Penny Galbraith

Mainstreaming visual contrast in built, transport and information environments for everyone, everywhere, everyday

Presenter: Penny Galbraith. GalbraithScott

Oral presentation

Vision is our dominant sense and is the process of deriving meaning from what is seen.  Half the human brain is devoted directly or indirectly to vision (MIT, 1996).  In the brain, visual processing accounts for about 30% of the cortex, compared with 8% for touch and 3% for hearing (Seyens, 2019).  About 80% percent of our perception, learning, cognition, and activities are mediated through vision.  The visual process generates appropriate motor, and/or cognitive responses to the world around us (Brainline, 2019).  This is why people with an acquired brain injury often have a vision impairment.

Visual contrast sensitivity is a crucial part of human vision (different to acuity) allowing detection of objects and discriminating objects or details from their background.  Poor visual contrast therefore has a very significant impact on people with a vision impairment.

Worldwide, luminance contrast has been recognised in Standards and Codes for new buildings, transport and information, as the most relevant measure of how a person visually perceives their environment. Luminance contrast is recognised as crucial for safety and is vital to remove environmental barriers for people with a vision impairment.  However, luminance contrast is a tiny fraction of compliance and neglected in maintenance of existing assets.

Prescribed measuring techniques involve expensive, bulky equipment which is a barrier to use and controlled light source measurements do not reflect ambient lighting, or how an environment is experienced by users. The consequence is that new facilities often fail to achieve acceptable luminance contrast outcomes.  In existing buildings, public spaces and transport, luminance contrast requires maintaining as surfaces become damaged and dirty.

This paper describes human vision in more detail and why providing luminance contrast is so important to universal design and to removing environmental barriers.  The paper will also propose a new research-based approach to measure luminance contrast to make it a mainstream concern for everyone, everywhere, everyday.