Bruno Facon

Chronological Age, Receptive Vocabulary, and Syntax Comprehension in Children and Adolescents With Mental Retardation

This study was designed to examine the association of CA with syntax and vocabulary comprehension in children and adolescents with mental retardation. It was conducted using the PPVT-R and the Test for Reception of Grammar. The cognitive level of participants was estimated by means of three nonverbal intelligence tests. Results indicated that scores on intelligence tests account for 55% and 29% of the variability of syntax and vocabulary scores, respectively. For the vocabulary, the introduction of CA into the regression equation produced a significant increment of the variance explained (17%). However, its contribution to the variance of the syntax test was not significant. This finding suggests that CA-related experience is linked to on the receptive vocabulary of children and adolescents with mental retardation.

An item analysis of Raven's Colored Progressive Matrices among participants with Down syndrome

Standardized tests are widely used in intellectual disability research, either as dependent or control variables. Yet, it is not certain that their items give rise to the same performance in various groups under study. In the present work, 48 participants with Down syndrome were matched on their raw score on Ravens Colored Progressive Matrices (RCPM) with 48 participants with intellectual disability of undifferentiated etiology and 48 typical children. An item analysis was then conducted using the transformed item difficulties method, a statistical approach designed to detect differential item functioning between groups. Results showed that the difficulty of items was highly similar for the three groups. It is concluded that RCPM can be used with considerable confidence in comparative studies including typical, Down syndrome and intellectually disabled participants of undifferentiated etiology. Some methodological implications of these findings are discussed.

Chronological Age and Receptive Vocabulary of Persons with down Syndrome

The Test de Vocabulaire en Images (the French version of the Peabody Picture Vocabulary Test) and the Columbia Mental Maturity Scale were administered to 29 participants with Down syndrome aged 6.1 yr. to 13.0 yr. Analysis indicated a significant association between chronological age and the Test de Vocabulaire en Images mental age. This finding seems to suggest that the relationship between chronological age and the receptive vocabulary of persons with mental retardation is not specific to etiology.

CHRONOLOGICAL AGE AND PEABODY PICTURE VOCABULARY TEST PERFORMANCE OF PERSONS WITH MENTAL RETARDATION: NEW DATA '

The Test de Vocabulaire en Images (the French version of the Peabody Picture Vocabulary Test) and the Columbia Mental Maturity Scale were administered to 44 persons with mental retardation who were aged 6.8 yr. to 18.2 yr. Analysis indicated a significant influence of chronological age on the Test de Vocabulaire en Images Mental Age. This influence of chronological age probably explains why receptive vocabulary tests consistently overestimate the IQ of persons with mental retardation.

Beyond matching on the mean in developmental disabilities research

The matching of groups is a traditional way to control for confounding variables in developmental disabilities research. The equivalency of means across groups is routinely checked for these variables, but not the homogeneity of their variances or the shapes of their distributions. In the present paper, it is argued that group matching can go seriously wrong unless it directly confronts the distributional concerns by the use of well-known statistical indices and very simple graphical displays of the distributions. The question of the equivalency of item response profiles is also addressed since two participants or two groups of participants can obtain the same overall score on the matching variable by passing different items. In this case, the matching cannot be considered satisfactory because of poor concordance between the molar (overall score) and molecular (item scores) levels of matching. Angoffs Delta plot method, a statistical approach for detecting differential item functioning across small groups is described. It is promising as a simple way to prove whole test/individual item correspondence and, in addition, a useful tool for making post hoc statistical analyses at the item level on the dependent variables.

Angoff's delta method revisited: improving DIF detection under small samples.

