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.…

This review of literature on the aging process points out primary physiological and psychological changes in maturing adults which have implications for teachers of adults. Visual acuity and hearing decline during adult years and there is a general slowing down process of most bodily activities. Teachers should be aware of the need for good…