The results of the study related to involuntary response to preferred and indiff erent stimuli in children of the third year of life with autism spectrum disorder (ASD) and children without autism are presented. The research involved three children with ASD and three with delayed speech development, who do not have ASD, at the age of 2 years 2 months - 2 years 3 months. The study was conducted by observation, and the topography of the behavioural response in a child with ASD was determined: changes in facial expressions, movement speed, hand grip of an object, touching an object. In the course of the study, an intervention was carried out aimed at forming an involuntary response to environmental stimuli. In the conclusion of the work, the results of the intervention are described.