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Author: Shahroze Suzuki, TMH PsychologistShahroze Suzuki

Table of Contents

What is Personality?

According to the American Psychological Association, Personality is defined as; the enduring characteristics and behavior that comprise a person’s unique adjustment to life, including major traits, interests, drives, values, self-concept, abilities, and emotional patterns. Various theories explain the structure and development of personality in different ways, but all agree that personality helps determine behavior.

In other words, personality is a stable pattern of thinking and feeling that can be used to explain behaviour and the different patterns of behaviour between individuals.

TMH resource page Personality and personality disorder

Theories of Personality

There are a vast array of theories of personality that can be categorised according to psychological tradition into dispositional, humanistic, biological, behavioural and psychodynamic models. As well as accounting for behaviour, some theories of personality such as Freud’s psychosexual stages and Erikson’s psychosocial theory, have also attempted to explain how personality ties in with our psychological development. However, I am going to focus on one particular model, a dispositional model, that has, over recent years, become increasingly mainstream and accepted among personality researchers.

Five Factor Model

The ‘Big 5,’ ‘Five Factor Model’ or ‘O.C.E.A.N model’ conceptualises personality in 5 trait domains, which are Openness, Conscientiousness, Extraversion, Agreeableness and Neuroticism. These 5 factors were derived from lexical analysis. A process called factor analysis then looked at similarities and correlations between these adjectives used to describe individuals in daily conversations and finally, statistically narrowed it down to these 5 traits.

  1. Openness can be described as a tendency to welcome new experiences and unconventional beliefs. Openness has shown correlations with creativity and curiosity. On the other hand, a high score on openness can generally mean unpredictability, an increased likelihood to engage in risky activities and seeking out intense euphoric experiences. Whereas, low openness indicates closed mindedness, a more traditional outlook and a bias towards familiarity. 
  2. Conscientiousness is a trait which in other words is known as self-discipline. It is the capacity to organise, regulate and desire to have control over certain outcomes. A highly conscientious person may be regarded as someone who is punctual, orderly, well-planned and desires mastery. A low conscientiousness could mean a desire for spontaneity and impulsivity. In extreme cases, conscientiousness could also mean an obsessive desire for perfection and control which we see in certain personality disorders such as obsessive compulsive personality disorders.
  3. Extraversion or rather extraverted individuals are known to enjoy social interactions. They seem more energised and upbeat and often take charge of social situations. The opposite of extraversion; introversion correlates with preference and comfortableness to spend time alone. Introverts are more independent in the social world as compared to extraverts.
  4. The trait for Agreeableness reflects cooperation and the tendency to value social harmony. Individuals who do show agreeableness can come off as being more approachable, considerate, kind, trustworthy and helpful. However, an extremely high agreeableness can result in submissiveness or even dependency. Low agreeableness can be regarded as assertiveness, competitive, argumentative or even unfriendly. In extreme cases, it can also be expressed as paranoia and rebelliousness. 
  5. The trait for Neuroticism addresses the tendency to be sensitive towards negative emotions. An individual with neuroticism will tend to experience more negative emotions such as anger, anxiety, sadness and hopelessness as compared to those with less neuroticism. Neuroticism is sometimes also conceptualised as emotional instability as those with high neuroticism tend to have a lower threshold to stress and aversive stimuli. Individuals with lower neuroticism can be regarded as being more calm, emotionally stable and less reactive. According to research, high neuroticism is said to have been linked to poorer mental health.

Are behavioural traits all there is to personality?

When we think of personality, we often think in terms of traits, and indeed, most objective personality assessment quantifies personality in those terms. However, Dan McAdams offers a model of personality that is more than just our traits. Through his research, McAdams portrays a more holistic view of personality. According to him, there are 3 layers of personality.

