Flicker or Pattern Sensitivity (2A)
Flicker or pattern sensitivity is a student's physiological response to a rapid switching back and forth of visual stimuli from high to low brightness or shifting patterns.
Students with flicker or pattern sensitivity have a physiological reaction to repetitive patterns, flickering video, or stroboscopic lights. Depending on the specific disability, the student's reaction might take the form of a seizure, pain, or visual overload. A flicker rate of 15 - 20 Hz is considered to be the most likely to trigger a physiological response. Flicker at or above 60 Hz are relatively safe as are very low rates, although seizures have been triggered at as few as 3 Hz.
Students with flicker or pattern sensitivity have a physiological reaction to repetitive patterns, flickering video, or stroboscopic lights. Depending on the specific disability, the student's reaction might take the form of a seizure, pain, or visual overload. A flicker rate of 15 - 20 Hz is considered to be the most likely to trigger a physiological response. Flicker at or above 60 Hz are relatively safe as are very low rates, although seizures have been triggered at as few as 3 Hz.
Formal Diagnostics
- Diagnosis of photosensitive epilepsy
- Diagnostic information referring to sensitivity to pattern or flicker.
Intake Questions
- When you see flashing lights or fast moving video do you become queasy or have a seizure?
- Do complicated patterns such as optical illusions make you feel like you are motion sick?
- Do quickly moving objects like fans or shadows from trees make you feel disoriented or off-balance?
- What accommodations or strategies have been effective in the past?
Resources
- American Epilepsy Society
http://www.aesnet.org/ - Epilepsy Foundation of America
http://www.epilepsyfoundation.org/ - WCAG 2.0 Flash Guidelines
http://www.w3.org/TR/WCAG20/#general-thresholddef - Canadian Epilepsy Alliance
http://www.epilepsymatters.com/english/faqphotosensitive.html - TRACE Photosensitive Epilepsy Analysis Tool
http://trace.wisc.edu/peat/
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