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Franco Pestilli, Keith Main, Jason Yeatman, Aviv Mezer, Ryan Martin, Stephanie Phipps, Brian Wandell; Speed discrimination performance in adults but not children correlates with single-word reading rate. Journal of Vision 2012;12(9):764. doi: 10.1167/12.9.764.
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© ARVO (1962-2015); The Authors (2016-present)
Adults with developmental dyslexia have poor speed discrimination performance (Demb et al. 1998; Eden, et al. 1996). We investigated whether there is a corresponding relationship between reading skill and speed-discrimination performance in children.
We measured speed-discrimination, contrast-detection and reading in 28 subjects (14 adults, age 21-36; 14 children, age 6-16). Reading performance: Reading skills were assessed using an age-normed psychometric test of word reading efficiency (TOWRE) that measures the number of (1) frequent words, and (2) pseudowords, the subject can read in 45 seconds. Thresholds were assessed at mesopic luminance levels (4 cd/m2) in order to target the magnocellular pathway. Speed-discrimination: Drifting gratings (0.5 c/deg, contrast randomized between 16 and 24%, base speed 38 deg/s) were presented at fixation in two consecutive intervals. Observers indicated the interval containing the faster stimulus. Contrast detection: A grating (0.5 c/deg, diameter, 38 deg/s) with variable contrast was presented in one of two temporal intervals, and observers indicated the interval containing the grating.
In adults single-word reading performance correlates with speed-discrimination thresholds (r = -0.617). In children, speed-discrimination thresholds are higher than adults (0.38º/s vs. 0.14º/s); performance does not correlate significantly with single-word reading (r=0.196). In both children and adults, pseudoword reading performance does not correlate significantly with speed-discrimination thresholds (r = -0.032; -0.135). In both groups single-word and pseudoword reading performance is independent of contrast detection threshold (adults: r=-0.137; -0.330; children: r=0.175; -0.104). The detection threshold levels are comparable in adults and children, (1.4%, 1.6%, respectively) indicating that speed discrimination differences are not explained by a general performance deficit in children. Hidden formatting deleted.
Speed-discrimination is a late-developing perceptual skill (Ahmed et al., 2005; Ben-Shachar, et al. 2007). Speed-discrimination does not covary with reading performance during development.
Meeting abstract presented at VSS 2012
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