Contrast sensitivity functions and specific reading disability

Lovegrove, William; Martin, F; Bowling, Alison C; Blackwood, Mary; Badcock, David R.; Paxton, Susan J.

doi:10.1016/0028-3932(82)90105-1

Cited by 125 publications

(50 citation statements)

References 6 publications

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“…Contrast sensitivity was tested using grayscale vertical sine wave gratings of 0.5, 1, 2, 4, 6, 8, 10, and 12 cpd. These spatial frequencies were chosen to conform to previous psychophysical studies of spatial frequency sensitivity (e.g., Campbell & Robson, 1968;Ginsburg, 1986;see Graham, 1989, for a review) and to cover the range of spatial frequencies used in previous studies with dyslexic individuals (Borsting et al, 1996;Cornelissen, 1993;Demb et al, 1998;Evans et al, 1993Evans et al, , 1996Lovegrove et al, 1980;Lovegrove et al, 1982;Martin & Lovegrove, 1984see Skottun, 2000, for a review). Each vertical sine wave grating was multiplied by a circular bitmap with a Gaussian intensity profile to avoid abrupt luminance transits.…”

Section: Contrast Sensitivitymentioning

confidence: 99%

“…Numerous researchers have found that dyslexic and nondyslexic controls exhibit different patterns of sensitivity to spatial frequencies (e.g., Borsting et al, 1996;Cornelissen, 1993;Demb, Boynton, Best, & Heeger, 1998;Evans, Drasdo, & Richards, 1993, 1996Gross-Glenn et al, 1995;Lovegrove, Bowling, Badcock, & Blackwood, 1980;Lovegrove et al, 1982;Martin, Cornelissen, Fowler, & Stein, 1993;Martin & Lovegrove, 1984. In particular, studies indicate that dyslexic individuals have reduced sensitivity to certain spatial frequencies and that this reduction tends to be greatest in the low-to midfrequency range (i.e., between 2 and 8 cpd; Borsting et al, 1996;Cornelissen, 1993;Demb et al, 1998;Evans et al, 1993Evans et al, , 1996Lovegrove et al, 1980;Lovegrove et al, 1982, Experiment 2;Martin & Lovegrove, 1984see Skottun, 2000, for a review).…”

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confidence: 99%

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Assessing the role of different spatial frequencies in word perception by good and poor readers

Patching

Jordan

2005

Memory & Cognition

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Numerous studies indicate that dyslexic and nondyslexic individuals exhibit different patterns of sensitivity to spatial frequency. However, the extension of this effect to normal (nondyslexic) adults of good and poor reading abilities and the role played by different spatial frequencies in word perception have yet to be determined. In this study, using normal (nondyslexic) adults, we assessed reading ability, spatial frequency sensitivity, and perception of spatially filtered words and nonwords (using a twoalternative forced choice paradigm to avoid artifactual influences of nonperceptual guesswork). Good and poor readers showed different patterns of spatial frequency sensitivity. However, no differences in accuracy of word and nonword perception were found between good and poor readers, despite their differences in spatial frequency sensitivity. Indeed, both reading abilities showed the same superior perceptibility for spatially filtered words over nonwords across different spatial frequency bands. These findings indicate that spatial frequency sensitivity differences extend to normal (nondyslexic) adult readers and that a range of spatial frequencies can be used for word perception by good and poor readers. However, spatial frequency sensitivity may not accurately reveal an individual's ability to perceive words.

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Section: Contrast Sensitivitymentioning

confidence: 99%

mentioning

confidence: 99%

Assessing the role of different spatial frequencies in word perception by good and poor readers

Patching

Jordan

2005

Memory & Cognition

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“…An irregular magnocellular system could reduce the visual sensitivity for moving or flickering stimuli (Cornelissen et al, 1998a) and therefore to interfere with lexical decision tasks (Cornelissen et al, 1998b) or the detection of small letters (Stein and Walsh, 1997) for example. Since the earliest studies (Lovegrove et al, 1980(Lovegrove et al, , 1982(Lovegrove et al, , 1986) sinusgratings have been one of the most popular experimental means. Depending on the spatial frequency (cycles of the bright and dark bars per degree visual angle) dyslexics showed a reduced sensitivity (Evans et al, 1994;Kubová et al, 1995) for motion detection.…”

Section: Introductionmentioning

confidence: 99%

Visual information processing in dyslexic children

Scheuerpflug

Plume

Vetter

et al. 2004

Clinical Neurophysiology

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“…Detection of stimulus attributes such as high spatial frequencies, low temporal frequencies and colour dierences depend more on the sensitivity of parvocells [26,37,48]. Sensitivity for these stimulus parameters are usually unimpaired in dyslexics [10,28,31,33,34]. Some psychophysical studies have failed to con®rm that such visual de®cits are associated with dyslexia ( [20,21,61], see also, [17] for review).…”

Section: Introductionmentioning

confidence: 99%

Visual motion sensitivity in dyslexia: evidence for temporal and energy integration deficits

et al. 2000

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In addition to poor literacy skills, developmental dyslexia has been associated with multisensory de®cits for dynamic stimulus detection. In vision these de®cits have been suggested to result from impaired sensitivity of cells within the retino-cortical magnocellular pathway and extrastriate areas in the dorsal stream to which they project. One consequence of such selectively reduced sensitivity is a diculty in extracting motion coherence from dynamic noise, a de®cit associated with both developmental dyslexia and persons with extrastriate, dorsal stream lesions. However the precise nature of the mechanism(s) underlying these perceptual de®cits in dyslexia remain unknown. In this study, we obtained motion detection thresholds for 10 dyslexic and 10 control adults while varying the spatial and temporal parameters of the random dot kinematogram (RDK) stimuli. In Experiment 1 stimulus duration was manipulated to test whether dyslexics are speci®cally impaired for detecting short duration, rather than longer stimuli. Dot density was varied in Experiment 2 to examine whether dyslexics' reduced motion sensitivity was aected by the amount of motion energy present in the RDKs. Dyslexics were consistently less sensitive to coherent motion than controls in both experiments. Increasing stimulus duration did not improve dyslexics' performance, whereas increasing dot density did. Thus increasing motion energy assisted the dyslexics, suggesting that their motion detectors have a lower signal to noise ratio, perhaps due to spatial undersampling. 7

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Contrast sensitivity functions and specific reading disability

Cited by 125 publications

References 6 publications

Assessing the role of different spatial frequencies in word perception by good and poor readers

Assessing the role of different spatial frequencies in word perception by good and poor readers

Visual information processing in dyslexic children

Visual motion sensitivity in dyslexia: evidence for temporal and energy integration deficits

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