<p>Despite the considerable influence of situational factors and the resulting variability in behavior, individuals maintain stable average ways of acting. The purpose of the studies presented in this paper was to investigate one possible explanation of this trait stability. It is hypothesized that contra-trait behaviors, those that are different from typical trait levels, demand more effort, or self-control, than do trait-typical behaviors. In Study 1, participants reported on the trait content of their behavior along with several other variables. In Study 2, participants completed several tasks in the lab and were instructed to act at contra-trait or trait-typical levels of conscientiousness. Support for the contra-trait effort hypothesis was found in Study 1: Participants reported that contra-trait behavior was more effortful than trait-typical behavior. In addition, habitual contra-trait behaviors, which do not require self-control, were exempt from this effect. In Study 2, no support was found for contra-trait hypotheses: Participants generally did not rate contra-trait behaviors as more effortful, and subsequent behaviors were not affected by contra-trait behaviors. The implications of the findings and the possible explanations of the non-findings are discussed.</p> / Dissertation

Very little is known about the effects of parental physical abuse on personality stability in adults. Thus, this study aimed to examine if parental physical abuse had an effect on personality stability over time above and beyond the effects of age and anxiety/depression. Furthermore, the study aimed to examine if gender differences could be found in personality stability even after controlling for the effects of parental physical abuse, age an anxiety/depression. The data used in the present study came from published datasets from the Midlife in the United States (MIDUS) studies and included a sample of 3,265 adults aged between 20 and 72 years at wave 1, 45.1% were males (M = 45.39, SD = 11.05) and 54.9% were females (M =45.36, SD = 11.27). Significant gender differences emerged in all of the Big Five personality traits. Parental physical abuse had no effect on any of the personality traits or their stability. Future research could take into consideration the limitations of this study in order to obtain better knowledge of the effects of physical abuse on personality stability. Practical implications regarding how therapy and social support affect the aftermath of abuse have been discussed.

Personlighet är per definition relativt stabila mönster av tankar, känslor och beteenden men det finns även klara belägg för att personlighet kan ändras under hela livsloppet. Exakt hur stabil personligheten är och vilka förändringar som sker hos äldre individer är däremot inte klarlagt. Mognadsprincipen säger att förändring i personlighetsdrag med ökad ålder speglar en funktionell mognad. Nyligen har det föreslagits att sådan mognad i personlighet hos de äldsta individerna skiljer sig från den förändring som sker hos unga vuxna och i medelåldern. Den föreliggande uppsatsen hade två syften. Det första var att undersöka rangordningsstabiliteten i personlighet hos äldre och det andra var att undersöka medelvärdesförändring i personlighetsdrag hos äldre utifrån mognadsprincipen. En longitudinell design användes i ett material av 341 individer mellan åldrarna 60–78 år vid baslinjemätning, över en tidsperiod av 12 år. Personlighet mättes med hjälp av femfaktormodellen (The Big Five). Resultaten visade att: (1) rangordningsstabiliteten var moderat till hög i alla fem personlighetsdrag, (2) Conscientiousness och Extraversion minskade för hela gruppen medan Agreeableness och Openness endast minskade för de yngre deltagarna, (3) Neuroticism visade en icke-signifikant trend av att öka hos de äldsta individerna. Uppsatsens resultat ger stöd för att personlighet är relativt stabil även bland äldre. De förändringar i personlighet som sker verkar skilja sig från trenderna som tidigare påvisats hos unga vuxna och i medelåldern och därmed spegla en annorlunda mognad. / Personality is by definition relatively stable patterns of thoughts, feelings and behaviour but there is also clear evidence that personality can change during the entire life span. Exactly how stable personality is and what kind of changes occur in the elderly, however, is not clear. The maturity principle states that change in personality traits with increased age reflects a functional maturity. Recently it has been proposed that such maturation of personality among the oldest individuals is different from the changes that happen in young adults and in middle age. The current study had two purposes. The first was to examine the rank-order stability of personality in the elderly and the second was to examine mean level change in personality based on the maturity principle. A longitudinal design was used in a sample of 341 individuals between the ages of 60-78 at baseline, over a time period of 12 years. Personality was measured using the five-factor model (The Big Five). The results showed that: (1) the rank-order stability was moderate to high in all five personality traits, (2) Conscientiousness and Extraversion decreased in the entire sample while Agreeableness and Openness decreased only in the younger participants, (3) Neuroticism showed a non-significant trend of increasing in the oldest participants. The results of the thesis support the notion that personality is relatively stable even among the elderly. The changes in personality that do occur seem to deviate from the trends that have been established in young adulthood and middle age and thereby reflect a different maturation.