Sarah M Haigh¹, Isabella M Durda²; ¹University of Nevada, Reno

Uncomfortable stripes can induce illusions, headaches, and seizures, but there is debate surrounding their effects on visual processing. Reading is a visually demanding task that can be slowed by increasing the horizontal autocorrelation of the text (more stripes within words) and by flickering light that induces a phantom array. Individuals who are visually sensitive are more affected by the flicker and stripes than those who are not. The current study investigated if the decline in reading speed was evident with other uncomfortable visual environments. We measured reading speed with text having high or low horizontal autocorrelation, and the text was surrounded by a chromatic grating pattern that varied in its component colors from one trial to the next. Grating patterns that contain large color differences (e.g. red/blue) tend to be more uncomfortable than patterns with a small color difference (e.g. pink/purple). The text comprised three- or four-letter words arranged in a random order to create a 15-line block of text. This reduced the effect of comprehension skills on reading speed and increased the visual demand, even for the low autocorrelation text. We also compared the reading speed of individuals with migraine (a visually sensitive group) with headache-free individuals. Reading speed was slower in the migraine group and slower when reading the high autocorrelation text compared to the low. There were small effects of color difference on reading speed, but these did not depend consistently on color difference. We conclude that uncomfortable visual environments can negatively affect visual processing but may depend on where they are presented in the visual field: the text was presented centrally and reliably affected reading whereas the surrounding chromatic gratings did not. The finding that the migraine group were slower overall highlights the visual demands involved in reading, supporting the need for visually comfortable text.

Acknowledgements: Nevada Undergraduate Research Award to IM Durda