Conscientiousness is the state of being thorough, careful, or vigilant; it implies a desire to do a task well. Conscientiousness is also one trait of the five-factor model of personality, and is manifested in characteristic behaviors such as being efficient, organized, neat, and systematic. It includes such elements as self-discipline, carefulness, thoroughness, self-organization, deliberation (the tendency to think carefully before acting), and need for achievement. It is an aspect of what has traditionally been called character. Conscientious individuals are generally hard working and reliable. When taken to an extreme, they may also be "workaholics", perfectionists, and compulsive in their behavior. People who score low on conscientiousness tend to be more laid-back, less goal-oriented, and less driven by success; they also are more likely engage in antisocial and criminal behavior.
Personality models 
Conscientiousness is one of five superordinate traits in the "Big Five model" of personality, which also consists of extraversion, neuroticism, openness to experience, and agreeableness. Two personality tests that assess these traits are Costa and McCrae's NEO PI-R and Goldberg's NEO-IPIP. According to these models, conscientiousness is considered to be a continuous dimension of personality, rather than a categorical "type" of person. Scores on conscientiousness follow a normal distribution.
Conscientiousness is related to impulse control, but it should not be confused with the problems of impulse control associated with other personality traits, such as (high) extraversion, (low) agreeableness, (high) openness and (high) neuroticism. Individuals low on conscientious are unable to motivate themselves to perform a task that they would like to accomplish. Recently, conscientiousness has been broken down, further, into two "aspects": orderliness and industriousness, the former which is associated with the desire to keep things organized and tidy and the latter which is associated more closely with productivity and work ethic. Conscientiousness, along with (lower) openness, is also one of the trait markers of political conservatism.
The trait cluster of conscientiousness overlaps with other models of personality, such as C. Robert Cloninger's Temperament and Character Inventory, in which it is related to both self-directedness and persistence. It also includes the specific traits of rule consciousness and perfectionism in Cattell's 16 PF model. It is negatively associated with impulsive sensation-seeking in Zuckerman's alternative five model. Traits associated with conscientiousness are frequently assessed by self-report integrity tests given by various corporations to prospective employees.
Extent of conscientiousness is generally assessed using self-report measures, although peer-reports and third-party observation can also be used. Self-report measures are either lexical or based on statements. Deciding which measure of either type to use in research is determined by an assessment of psychometric properties and the time and space constraints of the study being undertaken.
Lexical measures use individual adjectives that reflect conscientiousness traits, such as efficient and systematic, and are very space and time efficient for research purposes. Goldberg (1992) developed a 20-word measure as part of his 100-word Big Five markers. Saucier (1994) developed a briefer 8-word measure as part of his 40-word mini-markers. Thompson (2008)  systematically revised these measures to develop the International English Mini-Markers which has superior validity and reliability in populations both within and outside North America. Internal consistency reliability of the International English Mini-Markers for the Conscientiousness measure for native English-speakers is reported as .90, that for non-native English-speakers is .86.
Statement measures tend to comprise more words than lexical measures, so hence consume more research instrument space and more respondent time to complete. Respondents are asked the extent to which they, for example, Often forget to put things back in their proper place, or Am careful to avoid making mistakes. Some statement-based measures of conscientiousness have similarly acceptable psychometric properties in North American populations to lexical measures, but their generally emic development makes them less suited to use in other populations. For instance, statements in colloquial North American English like Often forget to put things back in their proper place or Am careful to avoid making mistakes can be hard for non-native English-speakers to understand, suggesting internationally validated measures might be more appropriate for research conducted with non-North Americans.
People who score high on the trait of conscientiousness tend to be more organized and less cluttered in their homes and offices. For example, their books tend to be neatly shelved in alphabetical order, or categorized by topic, rather than scattered around the room. Their clothes tend to be folded and arranged in drawers or closets instead of lying on the floor. The presence of planners and to-do lists are also signs of conscientiousness. Their homes tend to have better lighting than the homes of people who score low on this trait. Recently, ten behaviors strongly associated with conscientiousness were scientifically categorized (the number at the end of each behavior is a correlation coefficient; a negative number means conscientious people were less likely to manifest the behavior):
- Discussed sexual matters with a male friend (−.23)
- Lounged around my house without any clothes on (−.22)
- Picked up a hitch-hiker (−.21)
- Read a tabloid paper (−.19)
- Drove or rode in a car without a seatbelt (−.19)
- Swore around other people (−.18)
- Spent an hour at a time daydreaming (−.18)
- Shopped at a second-hand thrift shop (−.18)
- Told a dirty joke (−.18)
- Listened to music (+.18)
Academic and workplace performance 
Conscientiousness is importantly related to successful academic performance in students and workplace performance among managers and workers. Low levels of conscientiousness are strongly associated with procrastination. A considerable amount of research indicates that conscientiousness is one of the best predictors of performance in the workplace, and indeed that after general mental ability is taken into account, the other four of the Big Five personality traits do not aid in predicting career success.:169 Conscientious employees are generally more reliable, more motivated, and harder working. They also have lower rates of absenteeism and counterproductive work behaviors such as stealing and fighting with other employees. Furthermore, conscientiousness is the only personality trait that correlates with performance across all categories of jobs. However, agreeableness and emotional stability may also be important, particularly in jobs that involve a significant amount of social interaction.
