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Competing theories of dyslexia posit that reading difficulties arise from impaired visual, auditory, phonological, or statistical learning mechanisms. Importantly, many theories posit that dyslexia reflects a cascade of impairments emanating from a single “core deficit”. Here we report two studies evaluating core deficit and multifactorial models. In Study 1, we use publicly available data from the Healthy Brain Network to test the accuracy of phonological processing measures for predicting dyslexia diagnosis and find that over 30% of cases are misclassified (sensitivity = 66.7%; specificity = 68.2%). In Study 2, we collect a battery of psychophysical measures of visual motion processing and standardized measures of phonological processing in 106 school‐aged children to investigate whether dyslexia is best conceptualized under a core‐deficit model, or as a disorder with heterogenous origins. Specifically, by capitalizing on the drift diffusion model to analyze performance on a visual motion discrimination experiment, we show that deficits in visual motion processing, perceptual decision‐making, and phonological processing manifest largely independently. Based on statistical models of how variance in reading skill is parceled across measures of visual processing, phonological processing, and decision‐making, our results challenge the notion that a unifying deficit characterizes dyslexia. Instead, these findings indicate a model where reading skill is explained by several distinct, additive predictors, or risk factors, of reading (dis)ability., Using predictors from a visual motion processing experiment and linguistic measures, we show that a single‐mechanism model of reading disability cannot account for the range of linguistic and sensory processing outcomes observed in children. We propose an additive risk factor model where different aspects of sensory, cognitive and language function each contribute independently to reading development.

Objective : To elaborate normative values for a clinical psychophysical taste test ("Taste Strips”). Background : The "Taste Strips” are a psychophysical chemical taste test. So far, no definitive normative data had been published and only a fairly small sample size has been investigated. In light of this shortcoming for this easy, reliable and quick taste testing device, we attempted to provide normative values suitable for the clinical use. Setting : Normative value acquisition study, multicenter study. Methods : The investigation involved 537 participants reporting a normal sense of smell and taste (318 female, 219 male, mean age 44 years, age range 18-87 years). The taste test was based on spoonshaped filter paper strips ("Taste Strips”) impregnated with the four (sweet, sour, salty, and bitter) taste qualities in four different concentrations. The strips were placed on the left or right side of the anterior third of the extended tongue, resulting in a total of 32 trials. With their tongue still extended, patients had to identify the taste from a list of four descriptors, i. e., sweet, sour, salty, and bitter (multiple forcedchoice). To obtain an impression of overall gustatory function, the number of correctly identified tastes was summed up for a "taste score”. Results : Taste function decreased significantly with age. Women exhibited significantly higher taste scores than men which was true for all age groups. The taste score at the 10th percentile was selected as a cut-off value to distinguish normogeusia from hypogeusia. Results from a small series of patients with ageusia confirmed the clinical usefulness of the proposed normative values. Conclusion : The present data provide normative values for the "Taste Strips” based on over 500 subjects tested

The visual analogue scale (VAS) is an established, validated, self-report measure usually consisting of a 10 cm line on paper with verbal anchors labeling the ends. Palmtop computers (PTCs also known as personal digital appliances) have incorporated VAS entry by use of a touch screen. However, the validity and psychophysical properties of the electronic VAS have never been formally compared with the conventional paper VAS. The aim of this study is to determine the agreement between the electronic (eVAS) and paper (pVAS) modes. Twenty-four healthy volunteers were recruited for this study. Each study participant provided input using both measurement methods by marking the eVAS and pVAS in response to two kinds of stimuli, cognitive and sensory. A verbal rating scale of seven descriptors of intensity represented the cognitive stimuli. Participants were asked to mark the location that best corresponded to the pain intensity described by each word on scales from 'no pain' to 'worst possible pain'. The sensory stimuli used were a set of test weights consisting of plastic containers ranging from 7 to 129 g. The VAS for sensory stimuli ranged from 0 (no weight) to 'reference weight' (the heaviest weight outside the range of test weights). There were two types of input stimuli and two modes for recording responses for a total of four experimental conditions. Two evaluators independently measured and recorded all the pVAS forms to the nearest millimeter. A total of 2016 stimuli were rated. The overall correlation for ratings of both sensory and cognitive stimuli on eVAS and pVAS was r = 0.91. For paired verbal stimuli the correlation was r = 0.97. For paired sensory stimuli the correlation was r = 0.86. The correlation between group eVAS and pVAS ratings to common verbal stimuli was r = 0.99. For common sensory stimuli the group correlation was r = 0.99. The median of correlations comparing eVAS and pVAS ratings was 0.99 for verbal stimuli and 0.98 for sensory stimuli. Multivariate analyses showed equivalent stimuli to be rated much the same whether entered on paper VAS or PTC touch screen VAS (P < 0.0001). Support was found for the validity of the computer version of the VAS scale.

Professional artists seem to develop a preference for certain types of pencils and paper (Akyuz 1995 ). While theaesthetic outcome may be the obvious reason for this preference, haptic feedback may also play a role in selecting media (Prytherch and Jerrard 2001 , 2003 ). This suggestion implies that artists may be sensitive to vibrotactile signals resulting from the interaction between pencil and paper during drawing. Tribological tests showed that H-range leads generate more resistance than B-range pencils when writing on a standard 80 g/m 2 paper. Moreover, a constant stimulus 2IFC procedure showed that Fine Arts students found it easier to discriminate between H-range and HB than B-range and an HB. This suggests that the human haptic system may be sensitive to the vibrotactile signals generated by the differences in resistance resulting from the interaction of leads with the paper's textured surface. Implications for pencil manufacturing and simulations of virtual writing are discussed. Statement of Relevance: The study assesses the tactile sensitivity of Fine Artists to the physical properties of the interaction between different types of lead and a standard printing paper. The results may help in designing more responsive drawing instruments as well as more realistic virtual drawing interfaces.

The increased use of CRT monitors for displaying and controlling stimuli in studies of surface color poses problems of comparability with data obtained with traditional paper-and-illuminant methods. A review of comparable studies using the two methodologies revealed that CRT studies tend to report larger contrast effects. To investigate factors that may be responsible for this difference, simultaneous lightness contrast was measured using both CRT and paper-and-illuminant presentations. The spatial distribution of luminance in the whole field of view and the visual angles subtended by the displays were controlled. The CRT presentation yielded contrast effects twice as big as those measured for a paper surface in a homogeneously illuminated room. However, a paper display under Gelb lighting yielded almost exactly the same effect size as that measured in the CRT presentation. These results demonstrate that contrast effects in both modes of presentation are affected by the spatial distribution of luminance beyond the basic experimental stimuli.