Volume 2 – From Birth to 29 Months

Number 7 – Intraindividual Change in Behaviour from 17 to 29 Months

Certain behavioural problems characteristic of children said to be "having difficulty" are relatively widespread in the general population of children of pre-school age. These behaviours are transitory for most children, and are associated with certain ages. However, for some, they constitute the first signs of problems that will appear later when they enter the school system. This paper documents a number of these behaviours - opposition-defiance, inattention, hyperactivity, physical aggression toward peers, unself-reliance, timidity-shyness and prosociality. First, the prevalence of each of these behaviours in children 17 and 29 months of age is described, as is their variation by sex. Second, individual changes in these behaviours are examined at both ages, to determine whether, for each behaviour, 1) the degree it presented at 17 months is related to the degree it presented at 29 months, and 2) the majority of children who frequently presented it at 17 months continued to do so at 29 months, namely a year later.