Trait theory

In psychology, trait theory (also called dispositional theory) is an approach to the study of human personality. Trait theorists are primarily interested in the measurement of traits, which can be defined as habitual patterns of behavior, thought, and emotion.^[1] According to this perspective, traits are aspects of personality that are relatively stable over time, differ across individuals (e.g. some people are outgoing whereas others are not), are relatively consistent over situations, and influence behaviour. Traits are in contrast to states, which are more transitory dispositions.

Some traits are something a person either has or does not have. In other traits, such as extraversion vs. introversion, each person is judged to lie along a spectrum.

Trait theory suggests that some natural behaviours may give someone an advantage in a position of leadership.^[2]

There are two approaches to define traits: as internal causal properties or as purely descriptive summaries. The internal causal definition states that traits influence our behaviours, leading us to do things in line with that trait. On the other hand, traits as descriptive summaries are descriptions of our actions that do not try to infer causality.^[3]

History

Gordon Allport was an early pioneer in the study of traits. This early work was viewed as the beginning of the modern psychological study of personality.^[4] He also referred to traits within his work as dispositions. In his approach, "cardinal" traits are those that dominate and shape a person's behavior; their ruling passions/obsessions, such as a need for money, fame etc. By contrast, "central" traits such as honesty are characteristics found in some degree in every person – and finally "secondary" traits are those seen only in certain circumstances (such as particular likes or dislikes that a very close friend may know), which are included to provide a complete picture of human complexity.^[5]

A wide variety of alternative theories and scales were later developed, including:

• Raymond Cattell's 16PF Questionnaire
• J. P. Guilford's Structure of Intellect
• Henry Murray's System of Needs
• Timothy Leary's Interpersonal circumplex
• Myers–Briggs Type Indicator
• Gray's Biopsychological theory of personality

Currently, two general approaches are the most popular:^{[citation needed]}

• Eysenck Personality Questionnaire, (EPQ) ("the three-factor model"). Using factor analysis Hans Eysenck suggested that personality is reducible to three major traits: neuroticism, extraversion, and psychoticism.^[6]
• Big Five personality traits, ("the five-factor model"). Many psychologists currently believe that five factors are sufficient: neuroticism, extraversion, openness to experience, agreeableness, and conscientiousness.^[7][8]

Trait theory in cross-cultural use

Cultures are widely known and accepted as being different in varying degrees. This can make the study of personality difficult as meaning and the expression of traits may be different within cultural groups. Trait theory uses a hierarchy of traits in order to separate culture from the traits; it can be said the culture is ignored in order to focus on the individual traits and how they are connected to the individual.^[9] Gordon Allport's trait theory not only served as a foundational approach within personality psychology, but also is continued to be viewed and discussed by other disciplines such as anthropology because of how he approached culture within trait theory.^[9]

Trait theory tends to focus on the individual over the situation in which they are in.^[10] This focus has relaxed within modern studies allowing for a consideration of the external factors outside of the self. As the focus becomes more relaxed (but still prominent as it is a main part of the theory) research expands.

Comparing EPQ and Big Five

Testing methodology, and factors

Both the EPQ and Big Five approaches extensively use self-report questionnaires. The factors are intended to be orthogonal (uncorrelated),^[11] though there are often small positive correlations between factors. The five factor model in particular has been criticized for losing the orthogonal structure between factors.^[12] Hans Eysenck has argued that fewer factors are superior to a larger number of partly related ones.^[13] Although these two approaches are comparable because of the use of factor analysis to construct hierarchical taxonomies, they differ in the organization and number of factors.

Whatever the causes, psychoticism marks the two approaches apart, as the five factor model contains no such trait. Moreover, psychoticism, unlike any of the other factors in either approach, does not fit a normal distribution curve. Indeed, scores are rarely high, thus skewing a normal distribution.^[14] However, when they are high, there is considerable overlap with psychiatric conditions such as antisocial and schizoid personality disorders. Similarly, high scorers on neuroticism are more susceptible to sleep and psychosomatic disorders.^[15] Five factor approaches can also predict future mental disorders.^[16]

Lower-order factors

Similarities between lower-order factors for psychoticism and the facets of openness, agreeableness, and conscientiousness (from Matthews, Deary & Whiteman, 2003)

