The Composition Of Normative Groups And Diagnostic Decision Making: Shooting Ourselves In The Foot

Purpose: The normative group of a norm-referenced test is intended to provide a basis for interpreting test scores. However, the composition of the normative group may facilitate or impede different types of diagnostic interpretations. This article considers who should be included in a normative sample and how-this decision must be made relative to the purpose for which a test is intended. Method: The way in which the composition of the normative sample affects classification accuracy is demonstrated through a test review followed by a simulation study. The test review examined the descriptions of the normative group in a sample of 32 child language tests. The mean performance reported in the test manual for the sample of language impaired children was compared with the sample's norms, which either included or excluded children with language impairment. For the simulation, 2 contrasting normative procedures were modeled. The first procedure included a mixed group of representative cases (language impaired and normal cases). The second procedure excluded the language impaired cases from the norm. Results: Both the data obtained from test manuals and the data simulation based on population characteristics supported our claim that use of mixed normative groups decreases the ability to accurately identify language impairment. Tests that used mixed norms had smaller differences between the normative and language impaired groups in comparison with tests that excluded children with impairment within the normative sample. The simulation demonstrated mixed norms that lowered the group mean and increased the standard deviation, resulting in decreased classification accuracy. Conclusions: When the purpose of testing is to identify children with impaired language skills, including children with language impairment in the normative sample can reduce identification accuracy.Communication Sciences and Disorder

Attentional Control in Preschool Children with Specific Language Impairment

This research was guided by a theoretical framework positing that children with typical language apply general cognitive resources, such as attention, to facilitate language acquisition, and limitations in these processes may contribute to poor language skills. From this perspective, studying the attentional functioning of children who exhibit difficulty with language would have value for both informing this theory and understanding the nature of the disorder. However, research on the attention of children with specific language impairment (SLI) is limited, as only a few subdomains have been addressed to date. In addition, although school-age children with SLI have been studied, the assessment of attentional functioning in preschool children with this disorder has been minimal. This is likely the result the limitations inherent to the methods used for evaluating attentional skills at younger ages. The purpose of this research was to extend a method previously used successfully with preschool children to study selected aspects of attentional control including susceptibility to distraction, inhibitory control, and updating skills. The research questions were: (a) Do children with SLI exhibit increased susceptibility to distraction relative to their typically-developing peers, and if so, does it vary according to the type of distracter (visual, nonverbal-auditory, linguistic) presented? (b) Do children with SLI exhibit poor inhibitory control relative to their typically-developing peers? (c) Do children with SLI and their typically-developing peers display evidence of updating? Thirty-one preschool children with SLI and 31 controls participated in two computer tasks designed to assess these mechanisms of attentional control. The susceptibility to distraction task involved resisting distracters presented in different stimulus modalities (visual and auditory-linguistic/nonlinguistic). Inhibition and updating skills were assessed using a stop signal paradigm. In comparison to typically-developing children, the children with SLI exhibited increased susceptibility to distraction and poor inhibitory control. Unlike the controls, they exhibited no evidence of updating. The results of this investigation will contribute to a long-term goal of addressing how attention may affect language acquisition in children with SLI. In addition, the successful methodology employed in this study may offer an improved procedure for diagnosing attentional difficulties at an early age, regardless of language status