Are there differences between disabled and normal readers in their processing of visual information
Disabled-normal reader comparisons have represented a major research approach to investigating the possible involvement of visual processing deficits in reading disabilities. Studies using this approach have normally tested the performance of disabled and normal readers on one or more tasks thought to be tapping some aspect of visual processing to determine whether the disabled readers have significantly more difficulty. Conclusions about whether or not there is evidence of visual processing differences between disabled and normal readers are mixed: Some researchers and theoreticians have contended that the evidence shows disabled readers do not differ from normal readers in their processing of visual information (e.g., Calfee, 1983; Stanovich, 1985; Vellutino, 1979, 1987), whereas others have concluded the contrary (e.g., Di Lollo, Hansen, & MacIntyre, 1983; Lovegrove, Martin, & Slaghuis, 1986; Willows, Kershner, & Corcos, 1986). The conclusion drawn may depend on the stage of processing under investigation.