There are two higher-order factors that both taxonomies clearly share: extraversion and neuroticism. Both approaches broadly accept that extraversion is associated with sociability and positive affect, whereas neuroticism is associated with emotional instability and negative affect.^[14]

Many lower-order factors, or facets, are similar between the two taxonomies. For instance, both approaches contain factors for sociability/gregariousness, for activity levels, and for assertiveness within the higher order factor extraversion. However, there are differences too. First, the three-factor approach contains nine lower-order factors and the five-factor approach has six.^[14]

Eysenck's psychoticism factor incorporates some of the polar opposites of the lower order factors of openness, agreeableness and conscientiousness. A high scorer on tough-mindedness in psychoticism would score low on tender-mindedness in agreeableness. Most of the differences between the taxonomies stem from the three factor model's emphasis on fewer high-order factors.

Causality

Although both major trait models are descriptive, only the three-factor model offers a detailed causal explanation. Eysenck suggests that different personality traits are caused by the properties of the brain, which themselves are the result of genetic factors.^[17] In particular, the three-factor model identifies the reticular system and the limbic system in the brain as key components that mediate cortical arousal and emotional responses respectively. Eysenck advocates that extraverts have low levels of cortical arousal and introverts have high levels, leading extraverts to seek out more stimulation from socializing and being venturesome.^[18] Moreover, Eysenck surmised that there would be an optimal level of arousal, after which inhibition would occur and that this would be different for each person.^[19]

In a similar vein, the three-factor approach theorizes that neuroticism is mediated by levels of arousal in the limbic system and that individual differences arise because of variable activation thresholds between people. Therefore, highly neurotic people when presented with minor stressors, will exceed this threshold, whereas people low in neuroticism will not exceed normal activation levels, even when presented with large stressors. By contrast, proponents of the five-factor approach assume a role of genetics^[8] and environment^[20] but offer no explicit causal explanation.

Given this emphasis on biology in the three-factor approach, it would be expected that the third trait, psychoticism, would have a similar explanation. However, the causal properties of this state are not well defined. Eysenck has suggested that psychoticism is related to testosterone levels and is an inverse function of the serotonergic system,^[21] but he later revised this, linking it instead to the dopaminergic system.^[22]

List of personality traits

After examining thousands of personality measures and numerous personality trait frameworks, researchers have created "super-frameworks" that aim to encapsulate all personality traits into a single model (e.g., Pan-Hierarchical Five Factor Model).^[23] These models also sometimes identify measures that can be used to measure traits/constructs in the models.^[24]

