1,721,042 research outputs found
Diagnosi di dislessia: una soluzione bivariata ad un problema bivariato. Un commento a «Indice di Efficienza della Lettura (IEL)», di D'Antuono, Savelli, Stella.
No full textThe problem of how developmental dyslexia should be diagnosed on grounds
of both speed and accuracy of reading performance can be solved by focusing on the bivariate
nature of the problem, as an alternative to using aggregate scores that combine both measures
but whose theoretical/pragmatical meaning is uncertain. The TERD worksheet, available online,
provides the Mahalanobis distance, an absolute and continuous bivariate measure that informs about how far the assessed subject is from the normative sample taking speed, accuracy, and their correlation into account, and also provides a p-value that can be used in diagnosis. TERD is very simple to use and does not require any manual computation – it just requires the user to insert raw (or adequately adjusted) scores in a table
Dissociations in neuropsychological single-case studies: Should one subtract raw or standardized (z) scores?
No full textThis work tackles the problem of whether the dissociation between two performances in a single-case study should be computed as the difference between the raw or between the standardized (e.g. z) scores. A wrong choice can lead to serious inflation of the probability of finding false dissociations and missing true dissociations. Two common misconceptions are that (i) standardized scores are a universally valid choice, or (ii) raw scores can be subtracted when the two performances concern the same “task/test”, otherwise standardized scores are better. These and other rules are shown to fail in specific cases and a solution is proposed in terms of in-depth analysis of the meaning of each score. The scores that should be subtracted are those that better reflect “deficit severities” – the latent, unobservable degrees of damage to the cognitive systems that are being compared. Thus explicit theoretical modelling of the investigated cognitive function(s) – the “scenario” – is required. A flowchart is provided that guides such analysis, and shows how a given neuropsychological scenario leads to the selection of an appropriate statistical method for detecting dissociations, introducing the critical concept of “deficit equivalence criterion” – the definition of what exactly a non-dissociation should look like. One further, overlooked problem concerning standardized scores in general (as measures of effect size, of which neuropsychological dissociations are just one example) is that they cannot be meaningfully compared if they have different reliabilities. In conclusion, when studying dissociations, increases in false-positive and false-negative risks are likely to occur when no explicit neuropsychological theory is offered that justifies the definition of what are to be considered as equivalent deficit severities in both performances, and which would lead to appropriate selection of raw, standardized, or any other type of score. More generally, the choice of any measure in any research context needs explicit theoretical modelling, without which statistical risks cannot be controlled
Revisiting multifactorial models of dyslexia: Do they fit empirical data and what are their implications for intervention?
No full textDevelopmental dyslexia can be viewed as the result of the effects of single deficits or multiple deficits. This study presents a test of the applicability of a multifactor-interactive model (MFi-M) with a preliminary set of five variables corresponding to different neuropsychological functions involved in the reading process. The model has been tested on a sample of 55 school-age children with developmental dyslexia. The results show that the data fit a model in which each variable contributes to the reading ability in a non-additive but rather interactive way. These findings constitute a preliminary validation of the plausibility of the MFi-M, and encourage further research to add relevant factors and specify their relative weights. It is further discussed how subtype-based intervention approaches can be a suitable and advantageous framework for clinical intervention in a MFi-M perspective
The influence of contralesional targets on the cancellation of ipsilesional targets in unilateral neglect
No full textMisprojection of landmarks onto the spatial map
No full textIt has been suggested that neglect patients misrepresent the metric spatial relations along the horizontal axis (anisometry). The "fabric" of their internal spatial medium would be distorted in such a way that physically equal distances appear relatively shorter on the contralesional side (canonical anisometry). The case of GL, a 76-year-old lady with left neglect on visual search tasks, is presented. GL showed severe relative overestimation on the left (contralesional) side on two independent tasks evaluating the metrics of her internal representation. A qualitatively similar pattern was found in two out of 10 other neglect patients who performed the second task. This behavior cannot be accounted for by the canonical anisometry hypothesis. Nevertheless, GL produced a relative left overextension (underestimation) when trying to set the endpoints of a virtual line given its midpoint (Endpoints Task). An interpretation of these results is offered in terms of a misprojection of relevant landmarks onto the internal representation without assuming distortion of its "fabric.
Basi fisiologiche dell’attività psichica
No full textCapitolo riguardante gli elementi fondamentali delle Neuroscienze per studenti universitari
Error analysis at the level of single moves in Block Design
No full textThe method of error analysis has been fruitfully applied to the performance of brain-damaged patients in a number of different domains. This approach has also been used for investigating the visuo-constructional abilities of neurological patients, but only in a limited fashion. In the present work we applied error analysis to the performance of three patients, each showing a different pattern of errors, and 12 controls on a modified version of the WAIS Block Design task. Data were collected about the single moves made by the subjects to arrive at a copy of the model, and errors were classified using 14 categories. The error patterns of the three patients were found to be reliably different and so putatively suggest different processing impairments. Patient BV showed errors possibly reflecting the lack, or absence, of a plan during the reproduction attempt. Patient GP mainly showed errors reflecting impairment in the processing of metric spatial relations, while patient VQ's errors were those predicted by impaired mental rotation ability. Overall, we showed that Block Design performance can be used productively in the investigation of spatial processing by means of the single-case approach
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