ABSTRACT
There may be a wide variation in the abilities and behaviour of mentally subnormal people, even when they are superficially similar in appearance and of apparently similar I.Q. Those with the most profound degrees of amentia remain completely dependent throughout their lives, lying in bed and showing no obvious awareness of their environment and no purposeful activity. They never speak and show no sign of understanding what is said to them and make little response to attempts to stimulate them. They have to be washed, dressed and fed and never acquire any control of their bowels or bladder. With less severe degrees of amentia, spontaneous activity and understanding increase, as do the response to training and the ability for self-care. In those with moderate degrees of amentia, academic abilities are limited and although their rote memory may be good and they may be able to count and read in a mechanical manner, they are usually unable to do any but the simplest calculations and do not have the reasoning ability necessary for leading an independent life. However, they may show surprising islands of above-average ability, for example in music and art, or, as in several well known cases, in arithmetical ability (the so-called idiots savants), completely out of keeping with their otherwise obvious mental subnormality. With training, those with moderate degrees of amentia should be capable of carrying out simple repetitive tasks, at which they will continue for long periods at a steady pace. Those with still less severe degrees of amentia are likely to be capable of unskilled or semi-skilled employment, although they may need constant supervision because of their poor powers of concentration and their greater capacity for being distracted by events around them. On the other hand, many people with a mild mental handicap are able to hold down regular jobs in the community in competition with people of higher intelligence.