Other examples of personality traits

Openness to experience	Composed of two related but separable traits, Openness to Experience and Intellect. Behavioral aspects include having wide interests, and being imaginative and insightful, correlated with activity in the dorsolateral prefrontal cortex. Considered primarily a cognitive trait.[25]
Conscientiousness	Scrupulous, meticulous, principled behavior guided or conforming to one's own conscience. Associated with the dorsolateral prefrontal cortex.[26]
Extroversion	Gregarious, outgoing, sociable, projecting one's personality outward. The opposite of extroversion is introversion. Extroversion has shown to share certain genetic markers with substance abuse. Extroversion is associated with various regions of the prefrontal cortex and the amygdala.[27]
Agreeableness	Refers to a compliant, trusting, empathic, sympathetic, friendly and cooperative nature.[28]
Neuroticism	Identifies people who are prone to psychological distress. Individuals who are high in neuroticism tend to be anxious, depressed, self-conscious, impulsive, vulnerable and display angry hostility. "Neuroticism is the major factor of personality pathology."[29] Neuroticism has been linked to serotonin transporter (5-HTT) binding sites in the thalamus: as well as activity in the insular cortex.[30] Neuroticism also predicts the occurrence of more negative life experiences.[20]
Honesty-humility	Tendency towards sincerity, modesty, fairness, and greed avoidance. Those who score high on this trait feel little desire to manipulate others or to break the rules for personal gain.
Self-esteem (low)	A "favorable or unfavorable attitude toward oneself".[31] An individual's sense of his or her value or worth, or the extent to which a person values, approves of, appreciates, prizes, or likes him or herself".[32]
Harm avoidance	A tendency towards shyness, being fearful and uncertain, tendency to worry. Neonatal complications such as preterm birth have been shown to affect harm avoidance. People affected by eating disorders exhibit high levels of harm avoidance.[33] The volume of the left amygdala in girls was correlated to levels of HA, in separate studies HA was correlated with reduced grey matter volume in the orbitofrontal, occipital and parietal regions.[34]
Novelty seeking	Impulsive, exploratory, fickle, excitable, quick-tempered, and extravagant. Associated with addictive behavior.
Sensory processing sensitivity (SPS)	The defining trait of highly sensitive persons, characterized by the increased depth of processing of sensory input that underlies HSPs' greater proclivity to overstimulation, emotional reactivity and empathy, and sensitivity to stimuli.[35]
Perfectionism	"I don't think needing to be perfect is in any way adaptive." (Paul Hewitt, PhD)[36] Socially prescribed perfectionism – "believing that others will value you only if you are perfect." Self-oriented perfectionism – "an internally motivated desire to be perfect." Perfectionism is one of the traits associated with obsessional behavior and like obsessionality is also believed to be regulated by the basal ganglia.[37]
Alexithymia	The inability to express emotions. "To have no words for one's inner experience".[38] In studies done with stroke patients, alexithymia was found to be more prevalent in those who developed lesions in the right hemisphere following a cerebral infarction. There is a positive association with post-traumatic stress disorder (PTSD), childhood abuse and neglect and alexithymia. Utilizing psychometric testing and fMRI, studies showed positive response in the insula, posterior cingulate cortex (PCC), and thalamus.[39]
Rigidity	Inflexibility, difficulty making transitions, adherence to set patterns. Mental rigidity arises out of a deficit of the executive functions. Originally termed frontal lobe syndrome it is also referred to as dysexecutive syndrome and usually occurs as a result of damage to the frontal lobe. This may be due to physical damage, disease (such as Huntington's disease) or a hypoxic or anoxic insult.[40]
Impulsivity	Risk taking, lack of planning, and making up one's mind quickly.[41] A component of disinhibition. Abnormal patterns of impulsivity have been linked to lesions in the right inferior frontal gyrus and in studies done by Antonio Damasio author of Descartes' Error, damage to the ventromedial prefrontal cortex has been shown to cause a defect in real-life decision making in individuals with otherwise normal intellect. Those who sustain this type of damage are oblivious to the future consequences of their actions and live in the here and now.[42]
Disinhibition	Behavioral disinhibition is an inability or unwillingness to constrain impulses, it is a key component of executive functioning. Researchers have emphasized poor behavioral inhibition as the central impairment of ADHD. It may be symptomatic of orbitofrontal lobe syndrome, a subtype of frontal lobe syndrome which may be an acquired disorder as a result of traumatic brain injury, hypoxic ischemic encephalopathy (HIE), anoxic encephalopathy, degenerative diseases such as Parkinson's, bacterial or viral infections such as Lyme disease and neurosyphilis. Disinhibition has been consistently associated with substance abuse disorders, obesity, higher BMI, excessive eating, an increased rate of eating, and perceived hunger.[43]
Psychoticism	Psychoticism is a personality pattern typified by aggressiveness and interpersonal hostility, one of four traits in Hans Eysenck's model of personality. High levels of this trait were believed by Eysenck to be linked to increased vulnerability to psychosis such as schizophrenia. He also believed that blood relatives of psychotics would show high levels of this trait, suggesting a genetic basis to the trait.[44]
Obsessionality	Persistent, often unwelcome, and frequently disturbing ideas, thoughts, images or emotions, rumination, often inducing an anxious state. Obsessionality may result as a dysfunction of the basal ganglia.[45]

See also

• 16 Personality Factors – Self-report personality test
• Alternative five model of personality – personality model with five factors: impulsive sensation seeking, neuroticism–anxiety, aggression–hostility, sociability, and activityPages displaying wikidata descriptions as a fallback
• Big Five personality traits – Personality model consisting of five broad dimensions
• Cultural schema theory – Cognitive theory at the cultural level
• HEXACO model of personality structure – Six-dimensional model of human personality
• Minnesota Multiphasic Personality Inventory – Standardized psychometric measure of psychopathology and personality
• NEO-PI – Big Five personality trait inventoryPages displaying short descriptions of redirect targets
• Personality psychology – Branch of psychology focused on personality
• Social investment theory
• Szondi test – 1935 discredited psychological test
• Trait activation theory