  1. Social Actor: The first layer of personality aims to describe the type of individual we are in our most recognizable aspects – traits (no surprise!). Traits allow for prediction of behavioural tendencies and also explain some of the individual differences in emotion and behavioural characteristics between people. This first layer is said to have been formed in infancy and focuses on maximising the utilisation of one’s signature traits on the social stage. This layer also explains our behaviour across context and time, and our capacity to perform in a socially desirable manner (to ‘get along’ as McAdam’s puts it) as well as our capacity to excel (to ‘get ahead’).
  2. Motivated Agent: The second layer of personality adds on top of the first layer as social actor. The second layer forms during our late childhood years. The core focus here is to pursue your most cherished goals and values to the fullest extent you can, as well as understanding your own identity. This layer consists of varieties of adaptations which can help the individual formulate and specify their goals, act in alignment with their values and express themselves in accordance to the demands of time, place and the social role they find themselves in.
  3. Autobiographical Author: Though people can be understood in terms of traits, motivations and values, according to McAdams, to truly be able to know a person, an inspection of their self-narrative is essential. McAdams pointed out that people vary with regards to what narrative they give to their lives and experiences. According to McAdams, this layer of personality develops during adulthood, during which coherent meaning is derived from past experiences combined with present circumstances and future desires. The focus here is the integrative life story from which individuals can derive personal meaning about their life and existence.

How does personality relate to the brain?

Some neuroscientists have put forward neurobiological models of personality. The Affective Neuroscience Theory by Jaak Panksepp for example, highlighted seven primary emotion systems in the mammalian brain, called SEEKING, LUST, CARE, PLAY (positive emotions) and FEAR, ANGER, SADNESS (negative emotions). These systems, according to Panksepp, are a result of evolutionary processes and act to help mammals survive. Panksepp argues that the differences in the make up of these primary emotions for each person could explain individual differences. These primary emotions systems can also be thought of as underlying and related to the 5 personality traits in the five factor model. For example, SEEKING and PLAY may relate to Openness and Extraversion, whereas FEAR, ANGER and SADNESS seem to relate strongly to Neuroticism.

What is Temperament?

When discussing personality, questions of temperament often arise. According to Jerome Kagan, one of the pioneers of developmental psychology and known as the father of temperamental psychology, temperament is the neurochemical biases that we begin our life with. These biases, according to Kagan, are prenatal and are woven into personality traits as we develop. 

Kagan’s research on temperament focused on two types of temperament within children; inhibited and uninhibited. According to Kagan, an inhibited child would have a timid, fearful and reserved profile whereas an uninhibited child comparatively would have a more social, bolder profile. Kagan’s 1991 study highlights this phenomenon in which 94 infants were exposed to unfamiliar stimuli. Infants that showed high reactivity (frequent crying and high motor activity) were later seen to have higher levels of fear at the age of 9 compared to those who showed a lower level of reactivity to the novel stimuli. This suggests that temperament has the ability to influence future behaviour based on how an individual reacts to their environment.

Other researchers such as Thomas and Chess proposed 3 different temperaments with regards to infants; Easy, slow-to-warm and difficult. According to Thomas and Chess, infants with an easy temperament are generally more happy, energetic and adjust to novel situations rather well. Children with a slow-to-warm temperament are described to be more laid-back as compared to easy children. They also take time adjusting to new situations as compared to easy. Difficult children are described as having irregular routines and habits. They also do not react well to novel situations as compared to children having the other two types of temperament.

Thomas and Chess further identified 9 dimensions to help indicate temperaments in individuals. According to Thomas and Chess, by identifying temperament in children, caregivers would be able to foster an appropriate nurturing environment. This was important for the child as according to them, providing an environment that matched well with the child’s temperament would allow the child to do better later in life.