Most methods for detecting differential item functioning (DIF) are suitable when the sample sizes are sufficiently large to validate the null statistical distributions. There is no guarantee, however, that they will still perform adequately when there are few respondents in the focal group or in both the reference and the focal group. Angoffs delta plot is a potentially useful alternative for small-sample DIF investigation, but it suffers from an improper DIF flagging criterion. The purpose of this paper is to improve this classification rule under mild statistical assumptions. This improvement yields a modified delta plot with an adjusted DIF flagging criterion for small samples. A simulation study was conducted to compare the modified delta plot with both the classical delta plot approach and the Mantel-Haenszel method. It is concluded that the modified delta plot is consistently less conservative and more powerful than the usual delta plot, and is also less conservative and more powerful than the Mantel-Haenszel method as long as at least one group of respondents is small.

Item Purification Does Not Always Improve DIF Detection: A Counterexample With Angoff’s Delta Plot

Item purification is an iterative process that is often advocated as improving the identification of items affected by differential item functioning (DIF). With test-score-based DIF detection methods, item purification iteratively removes the items currently flagged as DIF from the test scores to get purified sets of items, unaffected by DIF. The purpose of this article is to highlight that item purification is not always useful and that a single run of the DIF method may return equally suitable results. Angoff’s Delta plot is considered as a counterexample DIF method, with a recent improvement to the derivation of the classification threshold. Several possible item purification processes may be defined with this method, and all of them are compared through a simulation study and a real data set analysis. It appears that none of these purification processes clearly improves the Delta plot performance. A tentative explanation is drawn from the conceptual difference between the modified Delta plot and the other traditional DIF methods.

A Controlled Single-Case Treatment of Severe Long-Term Selective Mutism in a Child with Mental Retardation.

The aim of the present study was to demonstrate the efficacy of combining two operant learning procedures--shaping and fading--for treating selective mutism. The participant was a 12-year-old boy with mental retardation presenting a severe long-term selective mutism. The treatment was aimed at increasing the loudness of his vocalizations in an increasingly social milieu. The treatment was conducted over the course of about 20 weeks, with four 15-minute sessions per week. A gradual increase in speech loudness was observed. Data indicated a close correspondence between the changes in speech loudness and the criteria for reinforcement successively applied by the therapist, thereby confirming the causal link between the childs progress and the changes in reinforcement contingencies. In addition, good generalization was noted during the stimulus fading phase. Six-month follow up showed that loudness of verbalizations was still satisfactory in the classroom despite a change of school and peer group. The impressive improvement of the childs verbal behavior shows that the implementation of a treatment package including both shaping and stimulus fading is a worthwhile therapeutic option, even in the case of severe long-term selective mutism associated with mental retardation.

Evaluation of toy variation on engagement in a leisure activity of two children with profound multiple handicaps.

We conducted two studies to examine whether satiation occurs during leisure activities for children with profound multiple handicaps and whether it can be prevented by the alternate use of a sufficient number of different toys. The two studies were done in a training program in which the use of a switch connected to battery-operated toys was taught to two children with profound multiple handicaps. In Study I (Child 1), two experimental conditions were compared: variation (use of 5 toys in the same learning session) and identity (use of only one of these toys throughout the session). The variation condition produced higher and more stable performance than the identity condition, which yielded a progressive decrease in the appearance of the target behavior. In Study 2 (Child 2), satiation appeared from one session to another and the rate of responding increased when a new toy was presented. Some practical and theoretical implications are discussed.

Chronological Age and Performance of Persons with Mental Retardation on Verbal Subtests of the Wechsler Intelligence Scale for Children—Revised, French Version

The influence of chronological age on verbal intelligence of persons with mental retardation was studied using the French version of the Wechsler Intelligence Scale for Children-Revised. Participants were 1,101 children and adolescents divided into two groups according to the severity of mental retardation. The first group included 551 participants with moderate mental retardation, the second 550 participants with mild mental retardation. Analyses indicated a significant association between chronological age and raw scores on the four Verbal Comprehension subtests, even with performance on Perceptual Organization and Freedom from Distractibility subtests held constant. This finding suggests the relationship between chronological age and verbal intelligence is valid for persons with moderate mental retardation as well as for those with mild mental retardation.