References

1. Kassin S (2003). Psychology. U.S.: Prentice-Hall, Inc.
2. Northouse PG (2010). Leadership: theory and practice /. Sage Publications. ISBN 978-1-4129-7488-2.
3. Abel S. "What Is a Trait Two Basic Formulations". Personality Psychology. Retrieved 6 February 2018.
4. Long LM (1952). "Alfred Adler and Gordon W. Allport: A Comparison on Certain Topics in Personality Theory". American Journal of Individual Psychology. 10 (1). Chicago, Ill. Retrieved 2018-03-23.
5. Allport GW (1961). Pattern and growth in personality (14 print. ed.). New York: Holt, Rinehart and Winston. ISBN 978-0030108105.
6. • Eysenck H (1967). The biological basis of personality. Springfield, Ill.: Thomas.
   • Eysenck H (1991). "Dimensions of personality: 16: 5 or 3? Criteria for a taxonomic paradigm". Personality and Individual Differences. 12 (8): 773–790. doi:10.1016/0191-8869(91)90144-z.
7. McCrae RR, Costa PC Jr (1987). "Validation of the five-factor model across instruments and observers". Journal of Personality and Social Psychology. 52 (1): 81–90. doi:10.1037/0022-3514.52.1.81. PMID 3820081. S2CID 7893185.
8. Costa PT, McCrae RR (1992). "Four ways five factors are basic". Personality and Individual Differences. 13 (6): 653–665. doi:10.1016/0191-8869(92)90236-i. S2CID 86867568.
9. Marsella AJ, Dubanoski J, Hamada WC, Morse H (2000). "The measurement of personality across cultures: Historical conceptual, and methodological issues and considerations". American Behavioral Scientist. 44 (1): 41–62. doi:10.1177/00027640021956080. S2CID 144260384.
10. Mischel W, Shoda Y (1998-02-01). "Reconciling processing dynamics and personality dispositions". Annual Review of Psychology. 49 (1): 229–258. doi:10.1146/annurev.psych.49.1.229. ISSN 0066-4308. PMID 9496625.
11. Eysenck H (1990). "Biological dimensions of personality". In Pervin LA (ed.). Handbook of personality: Theory and research. New York: Guilford. pp. 244–76.
12. • Block J (1995). "A contrarian view of the five-factor approach to personality description". Psychological Bulletin. 117 (2): 187–215. doi:10.1037/0033-2909.117.2.187. PMID 7724687.
    • Draycott SG, Kline P (1995). "The Big Three or the Big Five—the EPQ-R vs the NEO-PI: a research note, replication and elaboration". Personality and Individual Differences. 18 (6): 801–804. doi:10.1016/0191-8869(95)00010-4.
13. Eysenck HJ (1992). "A reply to Costa and McCrae. P or A and C: The role of theory". Personality and Individual Differences. 13 (8): 867–868. doi:10.1016/0191-8869(92)90003-8.
14. Matthews G, Deary IJ, Whiteman MC (2003). Personality traits (2nd ed.). Cambridge: Cambridge University Press.
15. Eysenck H, Eysenck SB (1991). The Eysenck Personality Questionnaire-Revised. Sevenoaks: Hodder & Stoughton.
16. • Costa PT, McCrae RR (1990). "Personality disorders and the five factor model of personality". Journal of Personality Disorders. 4 (4): 362–371. doi:10.1521/pedi.1990.4.4.362.
    • Lynam DR, Caspi A, Moffitt TE, Raine A, Loeber R, Stouthamer-Loeber M (2005). "Adolescent psychopathy and the Big Five: Results from two samples". Journal of Abnormal Child Psychology. 33 (4): 431–443. doi:10.1007/s10648-005-5724-0. PMID 16118990. S2CID 24240140.
17. Eysenck HJ, Eysenck MW (1985). Personality and individual differences: A natural science approach. New York: Plenum.
18. Eysenck HJ (1967). The biological basis of personality. Springfield, Ill.: Thomas.
19. Eysenck HJ (1994). "Creativity and personality: Word association, origence, and Psychoticism". Creativity Research Journal. 7 (2): 209–216. doi:10.1080/10400419409534525.
