Psychologists practicing in Canada must decide which set of normative data to use for the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV). The purpose of this study was to compare the interpretive effects of applying American versus Canadian normative systems in a sample of 432 Canadian postsecondary-level students who were administered the WAIS-IV as part of an evaluation for a learning disability, attention-deficit hyperactivity disorder, or other mental health problems. Employing the Canadian normative system yielded IQ, Index, and subtest scores that were systematically lower than those obtained using the American norms. Furthermore, the percentage agreement in normative classifications, defined as American and Canadian index scores within five points or within the same classification range, was between 49% and 76%. Substantial differences are present between the American and Canadian WAIS-IV norms. Clinicians should consider carefully the implications regarding which normative system is most appropriate for specific types of evaluations.
The present study assessed performance on symptom validity tests (SVTs) and various cognitive-processing measures to evaluate the impact of having attention-deficit hyperactivity disorder (ADHD) on SVT performance using a clinical sample of 73 children aged 7 to 18 years old who had a previous diagnosis of ADHD. Cognitive impairment associated with ADHD may lead these individuals to perform poorly on what are considered to be relatively easy but boring SVTs. Few clients in this sample returned a score pattern on the Word Memory Test, Medical Symptom Validity Test, or Nonverbal Medical Symptom Validity Test that would have classified them as having invested poor effort; the Computerized Assessment of Response Bias returned higher rates of failure. In the absence of a lifelong history of severe attention and impulse control problems, and especially where secondary gains exist for obtaining a diagnosis, clinicians should interpret low scores on these SVTs as indicating low effort or noncredible performance as opposed to failure due to the symptoms of ADHD.
Abstract Accurate identification of symptom magnification is essential when determining whether or not obtained test data are valid or interpretable. Apart from using freestanding symptom validity tests, many researchers encourage use of embedded measures of test-related motivation, including ones derived from the Digit Span subtest of the Wechsler scales. Such embedded measures are based on identification of performance patterns that are implausible if the test taker is investing full effort; however, it is unclear whether or not persons with preexisting cognitive difficulties such as specific learning disabilities (LD) might be falsely accused of poor test motivation due to actual but impaired working-memory skills. This study examined the specificity of such measures by reviewing performance of 86 adolescents with LDs on three measures embedded in the Wechsler Intelligence Scale for Children-Fourth Edition-namely, Digit Span (DS), Vocabulary-DS differences, and Reliable Digit Span (RDS) scores. Results indicate that while RDS is likely insensitive to impairments associated with LD, other DS measures may have an unacceptably high false-positive rate, especially if Canadian normative data are used to calculate scores.
Although eye movement onset typically precedes hand movement onset when reaching to targets presented in peripheral vision, arm motor commands appear to be issued at around the same time, and possibly in advance, of eye motor commands. A fundamental question, therefore, is whether eye movement initiation is linked or yoked to hand movement. We addressed this issue by having participants reach to targets after adapting to a visuomotor reversal (or 180° rotation) between the position of the unseen hand and the position of a cursor controlled by the hand. We asked whether this reversal, which we expected to increase hand reaction time (HRT), would also increase saccadic reaction time (SRT). As predicted, when moving the cursor to targets under the reversal, HRT increased in all participants. SRT also increased in all but one participant, even though the task for the eyes-shifting gaze to the target-was unaltered by the reversal of hand position feedback. Moreover, the effects of the reversal on SRT and HRT were positively correlated across participants; those who exhibited the greatest increases in HRT also showed the greatest increases in SRT. These results indicate that the mechanisms underlying the initiation of eye and hand movements are linked. In particular, the results suggest that the initiation of an eye movement to a manual target depends, at least in part, on the specification of hand movement.
Adaptation of reaching movements to visuomotor transformations is generally thought to involve implicit or procedural learning. However, there is evidence that explicit or cognitive processes can also play a role (Redding and Wallace, 2006 ). For example, the early phase of adaptation to a visuomotor rotation appears to involve spatial working memory processes linked to mental rotation (Anguera et al., 2010 ). Since it is known that cognitive processes like mental rotation lead to larger reaction times (Georgopoulos and Massey, 1987 ), here we explored the relation between reaction time (RT) and reach error reduction. Two groups of subjects adapted their reaching movements to a 60° visuomotor rotation either without RT constraints or with RT limited to 350 ms. In the unconstrained group, we found that adaption rate varied widely across subjects and was strongly correlated with RT. Subjects who decreased hand direction error (DE) rapidly exhibited prolonged RTs whereas little RT cost was seen in subjects who decreased DE gradually. RTs were also correlated with after-effects seen when the visuomotor rotation was removed. Subjects with the longest RTs exhibited the smallest after-effects. In the RT constrained group, all subjects exhibited gradual DE adaptation and large after-effects, similar to the fast responders in the free group. These results suggest that adaptation to a visuomotor rotation can involve processes that produce faster error reductions without increasing after-effects, but at an expense of larger reaction times. Possible candidates are processes related to spatial working memory, and more specifically, to mental rotation.
No clinically proven method currently exists to determine if a test taker is feigning or exaggerating symptoms of a specific reading disability (RD) for potential secondary gain (i.e., extra time on examinations, access to bursary funds, or tax benefits). Our objective was to examine the utility of previously proposed symptom validity measures (i.e., the Dyslexia Assessment of Simulation or Honesty [DASH] and the resulting Feigning Index [FI]) in discriminating students with genuine RDs from sophisticated simulators given ample time to prepare, who were warned that noncredible performance could be detected. The DASH correctly classified almost 83% of coached simulators with no false positives. The FI accurately classified 86% of post-secondary students feigning RD without misidentifying any students with a genuine RD, resulting in 91.8% overall classification accuracy. These two methods show promise as a means of detecting noncredible performance in the assessment of RD.
Identification of high-risk populations for serious infection due to S. pneumoniae will permit appropriately targeted prevention programs.
Related JoVE Video
Journal of Visualized Experiments
What is Visualize?
JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.
How does it work?
We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.
Video X seems to be unrelated to Abstract Y...
In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.