Assistive technology and tools 
for learning difficulties, migraines 
and other neurological differences 


What triggers the hyperexcitability of the visual cortex?


Many research studies have investigated just this – starting with research into the triggers for epilepsy, and then moving on to migraines. Every colour has a different wavelength and it appears that, for some individuals, certain wavelengths of colour trigger this overexcitement.Some of the wavelengths need to be softened with a specific colour filter to slowdown the wavelength of light. Often the application of this filter brings an immediate calming sensation and the trigger that was previously causing the stress now has little effect.



Triggers are grouped into three categories:


1. Patterns or stripes

The contrast of light to dark in some patterns or stripes can be particularly uncomfortable.  These patterns or stripes can be found in:

  • Text (white background to black printed text or computer screens) 
  • Man-made structures and equipment such as Venetian blinds or escalator stairs (made worse by the fact they are moving) 
  • Fabric patterns such as hounds tooth or black and white stripes or zigzags. 

2. Flicker

Not all flicker is picked up by the naked eye, some flicker is so quick that we don’t even notice it – or do we.  Scientific studies have proven that certain frequencies of flicker from light sources are not only triggering visual stress, but creating physiological and negative health effects as well.  Sources of flicker include:

  • Fluorescent lights 
  • LED Lights 
  • Computer screens 
  • Television 
  • Computer white boards 

3. Glare from light sources

Glare from reflection can often be avoided by moving the angle of the source, however, other sources of glare are not so easily reduced, for example:

  • Vehicle lights at night 
  • Reflection of lights on wet surfaces 
  • Shine on desks 
  • Reflection from walls, posters and windows in classrooms 


Note: anyone can experience visual stress if conditions are right