From very early in life, humans can approximate the number and surface area of objects in a scene. The ability to discriminate between 2 approximate quantities, whether number or area, critically depends on the ratio between the quantities, with the most difficult ratio that a participant can reliably discriminate known as the Weber fraction.…

Visual persistence was investigated in adults with and without dyslexia in order to determine whether dyslexic adults demonstrate problems similar to those found in childhood dyslexia. Results showed that sensitivity of dyslexic adults was impaired when parts of a test stimulus were presented to adjacent retinal areas, suggesting that under…