Students with ASDs are described as sharing a triad of impairments that affects their ability to understand and use non-verbal and verbal communication, understand social behaviour – which affects their ability to interact with other students and adults – and think and behave flexibly, which may be shown in restricted, obsessional or repetitive activities. This triad may be described as a tripartite cluster of specific abnormal patterns of social, communicative and thought behaviours. It has been suggested that an additional dimension related to difficulties in processing sensory information might also be added to the triad.
Impairments in communication refer to verbal and non-verbal communication. Verbal difficulties may include a delay in the development of language, comprehension difficulties, literalness, poorly modulated intonation and delivery of speech, echolalia (echoing speech), unusual vocabulary and repetitive use of language.
Non-verbal difficulties include difficulty in empathising with others and in appropriately interpreting social cues, body language and facial expressions. Gestures are often stiff, stilted or overexaggerated.
Students demonstrate a lack of flexibility of thinking and behaviour and one may notice poor social imagination, resistance to change, restricted and/or repetitive activities and routines, and an obsessional and narrow range of interests.
Symbolic play and joint attention skills are also impaired in students with ASDs. A lack of ‘shared attention’ or difficulty participating in the activities or enjoyment of others has been highlighted as a particular challenge to teachers as it affects the student’s ability to share interests, have varied interests, adapt behaviour according to the situation, accept changes in rules and routines, engage in imaginative play with others, accept others’ points of view and generalise learning.
Furthermore students with ASDs may engage in hand flapping, rocking or spinning; demonstrate heightened sensitivity to noise, smell, taste, touch or visual stimuli; experience erratic sleep patterns; display unusual eating habits; engage in self-injurious or aggressive or hyperactive behaviour; exhibit an unusual posture or gait and possess irrational fears or phobias.
Since the 1980s the idea has emerged of a spectrum which acknowledges the impact of both the range of general learning disability and level of ASDs for the student’s learning and teaching programmes.