Evidence for magnocellular involvement in the identification of flanked letters

Clinical Psychophysical Assessment of the ON- and OFF-Systems of the Magnocellular and Parvocellular Visual Pathways

“…Recently, an increasing number of studies have shown impairment in early-stage processing of visual information. This impairment is not only related to retina and eye diseases like glaucoma [17,21,[31][32][33] ambliopia and strabismus [34], melanoma-associated retinopathy [24,18,28], X-linked retinitis pigmentosa [26,35], congenital stationary night blindness [28], and neurological diseases as migraine [30] or Duchenne Muscular Dystrophy [29], but also to the neurocognitive or high-level of cortex processing disorders, such as schizophrenia [36,37], autism [38][39][40], working memory impairment [41] and dyslexia [25,[42][43][44][45].…”

Constructing isoluminant stimuli for word recognition research: A precautionary study

“…All stimuli were presented in red or green against a background of the opposing color (green and red, respectively), which filled the display screen. These colors are commonly used to study effects of chromaticity on word recognition (see, e.g., Allen et al, 2002;Chase et al, 2003;Floyd & Dain, 2000;Kempner et al, 1996;Legge et al, 1990;Ojanpää & Näsänen, 2003;Omtzigt et al, 2002;Travis et al, 1990). Two flicker rates were used: 16 Hz and 20 Hz.…”

“…This provides some evidence of M pathway involvement in word recognition. The findings of Chase, Ashourzadeh, Kelly, Monfette, and Kinsey (2003), who used single word stimuli, also suggest that the M pathway provides the dominant source of information for word recognition under normal contrast conditions (see also Allen et al, 2002;Floyd & Dain, 2000;Kempner, Aggarwala, Zemon, Gordon, Hainline, & Riddell, 1996;Lehky, 2000;Ojanpää & Näsänen, 2003;Omtzigt, Hendriks, & Kolk, 2002).…”

“…Some studies have used HFP (Floyd & Dain, 2000;Legge et al, 1990;Omtzigt et al, 2002), but each of these studies used stimuli in the HFP task that differed substantially from the stimuli used to assess word recognition. Specifically, Floyd and Dain (2000) used rectangles, Legge et al (1990) used squares, and Omtzigt et al (2002) used disks.…”

“…Some studies have used HFP (Floyd & Dain, 2000;Legge et al, 1990;Omtzigt et al, 2002), but each of these studies used stimuli in the HFP task that differed substantially from the stimuli used to assess word recognition. Specifically, Floyd and Dain (2000) used rectangles, Legge et al (1990) used squares, and Omtzigt et al (2002) used disks. 2 The precise effects of these mismatches on the assessment of word recognition performance in each of these studies is currently unknown, but the evidence available from psychophysical research suggests that the levels of isoluminance determined by the HFP tasks used in these studies was not appropriate for studying word recognition.…”