English

Abstract

Introduction Unusual responses to sensory stimuli were noticed from the very beginning of the official history of autism, and the pioneering research started in the 1960s; since then for many decades, sensory hypotheses were not considered important because there were no empirical evidence for this assumption. At present, however, we witness an explosion of interest in sensory perceptual issues, and the sensory perceptual theory of autism is steadily taking shape, incorporating findings from other related fields and producing a framework for studying sensory differences in autism and their impact not only on behaviours but also on language, cognition and social impairments of individuals with autism spectrum disorder. As a review of all the available literature is beyond the scope of this paper, only a selection of research studies relevant to some methodological and conceptual problems of sensory perception in autism is included. This review challenges the conventional interpretation that gives primacy to social communication problems. The recognition of sensory perceptual differences in autism can assist in improving diagnostic instruments and provide information about appropriate support for each individual. Conclusion Current research has aimed to explain sensory perceptual processes and their mechanisms, but there is no real understanding regarding sensory processing. We call on more research to be done on sensory processing in autism to improve our understanding and to actually be able to help individuals with autism correctly. Introduction First sensory hypotheses Unusual responses to sensory stimuli were noticed from the very beginning of the official history of autism. Both Kanner1 and Asperger2 described bizarre reactions of their patients to sound, touch, sights, taste and smell. Based on their clinical observations, Bergman and Escalona3 put forward a sensory hypothesis to explain the development of autism: autistic children start life with a higher degree of sensory sensitivity, which makes them acquire defensive strategies to protect themselves from overload, which, in turn, results in developmental distortions that are reflected in autistic conditions. Eveloff4 described severe perceptual difficulties encountered by children with autism. Creak5 included unusual sensory perceptual experiences in the list of core symptoms of autism. Rimland6 emphasized the importance of exploring perceptual abilities of autistic children. Lorna Wing7 showed that autistic children have significantly more sensory perceptual problems than both typically developing children and children with Down’s syndrome and included sensory perceptual features into ‘basic impairments in autism’. Ornitz8 researched disorders of perception common in autism and extended the notion of a disorder of sensory processing to the notion of sensory and information processing. This approach allowed him to clarify and identify separate stages and functions of sensory perception and consider information processing in terms of more discrete functions, such as attention, memory and learning9. It was suggested that autism might be identified in young children if we look at very specific and easily described behaviours caused by sensory perceptual differences. For example, before the age of 6, these behaviours were observed with almost the same frequencies as behaviours related to social and communication impairments10. Delacato11 hypothesized that unusual sensory experiences were a primary characteristic feature of autism, which were able to account for the basic symptoms of the condition considered to be essential in the diagnostic classifications. Thus, abnormal perceptions might give rise to high levels of anxiety; this, in turn, results in obsessive or compulsive behaviours, social and communication problems, making the more commonly accepted criteria, in fact, secondary developmental problems. Another strand of research has been carried out in the field of occupational therapy (OT). It was started by Ayres12 who formulated the theory of sensory integration (SI) dysfunction to describe a variety of neurological disorders. This theory attempted to account for the relationship between sensory processing and behavioural deficits in different developmental disorders including autism. Ayres originally limited her investigation to three senses—tactile, vestibular and proprioceptive—and identified the * Corresponding author: Email: bogdashina.kspu@mail.ru International Autism Institute at the KSPU, Russia 100, Marx Street, Krasnoyarsk, Russia, 660049