The Cardiff Acuity Tests are designed especially for the hard to test age group, 12 months to 30 months. It uses familiar pictures and a procedure in the form of a game to attract and keep the attention of young children. The test relies on the technique of “preferential looking” – that is, the observer simply notes the child’s eye movements to determine whether he or she can see the picture. Additionally, the Cardiff Acuity Tests are very useful for testing adults with a severe learning disability and those with reduced cognition or decreased consciousness.