The 9 dimensions proposed by Thomas and Chess are:

  1. Activity (Energetic vs. Inactivity) – Level of physical activity
  2. Regularity (Routine vs. Varied) – Consistency for routine activities and also how flexible individuals are within their routines. 
  3. Initial reaction (Open vs. Hesitant) – Acceptance or rejection of new, unfamiliar experiences.
  4. Adaptability (Accommodating vs. Resistant)– Ability to respond to changes in the environment and transition between activities.
  5. Intensity (Excitement vs Lethargy)– The intensity of their subjective experiences to external stimuli.
  6. Mood (Positive vs. Negative)– Which mood does the individual experience mostly; negative or positive mood.
  7. Distractibility (Attentive vs. Distracted) – How easily can one be distracted from what they were engaged in.
  8. Persistence/attention span (Invested vs. Disinterested)- The amount of time one can stay focused at the task at hand and also the level of determination they exhibit to see things though.
  9. Sensory threshold (Unaffected vs. Irritated – How the child responds to different sensory stimuli. High threshold would mean that the child is unaffected and is comfortable with increased stimuli. Those with a low threshold may be irritated instead. 

In summary, temperament can be thought of as individual differences in neurobiological systems which help to facilitate approach or avoidance behaviors. Sometimes, a similar scenario could elicit different behaviors in individuals due to their innate differences in reactivity and regulation. How we react and regulate allows us to develop an understanding of our social environment, according to which we can then choose to engage how we see fit.

Is Personality Really Stable Over Time?

The short answer to the question: is personality really stable over time? is that it is relatively stable. Many might consider personality to be fixed. However, research suggests that our personality traits do change across a lifetime. 

The stability of traits is often measured in test-retest correlations. According to studies such as Fraley & Roberts, 2005 and Roberts & DelVecchio, 2000, we can come up with two conclusions:

  1. Personality traits are moderately stable over time with correlations (rank order stability) ranging between 0.4 to 0.6 over 10-year time periods. However, some research like Damian et al. (2019) found the rank-order stabilities of traits to lie around 0.2 across extended time periods spanning more than 3 decades.
  2. Secondly, there are specific time periods when personality traits are more stable than in the other periods. Looking at rank-order stability again, personality trait stability is said to peak at around 60 years of age and is more prone to changes during one’s youth and old age.

What is a Personality Disorder?

A personality disorder is an enduring disturbance in patterns of thinking, feeling and behaving characterized by impaired functioning in aspects of the self and/or interpersonal dysfunction.

We can see this for ourselves with regards to how the DSM and the ICD have defined personality disorders:

Personality Disorder according to DSM 5/5-TR

An Enduring pattern of inner experience and behavior that deviates markedly from the expectations of the individual’s culture. This pattern is manifested in two (or more) of the following areas:

  1. Cognition 
  2. Affectivity
  3. Interpersonal functioning
  4. Impulse control

Personality Disorder according to ICD 11

Personality disorder is characterised by problems in functioning of aspects of the self (e.g., identity, self-worth, accuracy of self-view, self-direction), and/or interpersonal dysfunction (e.g., ability to develop and maintain close and mutually satisfying relationships, ability to understand others’ perspectives and to manage conflict in relationships) that have persisted over an extended period of time (e.g., 2 years or more). The disturbance is manifest in patterns of cognition, emotional experience, emotional expression, and behaviour that are maladaptive (e.g., inflexible or poorly regulated) and is manifest across a range of personal and social situations (i.e., is not limited to specific relationships or social roles). The patterns of behaviour characterizing the disturbance are not developmentally appropriate and cannot be explained primarily by social or cultural factors, including socio-political conflict. The disturbance is associated with substantial distress or significant impairment in personal, family, social, educational, occupational or other important areas of functioning.

How researchers and doctors think about personality disorder has changed in the last decade. The two diagnostic systems of ICD 10 by WHO and the DSM- IV, 5 and the 5TR by American Psychiatric Association conceptualized personality disorders as a series of categories as listed below:

ICD 10

  • Paranoid personality disorder
  • Schizoid personality disorder
  • Dissocial personality disorder
  • Emotionally Unstable personality disorder
  • Histrionic personality disorder
  • Anankastic personality disorder
  • Anxious personality disorder
  • Dependent personality disorder
  • Other Specified personality disorder (Eccentric, Narcissistic, Haltose, Immature, Passive-aggressive, Psychoneurotic)


The DSM- IV, DSM-5 & DSM-5 TR categorise personality disorders into 3 clusters.

