Driving is an important skill to support independence during aging. However, driving ability is vulnerable to decline as cognition worsens during the normative aging process. The primacy effect has been found to predict future cognitive decline and precede challenges completing functional activities of daily living. Thus, we examined whether the primacy effect relates to a common measure of driving ability used in driving capacity evaluations: Useful Field of View (UFOV). We also examined age as a moderator of the relationship between driving ability and primacy scores, given that both driving ability and cognition are susceptible to changes during aging.

Sixty-four participants were included from an archived deidentified database of older adults over age 60 from a rural region in the Midwest who participated in a driving study. The mean age was 71.38 years (Range=60–88) and the sample was comprised mostly of women (64.1%), was primarily white (98% white; 2% African American), and was well educated (mean=16.69 years). The primacy effect was derived from the first three items on the RBANS list learning task (higher values indicating higher primacy scores). Driving ability was measured with the UFOV crash risk score (measured from 1 to 5). Driving experience was defined as the self-reported number of years spent driving.

There were significant correlations between UFOV risk and age (r=.576, p<.001) and years of driving experiences (r=.483, p<.001). As expected, there was a high correlation between driving experience and age (r=.921, p<.001). Primacy did not correlate with any demographic variables. There was a small correlation between primacy and UFOV risk (r=-.260, p=.038).

A hierarchical linear regression was conducted with age in the first block, primacy in the second block, and UFOV risk as the dependent variable. In the final model, age was significantly predictive of UFOV risk, with higher age associated with higher risk, β=.018, t(61)=6.446, p<.001, but primacy was not significant, β=.055, t(61)=1.193, p=.237. However, there was a significant interaction between age and primacy on UFOV risk (B=0.119, F(2,61)=4.55, p=.037). Approximately 75 years of age represented a transition point such that there was a non-significant relationship between primacy and UFOV crash risk at this age (74.96; t(61)=2.0003, p=.05) or younger. However, for individuals over 74.96 years of age, there was a significant relationship between primacy and UFOV risk (t(61)=2.0066, p=.0493), with higher primacy scores relating to increased UFOV risk. Critically, the interaction remained significant even after accounting for driving experience; however, the point at which age became a moderator was slightly higher (76.4 years).

We identified a significant moderation of age on the relationship between primacy and UFOV crash risk such that a higher primacy score was only related to UFOV crash risk for those above 75 years of age. Continued investigation is required to expand the generalization of our findings to groups not represented in our sample. As our study was cross-sectional, future studies should examine whether the serial position effect has value in detecting individuals at risk for declines in driving skill over time.