The influence of color on transient system activity: Implications for dyslexia research

Pammer, Kristen; Lovegrove, William

doi:10.3758/bf03194415

Cited by 16 publications

(23 citation statements)

References 53 publications

(38 reference statements)

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“…This suggests that red surrounds decrease P contrast sensitivity. These results could be explained by the fact that we did not attempt to match color contrast levels between the gray pedestals and the red and green backgrounds (Pammer & Lovegrove, 2001). Hence, we repeated the experiment with all red and all green stimuli.…”

Section: Discussionmentioning

confidence: 98%

The effects of red surrounds on visual magnocellular and parvocellular cortical processing and perception

et al. 2018

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More than 50 years ago, Hubel and Wiesel identified a subpopulation of geniculate magnocellular (M) neurons that are suppressed by diffuse red light. Since then, many human psychophysical studies have used red and green backgrounds to study the effects of M suppression on visual task performance, as a means to better understand neurodevelopmental disorders such as dyslexia and schizophrenia. Few of these studies have explicitly assessed the relative effects of red backgrounds on the M and P (parvocellular) pathways. Here we compared the effects of red and green diffuse background illumination on well-accepted cortical M and P signatures, both physiologically through nonlinear analysis of visual evoked potentials (VEPs; N = 15), and psychophysically through pulsed and steady pedestal perceptual thresholds (N = 9 with gray pedestals and N = 8 with colored pedestals). Red surrounds reduced P-generated temporal nonlinearity in the VEPs, but they did not influence M-generated VEP signatures. The steady and pulsed pedestal results suggest that red surrounds can have different effects on M and P contrast sensitivities, depending on whether the target is colored gray or red, presented centrally or peripherally, or whether it is brighter or dimmer than the surround. Our results highlight difficulties in interpreting the effects of red backgrounds on human VEPs or perception in terms of M specific suppression.

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Section: Discussionmentioning

confidence: 98%

The effects of red surrounds on visual magnocellular and parvocellular cortical processing and perception

et al. 2018

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“…Psychophysical studies have revealed that the magnitude of metacontrast masking decreases on the presentation of a red background (Bedwell, Brown, & Miller, 2003;Breitmeyer & Williams, 1990;Edwards, Badcock, & Nishida, 1996;Pammer & Lovegrove, 2001). Global precedence effects in hierarchically organized stimuli were weaker with a red b background than with an equiluminant green background (Michimata, Okubo, & Mugishima, 1999).…”

mentioning

confidence: 99%

Inhibition of vection by red

Seno

Shoji

Ito

2010

Attention, Perception, & Psychophysics

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We investigated the effects of colors on vection induction. Expanding optical flows during one's forward d self-motion were simulated by moving dots. The dots and the background were painted in equiluminant red and green. Experiments 1 and 2 showed that vection was weaker when the background was red than when the background was green. In addition, Experiment d 3 showed that vection was weaker when the moving dots were red than when the dots were green. Experiment k 4 demonstrated that red dots on a red background induced very weak vection, as compared with green dots on a green background. In Experiments 5 and 6, we showed that the present results could not be explained by a luminance artifact. Furthermore, Experiment d 7 showed that a moving red grating induced weaker vection than did a green one. We concluded that a red visual stimulus inhibits vection.

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“…There may be an impairment in the suprathreshold sensitivity of the magnocellular system at the upper limit of temporal sensitivity, as evidenced by reports of lower flicker fusion thresholds in dyslexia . Otherwise, there may be an abnormality in the interaction between the magnocellular and parvocellular systems, as evidenced by abnormalities in visual masking and visual persistence (see Lovegrove, 1993), although a mixed pattern of positive and negative findings has also been reported for these tasks (Hayduk, Bruck, & Cavanagh, 1996;Pammer & Lovegrove, 2001). As in the case of visual flicker, there was no evidence for a loss of sensitivity to fast rates of modulation in the auditory modality.…”

Section: Discussionmentioning

confidence: 88%

A test of the magnocellular deficit theory of dyslexia in an adult sample

Stuart

McAnally

McKay

et al. 2006

Cognitive Neuropsychology

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An influential theory of dyslexia is based on the premise that individuals with the disorder have impaired sensitivity to rapidly changing stimuli in the visual and auditory modalities, due to a dysfunction in the magnocellular channel of the visual system and its analogue in the auditory pathway. The deficit in the auditory system is thought to cause difficulties in the segmentation of speech and the formation of accurate phonological representations, leading to problems in making the grapheme-phoneme correspondences necessary for reading. In a sample of 13 adults with a history of severe reading difficulty and 18 controls, visual contrast thresholds were measured in response to an 8-Hz flickering Gaussian blob as well as a slowly modulated 8 cycles/deg Gaussian windowed grating. Auditory thresholds were measured in response to a 4-s burst of white noise, the 2nd or 3rd second of which was amplitude modulated at 100 Hz or 1 Hz. The adult reading difficulty group exhibited normal thresholds to rapidly changing stimuli in both modalities and to the slowly modulated visual stimulus, but some showed reduced sensitivity to the 1-Hz amplitude-modulated auditory stimulus. Sensitivity to amplitude modulation at slower rates has been shown to be important for segmentation of the speech stream and so may be implicated in the reading difficulty of the affected individuals. A magnocellular deficit cannot explain this impaired sensitivity, which may be the result of a reduced echoic memory span.

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The influence of color on transient system activity: Implications for dyslexia research

Cited by 16 publications

References 53 publications

The effects of red surrounds on visual magnocellular and parvocellular cortical processing and perception

The effects of red surrounds on visual magnocellular and parvocellular cortical processing and perception

Inhibition of vection by red

A test of the magnocellular deficit theory of dyslexia in an adult sample

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