20. Jeronimus BF, Riese H, Sanderman R, Ormel J (2014). "Mutual Reinforcement Between Neuroticism and Life Experiences: A Five-Wave, 16-Year Study to Test Reciprocal Causation". Journal of Personality and Social Psychology. 107 (4): 751–64. doi:10.1037/a0037009. PMID 25111305.
21. Eysenck HJ (1992). "The definition and measurement of psychoticism". Personality and Individual Differences. 13 (7): 757–785. doi:10.1016/0191-8869(92)90050-y.
22. Eysenck HJ (1997). "Personality and experimental psychology: The unification of psychology and the possibility of a paradigm". Journal of Personality and Social Psychology. 73 (6): 1224–1237. doi:10.1037/0022-3514.73.6.1224.
23. Stanek, Kevin; Ones, Deniz (2023-11-20). Of Anchors & Sails: Personality-Ability Trait Constellations. University of Minnesota. doi:10.24926/9781946135988. ISBN 978-1-946135-98-8. S2CID 265335858.
24. Stanek, Kevin C.; Ones, Deniz S. (2018), "Taxonomies and Compendia of Cognitive Ability and Personality Constructs and Measures Relevant to Industrial, Work and Organizational Psychology", The SAGE Handbook of Industrial, Work and Organizational Psychology: Personnel Psychology and Employee Performance, 1 Oliver's Yard, 55 City Road London EC1Y 1SP: SAGE Publications Ltd, pp. 366–407, doi:10.4135/9781473914940.n14, ISBN 978-1-4462-0721-5, retrieved 2024-02-24{{citation}}: CS1 maint: location (link)
25. DeYoung CG, Peterson JB, Higgins DM (Aug 2005). "Sources of openness/intellect: cognitive and neuropsychological correlates of the fifth factor of personality". Journal of Personality. 73 (4): 825–58. doi:10.1111/j.1467-6494.2005.00330.x. PMID 15958136.
26. • MacLaren VV, Best LA (Aug 2009). "Female students' disordered eating and the big five personality facets". Eating Behaviors. 10 (3): 192–5. doi:10.1016/j.eatbeh.2009.04.001. PMID 19665103.
    • Heaven PC, Mulligan K, Merrilees R, Woods T, Fairooz Y (Sep 2001). "Neuroticism and conscientiousness as predictors of emotional, external, and restrained eating behaviors". International Journal of Eating Disorders. 30 (2): 161–6. doi:10.1002/eat.1068. PMID 11449449.
    • Casper RC, Hedeker D, McClough JF (Sep 1992). "Personality dimensions in eating disorders and their relevance for subtyping". Journal of the American Academy of Child and Adolescent Psychiatry. 31 (5): 830–40. doi:10.1097/00004583-199209000-00008. PMID 1400113.
27. • Luo X, Kranzler HR, Zuo L, Wang S, Gelernter J (2007). "Personality Traits of Agreeableness and Extroversion are Associated with ADH4 Variation". Biological Psychiatry. 61 (5): 599–608. doi:10.1016/j.biopsych.2006.05.017. PMC 1853245. PMID 17069770.
    • Wright CI, et al. (Dec 2006). "Neuroanatomical correlates of extroversion and neuroticism". Cerebral Cortex. 16 (12): 1809–19. doi:10.1093/cercor/bhj118. PMID 16421327.
    • Mendez MF, Chen AK, Shapira JS, Lu PH, Miller BL (2006). "Acquired extroversion associated with bitemporal variant of frontotemporal dementia". Journal of Neuropsychiatry and Clinical Neurosciences. 18 (1): 100–7. doi:10.1176/appi.neuropsych.18.1.100. PMID 16525077.
28. • Rankin K, et al. (2004). "Right and left medial orbitofrontal volumes show an opposite relationship to agreeableness in FTD". Dementia and Geriatric Cognitive Disorders. 17 (4): 328–32. doi:10.1159/000077165. PMC 2362501. PMID 15178947.
    • Graziano WG, Tobin RM, et al. (Jun 1993). "Genetic and environmental effects on openness to experience, agreeableness, and conscientiousness: an adoption/twin study". Journal of Personality. 61 (2): 159–79. doi:10.1111/j.1467-6494.1993.tb01030.x. PMID 8345444.
    • Graziano W, Tobin R (October 2002). "Agreeableness: dimension of personality or social desirability artifact?". Journal of Personality. 70 (5): 695–727. doi:10.1111/1467-6494.05021. PMID 12322857.
