Chronological age and crystallized intelligence of people with intellectual disability.

The influence of chronological age (CA) and fluid intelligence on the crystallized intelligence level of people with intellectual disability was studied in a group of 102 participants aged between 6 and 20 years. The results, which were based on their performance in 12 fluid and crystallized intelligence markers, indicate that the fluid intelligence factor and CA explain an important fraction of crystallized intelligence factor variance (43% and 21%, respectively). This finding provides support for the hypothesis that CA-related experience exerts a significant effect on the crystallized component of intelligence in people with intellectual disability.