A study examined the age-related differences in impersonal (objective) and personal (subjective) styles of thinking and the influences these differences have on traditional cognitive measures. Data were obtained from two 2-hour interviews with 333 participants in their homes, at senior centers, or on a university campus. All participants were given a battery of measures of memory, problem solving, fluid and crystallized intelligence, and affective functioning. Participants were classified as young adults (17-22 years); middle-aged adults (40-50 years); old adults (60-70); and old-old adults (75-99 years). Participants' responses were scored on a variety of dimensions, included the divisions of "intrapersonal,""within family,""interpersonal,""impersonal," and "other." A multivariate analysis of variance (MANOVA) revealed significant age-related differences in the frequency of division types. Intrapersonal divisions were significantly more frequent in old and old-old adults than in young adults, whereas interpersonal divisions were significantly more frequent in young adults. Consistent with previous research, the sample demonstrated the "classic aging pattern" in cognitive performance. The older adults were more likely to use an intrapersonal type of reasoning, whereas the young adults displayed more abstract reasoning. The study observed that various patterns of thinking were also found within age groups, leading to the conclusion that styles of thinking may reflect age but are not limited to age. (33 references) (KC)