  • Cluster A (Eccentric or odd patterns of thinking and behaviour)
    • Paranoid personality disorder
    • Schizoid personality disorder
    • Schizotypal personality disorder
        • Cluster B (Dramatic or overly emotional patterns of thinking and behavior)
          • Antisocial personality disorder
          • Borderline personality disorder
          • Histrionic personality disorder
          • Narcissistic personality disorder
                • Cluster C (Anxious or fearful patterns of thinking and behavior)
                  • Avoidant personality disorder
                  • Dependent personality disorder
                  • Obsessive-compulsive personality disorder

                  However, in the last decade, there has been a shift as to how psychologists and psychiatrists look at personality disorders. Although the basic definition of pervasive patterns of thinking, feeling and behaving which can be seen as causing impaired intrapersonal and interpersonal functioning still stands, recent changes seen in the ICD-11 and the proposed alternative model of personality disorders in the DSM 5 & 5TR conceptualize personality disorders as dysfunctions in self and interpersonal relationships associated with a range of high scores on dimensional personality traits. These traits are similar to, and map onto, the 5 personality factors of the Five Factor Model above.


                  The Alternative Model of Personality Disorders, added to the DSM in the 2013 5th edition, includes 2 parts. The first part consists of Criterion A, which is to do with the ‘level of personality functioning’ (LPF), defined as impairments or deficits in the sense of self and interpersonal relatedness. The second part, Criterion B, involves a five-domain maladaptive trait model, somewhat analogous to the FFM above. Including both these criteria means that the AMPD profile illustrates not only if individuals are impacted with regards to personality disorder but also how they are impacted as well.

                  Criterion A

                  When comparing the AMPD with the more classic diagnostic criteria of section 2 of the DSM 5 and 5 TR, the first notable difference we see is that the personality functioning is now defined in these four categories, two ‘internal’ and two ‘external’ —identity, self-direction (both internal), then empathy, and intimacy (both external). According to the general criteria of AMPD, there needs to be a moderate level of impairment in at least one component of both internal and external functioning. This is different from section 2’s general criteria for impairment in cognition, affectivity, interpersonal functioning and impulse control. 

                  Criterion B

                  The AMPD also identifies five broad domains of maladaptive personality traits, which are measured on a continua. These five traits can be thought of as maladaptive variations of the five domains of the Big Five or the Five Factor Model.

                  The 5 trait specifiers, (and the related Big 5 traits) are:

                  1. Negative Affectivity (Neuroticism): The tendency to experience negative emotions, such as anxiety, depression, and emotional lability.
                  2. Detachment ( Low Extraversion): The tendency to withdraw from and avoid emotional connections with others.
                  3. Antagonism (Low Agreeableness): The tendency to be hostile, manipulative, and uncooperative with others.
                  4. Disinhibition (Low Conscientiousness): The tendency to act impulsively and irresponsibly without considering the consequences.
                  5. Psychoticism (Openness): The presence of unusual or bizarre thoughts and behaviors.

                  Moreover, the AMPD also mentions 6 DSM-IV personality disorder constructs, working within the AMPD framework. The intent being was to show how specific DSM-IV personality disorders could be understood as specific combinations of personality functioning and pathological traits, as opposed to categorical symptom lists. So, while the primary focus of the AMPD is on maladaptive personality traits and levels of personality functioning, it also allows for the recognition of specific personality disorder types. The 6 DSM- IV personality disorders mentioned in the AMPD are:

                  • Borderline Personality Disorder
                  • Avoidant Personality Disorder
                  • Narcissistic Personality Disorder
                  • Antisocial Personality Disorder
                  • Schizotypal Personality Disorder
                  • Obsessive Compulsive Personality Disorder

                  There is some evidence that the AMPD has been found to be more useful in clinical settings than the DSM-5 and DSM-5 TR section 2, especially for planning treatment and also predicting treatment outcomes.

