Older adults, compared to younger adults, tend to demonstrate better memory for positive information compared to negative information, a phenomenon known as the "positivity effect". However, existing empirical studies have yielded limited and somewhat conflicting results regarding whether repeated testing increases the magnitude of the positivity effect or not. These inconsistencies might be due to methodological differences among prior studies, particularly in the length of the temporal delays between the recall tests. The goal of this dissertation study was to further examine whether the magnitude of the positivity effect in recall changes through repeated testing, and evaluate whether the effects of repeated testing on the positivity effect depend on the length of the temporal delay between the recall tests. To do so, younger adults (n = 171) and older adults (n = 185) were shown positive, negative, and neutral pictures during encoding. They then completed two memory recall tests under one of the three delay conditions: no delay, 7-minute delay or 48-hour delay between the two tests. Contrary to the typical findings in positivity effect research, in this study there were no age differences in recall performance; both younger and older adults recalled more negative than positive items, and this was true across both tests and across all delay conditions. One possible explanation for the absence of the positivity effect is that this study was administered online, where participants’ engagement and effort may be reduced due to the absence of experimenter supervision. Supporting this interpretation, there were no significant age differences in overall recall performance, and younger adults recalled numerically fewer items than older adults. The total recall performance seen in this study was also lower than what is typically observed in positivity effect studies conducted in lab settings. Although the positivity effect is generally considered to be a robust phenomenon, these findings suggest that it may not reliably emerge in all contexts. Future research should explore the factors that contribute to the emergence versus absence of the positivity effect, particularly in unsupervised or online settings.