1. Introduction Results: Mediational Analyses Results: Zero-Order Correlations Method Presented at the 15 th Annual Meeting of the Society for Personality and Social Psychology Austin, TX February, 2014 Conscientiousness Mediates the Relationship Between Age and Time-of-Day Preference Ryan J. Walker, Zachary D. Kribs, Andrew N. Christopher, Oren R. Shewach, and Mareike B. Wieth Time-of-day preference relates to when a person is both physically and cognitively at their peek  People feel most alert, energetic, and capable The relationship between age and time-of-day preference has been well-established (Adan et al., 2012)  Less than ~12 yrs. = morning preference; ~12 – 20 yrs. = evening preference; greater than ~20 = increasing preference for morning Research on personality and time-of-day preference has found that conscientiousness is the best predictor of morningness (Tsaousis, 2010)  Findings on the remaining Big Five factors are more inconclusive There are established age differences in personality (Lucas & Donnellan, 2009)  For example, conscientiousness tends to increase with age o Major life tasks may facilitate these changes (e.g., building a career) Given the relations among these variables described above, is it possible that conscientiousness mediates the relationship between age and time-of-day preference? Hypothesis  Consistent with previous research, older participants should express a strong morning preference, and younger participants should express a strong evening preference  More importantly, conscientiousness should mediate the relationship between age and time-of-day preference Mediation  Bootstrapping analyses to test if the Big Five personality traits mediate the relationship between age and time-of-day preference 491 participants, ranging in age from 17 to 71 years (M = 32.45 yrs., SD = 15.29; 48% female)  223 students introductory psychology students (M = 18.7 yrs., SD = 1.1)  268 participants from StudyResponse (M = 45.3 yrs., SD = 11.2) Participants first completed Costa and McCrae’s (1992) 240-item NEO-PI-R measure of the Big Five personality factors  Factors: conscientiousness (α =.93), agreeableness (α =.90), extraversion (α =.92), openness to experience (α =.91), neuroticism (α =.93)  Responses were made using a 1 (not at all descriptive of me) to 7 (very descriptive of me) range  48 items were averaged to form a score for each Big Five Factor Participants then completed Horne and Ostberg’s (1976) Morningness-Eveningness Questionnaire (MEQ), α =.83  Most common measure of time-of-day preference (Adan et al., 2012)  Example item: During the first half hour after having awakened in the morning, how tired do you feel? o Response options: very tired, fairly tired, fairly refreshed, very refreshed o Higher scores = morning preference; lower scores = evening preference Results: Mediational Model Consistent with previous research, age was related to time-of- day preference (r =.41)  Older participants indicated a stronger morning preference, whereas younger participants indicated a stronger evening preference Age was significantly correlated with each Big Five factor, except for openness  Positively correlated with agreeableness (r =.22) and conscientiousness (r =.31)  Negatively correlated with neuroticism (r = -.33) and extraversion (r = -.25) Each personality factor was significantly correlated with time-of-day preference  People scoring high on agreeableness (r =.14) and conscientiousness (r =.31) expressed a morning preference  People scoring high on openness (r = -.11), neuroticism (r = -.22), and extraversion (r = -.10) expressed an evening preference Discussion Conducted bootstrapping analyses using Preacher and Hayes’ (2008) SPSS macro  5000 boot iterations and a 99% percentile confidence interval (CI)  Enables testing of individual mediators, as well as the effect each mediator has in combination with the others Total effect of age on time-of-day preference remained significant when Big Five mediators were added (direct effect of age on time-of- day preference =.2095, p <.001)  When mediating factors were added, the coefficient decreased, but remained significant  Total indirect effect was not significant (point estimate of.0555 and a 99% bootstrap percentile CI of -.0002 to.1075) Individual mediators  Conscientiousness, with a point estimate of.0373 and a 99% CI of.0087 to.0695 was a unique mediator  None of the other Big Five factors mediated the relationship Conscientiousness attenuated the relationship between age and time-of-day preference  Conscientiousness plays a role in the relationship between age and time- of-day preference Findings consistent with life course perspective of personality traits  Conscientiousness may increase as people begin their careers, when certain behaviors are expected (e.g., arriving at work on time) Limitation  No participants were under the age of 17 o Around age 12 or 13, individuals tend to shift from a morning preference to an evening preference (Adan et al., 2012) o Conscientiousness levels tend to be lower at this age (Marsh et al., 2013) o Together, these findings provide further evidence that conscientiousness mediates the relationship between age and time-of-day preference Future Direction  Conscientiousness as a potential moderator of the relationship between time-of-day preference and work shift adjustment (ease of adapting to non-preferred time of day) Implications and Conclusions  Older people’s morning preference and younger people’s evening preference were significantly attenuated by conscientiousness  It is crucial to examine how conscientiousness may play a role in behaviors associated with time-of-day preference Contact Information Ryan Walker: walkerrj@miamioh.edu Andrew Christopher: achristopher@albion.edu