Ethological approach to autism spectrum disorders.

The purpose of the study was to develop a new ethogram for the assessment of children and adolescents with autism spectrum disorders (ASD) and intellectual developmental disorder (IDD) and to test whether this instrument accurately distinguishes ASD participants (n = 61) from IDD participants (n = 61). An ethogram with 88 behavior elements was generated, including body postures, verbalizations, facial expressions, motor stereotypies, head postures, gaze behavior, gestures, and interpersonal distance. Significant differences were detected between both groups in classic ASD behaviors; in behaviors that are deficient in ASD according to established theoretical models, such as symbolic play, gaze direction, gaze following, and use of mental state language; in atypical behaviors that have also been described previously in ethological studies with ASD; and in the nonspecific behaviors of ASD, such as walk, look own body, explore, and cry. The predictive success of a diagnosis of ASD in the logistic regression model with the ethogram's factors was 98.4%. The results suggest that this ethogram is a powerful and useful tool for both the detailed study of the social behaviors of autistic children and adolescents, and for discriminating ASD and IDD.