29. Eysenck SB, Eysenck HJ (1969). "Scores on Three Personality Variables as a Function of Age, Sex and Social Class". British Journal of Social and Clinical Psychology. 8 (1). Wiley: 69–76. doi:10.1111/j.2044-8260.1969.tb00588.x. ISSN 0007-1293. PMID 5781476.
30. • Miller JL, et al. (Jan 2006). "Neuroticism and introversion: a risky combination for disordered eating among a non-clinical sample of undergraduate women". Eating Behaviors. 7 (1): 69–78. doi:10.1016/j.eatbeh.2005.07.003. PMID 16360625.
    • Takano A, et al. (Sep 2007). "Relationship between neuroticism personality trait and serotonin transporter binding". Biological Psychiatry. 62 (6): 588–92. doi:10.1016/j.biopsych.2006.11.007. PMID 17336939. S2CID 41664835.
    • Deckersbach T, et al. (2006). "Regional cerebral brain metabolism correlates of neuroticism and extraversion". Depression and Anxiety. 23 (3): 133–8. doi:10.1002/da.20152. PMID 16470804. S2CID 12798682.
31. Rosenberg M (1968) [1965]. Society and the Adolescent Self-Image. Princeton, N.J.: Princeton University Press. p. 18. ISBN 0691028052.
32. • Blascovich J, Tomaka J (1991). "Measures of self-esteem". In Robinson JP, Shaver PR, Wrightsman LS (eds.). Measures of personality and social psychological attitudes. Vol. I. San Diego, Calif.: Academic Press.
    • Button EJ (Jan 1997). "Self-esteem, eating problems and psychological wellbeing in a cohort of school age 15–16: question and interview". Int J Eat Disord. 21 (1): 39–41. doi:10.1002/(sici)1098-108x(199701)21:1<39::aid-eat5>3.0.co;2-4. PMID 8986516.
    • Strober M (1983). "Personality factors in anorexia nervosa". Pediatrician. 12 (2–3): 134–8. PMID 6400211.
    • Eiber R, et al. (2003). "Self-esteem: a comparison study between eating disorders and social phobia". Encephale. 29 (1): 35–41. PMID 12640325.
33. Bulik CM, et al. (1997). "Eating disorders and antecedent anxiety disorders: a controlled study". Acta Psychiatrica Scandinavica. 96 (2): 101–107. doi:10.1111/j.1600-0447.1997.tb09913.x. PMID 9272193. S2CID 21378266.
34. • Favaro A, Tenconi E, Santonastaso P (Apr 2008). "The relationship between obstetric complications and temperament in eating disorders: a mediation hypothesis". Psychosomatic Medicine. 70 (3): 372–7. doi:10.1097/PSY.0b013e318164604e. PMID 18256341. S2CID 347034.
    • Iidaka T, et al. (2006). "Volume of left amygdala subregion predicted temperamental trait of harm avoidance in female young subjects. A voxel-based morphometry study". Brain Research. 1125 (1): 85–93. doi:10.1016/j.brainres.2006.09.015. PMID 17113049. S2CID 16850998.
    • Peterson CB (Jan–Feb 2010). "Personality dimensions in bulimia nervosa, binge eating disorder, and obesity". Comprehensive Psychiatry. 51 (1): 31–6. doi:10.1016/j.comppsych.2009.03.003. PMC 2838502. PMID 19932823.
    • Gardini S, Cloninger CR, Venneri A (Jun 2009). "Individual differences in personality traits reflect structural variance in specific brain regions". Brain Research Bulletin. 79 (5): 265–70. doi:10.1016/j.brainresbull.2009.03.005. PMID 19480986. S2CID 25490518.
35. • Aron E, Aron A (1997). "Sensory-Processing Sensitivity and its Relation to Introversion and Emotionality" (PDF). Journal of Personality and Social Psychology. 73 (2): 345–368. doi:10.1037/0022-3514.73.2.345. PMID 9248053.
    • Aron E, Aron A, Jagiellowicz J (2012). "Sensory processing sensitivity: A review in the light of the evolution of biological responsivity" (PDF). Personality and Social Psychology Review. 16 (3): 262–282. doi:10.1177/1088868311434213. PMID 22291044. S2CID 2542035. Archived (PDF) from the original on May 13, 2015.
