A cognitive disability has been defined as the deficiency of neuropsychological functions related to degeneration or injury within a specific area of the brain, a slower than normal rate in cognitive developmental maturation, or delayed cognitive processes.
The Australian Emergency Management Institute also defines it as a disability that affects a person’s ability to process information. This may be due to an intellectual disability a person was born with or acquired through a brain injury (i.e. a stroke, or head injury). It may also be caused by alcoholism, depression, Alzheimer’s, some psychiatric conditions, Parkinson’s disease, and chronic fatigue syndrome. People with cognitive impairment or learning disability will vary greatly in their abilities and needs.  Those building occupants will have an inability to process the evacuation information which will result in decreased ability, and a potential time delay, to process or understand the information and cues received by their senses.
 International Organisation of Standardization 2011, International Standard ISO 21542 Building construction – Accessibility and usability of the built environment, 1st edn, ISO Copyright office, Switzerland, p.5
 Australian Emergency Management Institute 2013, Communicating with People with Disability: National Guidelines for Emergency Managers Handbook 5, http://www.em.gov.au/Publications/Australianemergencymanualseries/Documents/CommunicatingwithPeoplewithDisabilityNationalGuidelinesforEmergencyManagers.PDF, viewed 20 May 2014
 National Fire Protection Association 2007, Emergency Evacuation Planning Guide for People with Disabilities, NFPA, Massachusetts, p.11