Age-Related Differences in Naming Latency Variability.

Variability in naming latencies is expected to increase with age on multiple levels, but few studies have examined whether this is indeed the case. In the present study, we tested whether performance variability increases with age by comparing young and older adults in the amount of naming latency variability between participants, across items, and within participants across trials and days. We additionally used estimates of performance variability for power analyses to determine how samples (i.e., participants/items) should be adjusted to achieve sufficient power in studies comparing latencies across age groups. We tested older adults (aged 65-75) on two occasions (7-16 days apart) and compared their naming latencies with those of young adults (aged 18-35) tested in another study using the same procedures. We replicated the age-related slowing in naming latencies reported by some authors. We found greater between-item variability in older participants, no evidence for or against an age-related increase in between-participant variability, and evidence for no increases in participant variability across trials with age. Moreover, variability across days was greater in the young than the older adult group. We discuss the relevance of these findings for designing future studies as well as for better understanding mixed findings in past studies.