Abstract: This study examined age differences and age-related changes in adults' primary cognitive abilities.Cross-sectional and longitudinal data were analyzed. The results indicated significant mean level declinein primary cognitive abilities. However, dissimilarities between different abilities were apparent in thetiming and rate of decline. Over a 3-year interval, wide individual differences became noticeable in thedirection and rate of change, and reliable decrement of most abilities appeared only in the group overage 60 or 70.

Key words: adult primary cognitive abilities, cross-sectional comparison, longitudinal analysis