Subjective well-being 
In general, conscientiousness has a positive relationship with subjective well-being, particularly satisfaction with life, so highly conscientious people tend to be happier with their lives than those who score low on this trait. Although conscientiousness is generally seen as a positive trait to possess, recent research has suggested that in some situations it may be harmful for well-being. In a prospective study of 9570 individuals over four years, highly conscientiousness people suffered more than twice as much if they became unemployed. The authors suggested this may be due to conscientious people making different attributions about why they became unemployed, or through experiencing stronger reactions following failure. This finding is consistent with perspectives which see no trait as inherently positive or negative, but rather the consequences of the trait being dependant on the situation and concomitant goals and motivations.
Problematic life outcomes 
Low conscientiousness has been linked to antisocial and criminal behaviors, as well as unemployment, homelessness, and imprisonment. Low conscientiousness and low agreeableness taken together are also associated with substance abuse. People low in conscientiousness have difficulty saving money and have different borrowing practices from more conscientious people. High conscientiousness is associated with more careful planning of shopping trips and less impulse buying of unneeded items.
Health and longevity 
According to an 80-year old and ongoing research started in 1921 by psychologist Lewis Terman on over 1,500 ten-year-old Californians, "The strongest predictor of long life was conscientiousness." Specific behaviors associated with low conscientiousness may explain its influence on longevity. Nine different behaviors that are among the leading causes of mortality - alcohol use, disordered eating (including obesity), drug use, lack of exercise, risky sexual behavior, risky driving, tobacco use, suicide, and violence - are all predicted by low conscientiousness. Health behaviors are more strongly correlated with the conventionality rather than the impulse control aspect of conscientiousness. Apparently, social norms influence many health-relevant behavior, such as healthy diet and exercise, not smoking and moderate drinking, and highly conscientiousness people adhere the most strongly to these norms. Additionally, conscientiousness is positively related to health behaviors such as regular visits to a doctor, checking smoke alarms, and adherence to medication regimes. Such behavior may better safeguard health and prevent disease.
Relationship quality is positively associated with partners' level of conscientiousness, and highly conscientious people are less likely to get divorced. Conscientiousness is associated with lower rates of behavior associated with divorce, such as extramarital affairs, spousal abuse, and alcohol abuse. Conscientious behaviors may have a direct influence on relationship quality, as people low in conscientiousness are less responsible, less responsive to their partners, are more condescending, and less likely to hold back offensive comments. On the other hand, more conscientious people are better at managing conflict and tend to provoke fewer disagreements, perhaps because they elicit less criticism due to their well-controlled and responsible behavior.
Average levels of conscientiousness vary by state in the United States. People living in the central part of the country, including the states of Kansas, Nebraska, Oklahoma, and Missouri tend to have higher scores on average than people living in other regions. People in the southwestern states of New Mexico, Utah, and Arizona also have relatively high average scores on conscientiousness. Among the eastern states, Florida is the only one that scores in the top ten for this personality trait. The four states with the lowest scores on conscientiousness on average were, in descending order, Rhode Island, Hawaii, Maine, and Alaska.
See also 
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- Costa, P. T. & McCrae, R. R. (1992). NEO personality Inventory professional manual. Odessa, FL: Psychological Assessment Resources.
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- Goldberg, L.R.; Johnson, JA; Eber, HW; et al (2006). "The international personality item pool and the future of public-domain personality measures". Journal of Research in Personality 40 (1): 84–96.
- Goldberg, L.R. (1992). "The development of markers for the Big-Five factor structure". Psychological Assessment 4 (1): 26.
- Saucier, G (1994). "Mini-Markers – a brief version of Goldberg’s unipolar big-five markers". Journal of Personality Assessment 63 (3): 506–516.
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- Roberts, B.W.; Jackson, J.J.; Fayard, J.V.; Edmonds, G. & Meints, J (2009). "Chapter 25. Conscientiousness". In Mark R. Leary, & Rick H. Hoyle. Handbook of Individual Differences in Social Behavior. New York/London: The Guildford Press. pp. 257–273. ISBN 978-1-59385-647-2.
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- Boyce, C. J., & Wood, A., M., & Brown, G. D. A. (in press). The dark side of conscientiousness: Conscientious people experience greater drops in life satisfaction following unemployment.Journal of Research in Personality
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- Walton, KE, Roberts, BW. (2004). "On the relationship between substance use and personality traits: abstainers are not maladjusted". J. Res. Personal 38: 515–35.
- "Psychological Predictors of Long Life: An 80-year study discovers traits that help people to live longer.". Psychology Today. June 5, 2012.
- Stephanie Simon (2008-09-23). "The United States of Mind. Researchers Identify Regional Personality Traits Across America". WSJ.com. Original research article: Peter J. Rentfrow, Samuel D. Gosling and Jeff Potter (2008). "A Theory of the Emergence, Persistence, and Expression of Geographic Variation in Psychological Characteristics". Perspectives on Psychological Science 3 (5): 339–369. doi:10.1111/j.1745-6924.2008.00084.x.