Red signals are typically used to signify danger in a range of situations including train travel. Red signals must be clearly identified as different from yellow as the potential consequences of misjudging signal colour has serious safety consequences. A study by Professor Joanne Wood et al, from QUT’s School of Optometry and Vision Science, confirmed that small amounts of optical defocus, such as those experienced when looking through the intermediate corridor of progressive lens or with sub-optimal refractive correction, can cause such colour-misconceptions.
This project conducted an experimental evaluation to evaluate further whether prescription spectacles with progressive lenses might alter the perception of signal colours and also whether selected spectacles lens tints might also have an effect on signal colour perception. Data collection included site visits and specialised laboratory-based testing to address this question.
- Low levels of optical blur resulted in misperception of the red signal as yellow/orange
- Sunglass tints alone (including a yellow tint, blue-block anti-reflection tint and a grey tint) did not affect perception of the colour of the train signal, but the grey tint exacerbated the effects of blur
It is suggested that train drivers should have their eyes examined on a regular basis and that optometrists undertaking vision testing and dispensing optical corrections for train drivers should be informed of the potential colour misperception problem.
Funding / Grants
- Australasian Centre for Rail Innovation (2018 - 2019)