36. Benson E (November 2003). "The many faces of perfectionism". Monitor on Psychology. 34 (10).
37. • Halmi KA, et al. (Nov 2000). "Perfectionism in anorexia nervosa: variation by clinical subtype, obsessionality, and pathological eating behavior". American Journal of Psychiatry. 157 (11): 1799–805. doi:10.1176/appi.ajp.157.11.1799. PMID 11058477.
    • Ruggiero GM, et al. (Sep 2003). "Stress situation reveals an association between perfectionism and drive for thinness". International Journal of Eating Disorders. 34 (2): 220–6. doi:10.1002/eat.10191. PMID 12898558.
    • Hewitt PL, et al. (2008). "The impact of perfectionistic self-presentation on the cognitive, affective, and physiological experience of a clinical interview". Psychiatry. 71 (2): 93–122. doi:10.1521/psyc.2008.71.2.93. PMID 18573033. S2CID 1364808.
38. Muller RJ (2000). "When a patient has no story to tell: Alexithymia". Psychiatric Times. 17 (7): 1–6.
39. • Frewen PA, Pain C, Dozois DJ, Lanius RA (Jul 2006). "Alexithymia in PTSD: psychometric and FMRI studies". Annals of the New York Academy of Sciences. 1071 (1): 397–400. Bibcode:2006NYASA1071..397F. doi:10.1196/annals.1364.029. PMID 16891585. S2CID 15031115.
    • Guilbaud O, Corcos M, Chambry J, Paterniti S, Loas G, Jeammet P (2000). "[Alexithymia and depression in eating disorders]". Encephale. 26 (5): 1–6. PMID 11192799.
    • Smith GJ, et al. (Aug 1997). "Alexithymia in patients with eating disorders: an investigation using a new projective technique". Perceptual and Motor Skills. 85 (1): 247–56. doi:10.2466/pms.1997.85.1.247. PMID 9293583. S2CID 29307907.
40. • Peskine, A.; Picq, C.; Pradat-Diehl, P. (Dec 2004). "Cerebral anoxia and disability". Brain Injury. 18 (12): 1243–54. doi:10.1080/02699050410001719899. PMID 15666568. S2CID 22416252.<
    • Ho AK, Robbins AO, Barker RA (Mar 2006). "Huntington's disease patients have selective problems with insight". Movement Disorders. 21 (3): 385–9. CiteSeerX 10.1.1.511.6208. doi:10.1002/mds.20739. PMID 16211608. S2CID 12076025.
    • Tchanturia K, et al. (Sep 2001). "Perceptual illusions in eating disorders: rigid and fluctuating styles". Journal of Behavior Therapy and Experimental Psychiatry. 32 (3): 107–15. doi:10.1016/s0005-7916(01)00025-8. PMID 11934124.
    • Cserjési R (Jun 2009). "Affect, cognition, awareness and behavior in eating disorders. Comparison between obesity and anorexia nervosa". Orvosi Hetilap. 150 (24): 1135–43. doi:10.1556/OH.2009.28590. PMID 19482720.
41. Eysenck SB, Eysenck HJ (Feb 1977). "The place of impulsiveness in a dimensional system of personality description". British Journal of Social and Clinical Psychology. 16 (1): 57–68. doi:10.1111/j.2044-8260.1977.tb01003.x. PMID 843784.
42. • Bechara A, Damasio AR, Damasio H, Anderson SW (Apr–Jun 1994). "Insensitivity to future consequences following damage to human prefrontal cortex". Cognition. 50 (1–3): 7–15. doi:10.1016/0010-0277(94)90018-3. PMID 8039375. S2CID 204981454.
    • Eysenck SB, Eysenck HJ (Feb 1977). "The place of impulsiveness in a dimensional system of personality description". British Journal of Social and Clinical Psychology. 16 (1): 57–68. doi:10.1111/j.2044-8260.1977.tb01003.x. PMID 843784.
    • Welch SL, Fairburn CG (Oct 1996). "Impulsivity or comorbidity in bulimia nervosa. A controlled study of deliberate self-harm and alcohol and drug misuse in a community sample". British Journal of Psychiatry. 169 (4): 451–8. doi:10.1192/bjp.169.4.451. PMID 8894196. S2CID 32042767.
    • Corstorphine E, Waller G, Lawson R, Ganis C (Jan 2007). "Trauma and multi-impulsivity in the eating disorders". Eating Behaviors. 8 (1): 23–30. doi:10.1016/j.eatbeh.2004.08.009. PMID 17174848.
