PrePrint Version (Edgcumbe, 2020): The developmental trajectory of open-mindedness: from 18 to 87-years of age.

Objectives: The present study examined the role of aging in participants between 18 and 87-years of age on open-mindedness in the Actively Open-minded Thinking (AOT) scale and the Actively Open-minded Thinking about Evidence (AOT-E) scale. Method: The amalgamated data from 12 Amazon Mechanical Turk™ studies was analysed. This included a total of 9010 participants (age: M = 37.30, SD = 14.13 / sex: 4191 males, 4734 females and 85 who did not wish to state their sex). All participants completed the 7-item Actively Open-minded Thinking (AOT) scale, of these participants four-hundred and ninety-one also completed the 8-item Actively Open-minded Thinking about Evidence (AOT-E) scale (age: M = 33.27, SD = 5.78 / sex: 2317 males, 2512 females and 62 who did not wish to state their sex). Results: AOT score positively correlated with AOT-E score (r = 0.27). Age negatively correlated with AOT score (r = -0.11) and AOT-E score (r = -0.13). There was a statistical difference in AOT score between the age ranges of participants (18-28, 29-38, 39-48, 49-58, 59-68 and 69-87 years of age). There was also a difference in AOT-E score between the age ranges of participants too. Discussion: The results showed that open-mindedness as measured by the AOT and AOT-E decreased as a function of aging. In an aging population were more adults work into later age the decrease in open-mindedness could influence many areas of judgments of decision-making.