Accidents are the major cause of childhood mortality and morbidity in industrialized societies. To devise effective programmes of accident prevention, it is necessary to obtain some estimate of young children's ability to perceive danger. Our study describes the abilities of children aged 3 to 6 years to perceive dangers commonly involved in childhood accidents—e.g. accidental falls, accidents involving scalds and burns, cuts and lacerations, electrocution, drowning, etc. Age effects, sex differences, and socio‐economic background effects are considered in the results of two studies, which ask children to identify and recognize dangerous situations.

Previous attempts to estimate developmental susceptibility to the horizontal‐vertical illusion have produced contradictory results. When susceptibility to the illusion is measured using a procedure appropriate to work with both adults and young children—namely, Pollack's rules for Taylor & Creelman's (1967) Parametric Estimation by Sequential Testing (PEST) procedure—it is found that susceptibility to the illusion does not significantly change in development from age three years to adulthood.