Information processing deficits in children with attention-deficit/hyperactivity disorder, inattentive type, and children with reading disability

We examined the information processing capabilities of children diagnosed with the inattentive subtype of attention-deficit/hyperactivity disorder (ADHD) who had been characterized as having a sluggish cognitive tempo. Children referred for school-related problems (n = 81) and nonreferred community controls (n = 149) participated. Of the referred children, 24 met criteria for ADHD, 42 met criteria for reading disability (RD), and 9 of these were comorbid for RD and ADHD. Children with ADHD differed from those without ADHD on a visual search task but not on an auditory processing task; the reverse was true for children with RD. Decomposition of the visual search task into component operations demonstrated that children in the ADHD group had a slow processing rate that was not attributable to inattention. The children with ADHD were not globally poor at information processing or inattentive, but they demonstrated diminished speed of visual processing.     

Estimation of Item Response Theory Parameters in the Presence of Missing Data

Missing data are a common problem in a variety of measurement settings, including responses to items on both cognitive and affective assessments. Researchers have shown that such missing data may create problems in the estimation of item difficulty parameters in the Item Response Theory (IRT) context, particularly if they are ignored. At the same time, a number of data imputation methods have been developed outside of the IRT framework and been shown to be effective tools for dealing with missing data. The current study takes several of these methods that have been found to be useful in other contexts and investigates their performance with IRT data that contain missing values. Through a simulation study, it is shown that these methods exhibit varying degrees of effectiveness in terms of imputing data that in turn produce accurate sample estimates of item difficulty and discrimination parameters.     

Comparison of NOHARM and DETECT in Item Cluster Recovery: Counting Dimensions and Allocating Items

This study examines the performance of a new method for assessing and characterizing dimensionality in test data using the NOHARM model, and comparing it with DETECT. Dimensionality assessment is carried out using two goodness-of-fit statistics that are compared to reference χ² distributions. A Monte Carlo study is used with item parameters based on a statewide basic skills assessment and the SAT. Other factors that are varied include the correlation among the latent traits, the number of items, the number of subjects, skewness of the latent traits, and the presence or absence of guessing. The performance of the two procedures is judged by the accuracy in determining the number of underlying dimensions, and the degree to which items are correctly clustered together. Results indicate that the new, NOHARM-based method appears to perform comparably to DETECT in terms of simultaneously finding the correct number of dimensions and clustering items correctly. NOHARM is generally better able to determine the number of underlying dimensions, but less able to group items together, than DETECT. When errors in item cluster assignment are made, DETECT is more likely to incorrectly separate items while NOHARM more often incorrectly groups them together.     

The "Revolution in chemistry and physics." Overthrow of a reigning paradigm or competition between contemporary research programs?

Recent revisionist interpretations of the chemical revolution have left intact the core of the traditional view that its central feature was the overthow of the phlogiston theory by the oxygen theory of combustion of Antoine Lavoisier. The central confrontation has been seen as that between the adherents of the chemical system that Lavoisier built around his theory and the form of the phlogiston theory defended by Joseph Priestley. This essay contends that Priestley's use of phlogiston was so loosely connected with the older phlogiston theories descended from that of Georg Ernst Stahl that the events at the heart of the chemical revolution should be viewed more as a competition between two rival new research programs than as the replacement of a reigning paradigm.     

A Family Focused Intervention Influences Hippocampal-Prefrontal Connectivity Through Gains in Self-Regulation

The stressors associated with poverty increase the risks for externalizing psychopathology; however, specific patterns of neurobiology and higher self-regulation may buffer against these effects. This study leveraged a randomized control trial, aimed at increasing self-regulation at ~11 years of age. As adults, these same individuals completed functional MRI scanning (M_age = 24.88 years; intervention n = 44; control n = 49). Functional connectivity between the hippocampus and ventromedial prefrontal cortex was examined in relation to the intervention, gains in self-regulation, and present-day externalizing symptoms. Increased connectivity between these brain areas was noted in the intervention group compared to controls. Furthermore, individual gains in self-regulation, instilled by the intervention, statistically explained this brain difference. These results begin to connect neurobiological and psychosocial markers of risk and resiliency.