from face recognition disorders, shows severe structural anomalies in the mapping of misidentified others, and of the self. Disturbances in the cognitive structure and person identification are discussed in reference to a psychopathological explanation of the misidentification syndrome.

Adult↗
PubMed1993

Part-instance association in the categorization of acts.

Rips and Conrad (1989) found a kind-part reciprocal effect in models of the mind, in that one mental activity is part of another if the second is a kind of the first, and vice versa. In the present paper, we hypothesize that a formally analogous effect occurs at the level of activity instances. In particular, we hypothesize that an act is judged to be an instance of an act category referred to by an activity verb if the activity is judged to be an important part of the act, and vice versa. Empirical support for this hypothesis is found in three studies with activity verbs. The converse part-instance relation is further noted to parallel the part-instance association for a specific type of metonymically defined categories. Rips and Conrad's kind-part reciprocal effect is shown to be a logical consequence of the converse part-instance relation.

Attention↗
PubMed1981

Research findings on the nature of constructs in schizophrenics.

Using a personal construct theory approach, Radley (1974) proposes a theoretical view about the nature and genesis of schizophrenic thought disorder. In this study, we replicate some results of previous studies on which Radley relies and we test some implications of his view. A test, consisting of the four possible combinations of elicited and supplied constructs and elicited and supplied elements was administered on group of schizophrenics, part of them being thought disordered (TD), part of them being not thought disordered (NTD) at the moment of testing and on a matched group of normals. An additional test was administered in order to obtain a maldistribution score. Our findings confirm most of the characteristics of the TD and NTD phase in schizophrenics, as proposed by Radley and they suggest some additions to that view. Moreover, they call for some changes in the scoring system of the Grid Test for Schizophrenic Thought Disorder (Bannister & Fransella, 1967) by using the Element Consistency, Social Agreement and maldistribution scores and Intensity and Differentiation scores of only the retest.

Adult↗
PubMedDate not supplied

Identity disturbances and self-other differentiation in schizophrenics, borderlines, and normal controls.

The present study investigates identity disorders in schizophrenics and borderlines. Nineteen schizophrenics and 17 borderlines were compared with 18 normal controls. The technique used was an adapted version of the repertory grid test to describe the self and nine significant others (i.e., family members). Three indices were derived from the 10 person x 20 self-generated-attribute matrix to measure the extent to which self was differentiated from others: (1) overlap of salient attributes, (2) overlap of opposite attributes, and (3) degree of differentiation among others. Results showed that both schizophrenics and borderlines describe themselves more in terms of opposites than in terms of salient attributes. Differentiation among significant others was severely impaired in schizophrenics and preserved in borderlines. These findings were interpreted as a failure of the individuation process in schizophrenics and as an incomplete construal of self-identity in borderlines.

Adult↗