    • Patton JH, Stanford MS, Barratt ES (November 1995). "Factor structure of the Barratt impulsiveness scale". Journal of Clinical Psychology. 51 (6): 768–74. doi:10.1002/1097-4679(199511)51:6<768::aid-jclp2270510607>3.0.co;2-1. PMID 8778124.
    • Chamberlain SR, Sahakian BJ (May 2007). "The neuropsychiatry of impulsivity". Current Opinion in Psychiatry. 20 (3): 255–61. doi:10.1097/YCO.0b013e3280ba4989. PMID 17415079. S2CID 22198972.
43. • Smith CF (Mar 1998). "Association of dietary restraint and disinhibition with eating behavior, body mass, and hunger". Eating and Weight Disorders. 3 (1): 7–15. doi:10.1007/bf03354907. PMID 11234257. S2CID 40567168.
    • Bryant EJ, King NA, Blundell JE (Sep 2008). "Disinhibition: its effects on appetite and weight regulation". Obesity Reviews. 9 (5): 409–19. doi:10.1111/j.1467-789X.2007.00426.x. hdl:10454/5739. PMID 18179615. S2CID 2710954.
    • Grekin ER, Sher KJ, Wood PK (December 2006). "Personality and substance dependence symptoms: modeling substance-specific traits". Psychology of Addictive Behaviors. 20 (4): 415–24. doi:10.1037/0893-164X.20.4.415. PMID 17176176.
    • Young SE, Stallings MC, Corley RP, Krauter KS, Hewitt JK (October 2000). "Genetic and environmental influences on behavioral disinhibition" (PDF). American Journal of Medical Genetics. 96 (5): 684–95. CiteSeerX 10.1.1.474.4776. doi:10.1002/1096-8628(20001009)96:5<684::aid-ajmg16>3.0.co;2-g. PMID 11054778.
    • Young SE, et al. (Feb 2009). "Behavioral disinhibition: liability for externalizing spectrum disorders and its genetic and environmental relation to response inhibition across adolescence". Journal of Abnormal Psychology. 118 (1): 117–30. doi:10.1037/a0014657. PMC 2775710. PMID 19222319.
    • Emond V, Joyal C, Poissant H (Apr 2009). "Structural and functional neuroanatomy of attention-deficit hyperactivity disorder (ADHD)". Encephale. 35 (2): 107–14. doi:10.1016/j.encep.2008.01.005. PMID 19393378.
    • Spiegel DR, Qureshi N (2010). "The successful treatment of disinhibition due to a possible case of non-human immunodeficiency virus neurosyphilis: a proposed pathophysiological explanation of the symptoms and treatment". General Hospital Psychiatry. 32 (2): 221–224. doi:10.1016/j.genhosppsych.2009.01.002. PMID 20303000.
    • Aarsland D, Litvan I, Larsen JP (2001). "Neuropsychiatric symptoms of patients with progressive supranuclear palsy and Parkinson's disease". Journal of Neuropsychiatry and Clinical Neurosciences. 13 (1): 42–9. doi:10.1176/appi.neuropsych.13.1.42. PMID 11207328.
44. • Eysenck HJ, Eysenck SB (1977). Psychoticism as a Dimension of Personality. London: Hodder and Stoughton. ISBN 978-0-340-20919-6.
    • Lester D (1989). "A Neurotransmitter Basis for Eysnenck's Theory of Personality". Psychological Reports. 64 (1): 189–190. doi:10.2466/pr0.1989.64.1.189. ISSN 0033-2941. PMID 2564688. S2CID 28744688.
45. • Zubieta JK (1995). "Obsessionality in eating-disorder patients: relationship to clinical presentation and two-year outcome". Journal of Psychiatric Research. 29 (4): 333–42. doi:10.1016/0022-3956(95)00020-6. PMID 8847659.
    • Salkovskis PM, Forrester E, Richards C (1998). "Cognitive-behavioural approach to understanding obsessional thinking". British Journal of Psychiatry Supplement. 173 (35): 53–63. doi:10.1192/S0007125000297900. PMID 9829027. S2CID 32544419.
    • Corcoran KM, Woody SR (Jan 2008). "Appraisals of obsessional thoughts in normal samples". Behaviour Research and Therapy. 46 (1): 71–83. doi:10.1016/j.brat.2007.10.007. PMID 18093572.