The effects of ageing on self-reported aggression measures are partly explained by response bias.

BACKGROUND Recent studies have suggested that the age-personality relationship may be partly explained by age-related changes in response bias. In the present study, we analysed how age affected social desirability and acquiescence, and how this effect impacted the age-aggression relationship. METHOD We used the Indirect-Direct Aggression Questionnaire, which provides response bias and physical, verbal and indirect aggression scores independently of each other. We applied this test to a sample of 616 individuals aged between 18 and 96 (M = 49.24, SD = 24.81) and analysed the relationships between age and aggression measures with and without response bias. RESULTS We found that social desirability and acquiescence increased by between one and two standard deviations between adulthood and old age. This affected the age-aggression relationship for all aggression scales and, especially for verbal and indirect aggression, whose relationships with age decreased from r = -.192 and r = -.309 to r = .012 and r = -.159, respectively, when response biases were controlled. CONCLUSIONS When response bias and, in particular social desirability, are not controlled, elderly people tend to show aggression scores that are considerably lower than their true aggression levels.