Baby boomers and millennials form two major user groups that tend to exhibit different behaviors when viewing online information. Because important online information is often communicated via text, understanding the differences in the way textual information is scanned by these two user groups allow designers to better meet the needs of each group. Our results showed that saccadic amplitudes were strong predictor of user age groups when they were reading a relatively long and difficult text passage. These results help to improve online reading experience by examining metrics that can unobtrusively capture and compare the overall reading experience of younger and older users. The results are also relevant to research in designing advanced decision tools that use eye tracking to detect cognitive effort to respond to user needs.