"A state of arrested or incomplete development of mind "
Appears to include all people with a learning disability as long as it is caused before the mind is completely developed. Therefore this refers any person whose learning disability is a result of genetically caused disabilities, accident, disease or environment before or shortly after birth. It would not refer to someone for instance who has suffered a brain injury during adulthood.
"Severe impairment of intelligence"
The measurement of intelligenc is made using the IQ Test, an assessment using a battery of standardized tests to evaluate a person's ability to think and reason. It is not a measure of knowledge. The average IQ in the UK is about 100.
"Severe impairment of social functioning"
Refers to matters such as a person’s ability to manage the activities of daily living and generally look after themselves and cope accross all domains of their lives. It may also involve a consideration of the individual’s ability to relate meaningfully to other people.
Degrees of Learning Disability
Diagnosis requires that the assessor does not simply measure the young person's intelligence but takes into account the child's ability to function physically, socially, in activities of daily living and self care such as washing and dressing, as well as academically.
A commonly accepted measure of intelligence is IQ although there have also been controvesies about its application and validity in different populations. The categories below indicate the degrees of severity of learning disability
70-80 borderline learning disability
50 -70 mild learning disability
35 - 50 moderate learning disability
20 - 35 severe learning disability
Below 20 profound learning disability
But it's not all about IQ and cognition - people develop socially and emotionally with a rich variety of life experiences and relationships. Watch this video from the charity Mencap to hear from people with learning disabilities and their families discuss what a learning disability means to them.