<P> The Big Five personality traits have been assessed in some non-human species but methodology is debatable . In one series of studies, human ratings of chimpanzees using the Hominoid Personality Questionnaire, revealed factors of extraversion, conscientiousness and agreeableness--as well as an additional factor of dominance--across hundreds of chimpanzees in zoological parks, a large naturalistic sanctuary, and a research laboratory . Neuroticism and openness factors were found in an original zoo sample, but were not replicated in a new zoo sample or in other settings (perhaps reflecting the design of the CPQ). A study review found that markers for the three dimensions extraversion, neuroticism, and agreeableness were found most consistently across different species, followed by openness; only chimpanzees showed markers for conscientious behavior . </P> <P> Research on the Big Five, and personality in general, has focused primarily on individual differences in adulthood, rather than in childhood and adolescence, and often include temperament traits . Recently, there has been growing recognition of the need to study child and adolescent personality trait development in order to understand how traits develop and change throughout the lifespan . </P> <P> Recent studies have begun to explore the developmental origins and trajectories of the Big Five among children and adolescents, especially those that relate to temperament . Many researchers have sought to distinguish between personality and temperament . Temperament often refers to early behavioral and affective characteristics that are thought to be driven primarily by genes . Models of temperament often include four trait dimensions: surgency / sociability, negative emotionality, persistence / effortful control, and activity level . Some of these differences in temperament are evident at, if not before, birth . For example, both parents and researchers recognize that some newborn infants are peaceful and easily soothed while others are comparatively fussy and hard to calm . Unlike temperament, however, many researchers view the development of personality as gradually occurring throughout childhood . Contrary to some researchers who question whether children have stable personality traits, Big Five or otherwise, most researchers contend that there are significant psychological differences between children that are associated with relatively stable, distinct, and salient behavior patterns . </P> <P> The structure, manifestations, and development of the Big Five in childhood and adolescence has been studied using a variety of methods, including parent - and teacher - ratings, preadolescent and adolescent self - and peer - ratings, and observations of parent - child interactions . Results from these studies support the relative stability of personality traits across the human lifespan, at least from preschool age through adulthood . More specifically, research suggests that four of the Big Five--namely Extraversion, Neuroticism, Conscientiousness, and Agreeableness - reliably describe personality differences in childhood, adolescence, and adulthood . However, some evidence suggests that Openness may not be a fundamental, stable part of childhood personality . Although some researchers have found that Openness in children and adolescents relates to attributes such as creativity, curiosity, imagination, and intellect, many researchers have failed to find distinct individual differences in Openness in childhood and early adolescence . Potentially, Openness may (a) manifest in unique, currently unknown ways in childhood or (b) may only manifest as children develop socially and cognitively . Other studies have found evidence for all of the Big Five traits in childhood and adolescence as well as two other child - specific traits: Irritability and Activity . Despite these specific differences, the majority of findings suggest that personality traits--particularly Extraversion, Neuroticism, Conscientiousness, and Agreeableness - are evident in childhood and adolescence and are associated with distinct social - emotional patterns of behavior that are largely consistent with adult manifestations of those same personality traits . Some researchers have proposed the youth personality trait is best described by six trait dimensions: neuroticism, extroversion, openness to experience, agreeableness, conscientiousness, and activity . Despite some preliminary evidence for this "Little Six" model, research in this area has been delayed by a lack of available measures . </P>

Who came up with the five factor model of personality