                  ICD 11

                  When compared to the ICD-10, ICD-11 takes a new approach to define personality disorders, building on some of the earlier developments described above. Here are a few areas where the concept has evolved:

                  1. Impairments in aspects of self and the interpersonal

                  Similar to DSM-5’s AMPD, ICD-11 accounts for personality dysfunction as impairments in aspects of the self (e.g., identity, self-worth, accuracy of self-view, self-direction), and the interpersonal (e.g., ability to develop and maintain close and mutually satisfying relationships, ability to understand others’ perspectives and to manage conflict in relationships). 

                  2. Duration of symptoms

                  ICD-11 also adds a time-based criteria of 2 years or more for these dysfunctions. In contrast to AMPD, ICD-11 diagnostic criteria do not require personality disorders to have their onset in adolescence. Furthermore, ICD-11 also integrates patterns of cognition, emotional experiences and behaviour into its diagnostic criteria for personality disorders, much like the section 2 of DSM-5/TR. 

                  3. Dimensional trait rather than categories

                  Similar to DSM-5 AMPD, instead of categorizing personality disorders as in ICD 10, the new diagnostic criteria list dimensional trait analogous in part to the Big 5 traits as ‘domain specifiers’

                  1. High Neuroticism as Negative Affectivity
                  2. Low Extraversion as Detachment
                  3. Low Conscientiousness as Disinhibition
                  4. Low Agreeableness as Dissociality 
                  5. High Conscientiousness as Anankastia 
                  6. Borderline Pattern

                  The 6th domain specifier known as Borderline Pattern has some controversy surrounding it as it may not be a trait on its own but rather a mixture of negative affectivity, dissociality and detachment. It was a last minute addition to the ICD 11. There are arguments supporting the inclusion of Borderline Pattern as it can be used to distinguish the severity of negative affectivity such as that indicated by self harm and unstable relationships.

                  4. Assessing severity of the disorder

                  Furthermore, the ICD 11 utilises a spectrum to map out the severity of personality disorders consisting of a scale starting with personality difficulty, then continuing with mild personality disorder, moderate personality disorder and severe personality disorder. The inclusion of personality difficulty can be used to highlight individuals that have pronounced personality characteristics that may affect treatment or access to health services but do not rise to the level of severity to merit a diagnosis of Personality Disorder.

                  What Do We Know About the Prevalence of Personality Disorders?

                  According to a 2020 meta analysis research which included 21 countries across 6 different continents, the prevalence rate for any personality disorder in the general population was estimated to be 7.8%

                  Within personality disorders, as conceptualised using the older models of personality disorder, some types of personality disorder have been found to be more common than others as highlighted by the table below:

                  Personality DisorderRate in General populationRate in Clinical PopulationRates within a sample of 546 patients in specialist personality disorder services
                  Antisocial0.2-3%Above 70% for males from substance abuse clinics, forensic settings and those with alcohol usage disorder< 1%
                  NarcissisticUp to 5%6%3%
                  Obsessive Compulsive3-4%Up to 8%7%
                  Paranoid0.5-5%Up to 4%8%
                  Dependent< 1%0.5-0.6 %

                  These numbers suggest that rates of personality disorder in a clinical population can vary quite a lot based on the nature of the service. Also it seems people with some personality disorders (for example those said to have borderline personality disorder or avoidant personality disorder) are more likely to be seeking help from clinical services than other personality disorders, such as narcissistic personality disorder.

                  How is Assessing Personality Useful?

                  Attempts to assess and explain personality can be traced back to ancient times. Our methods may be more scientifically streamlined using reliable and validated instruments to measure aspects of personality now but our desire to understand personality remains the same. 

                  Personality assessment can provide useful insight regarding an individual’s behavioural tendencies, values and self-concept, which can be used to help understand patterns of behaviour within particular settings.

                  Some personality instruments can be used to understand how we approach relationships, regulate negative emotions, approach novel situations, how we cope with overwhelming experiences and how we make decisions.

                  Moreover, personality assessments can also help highlight interests and strengths as well as areas of psychological need. In a clinical setting, this is useful for mapping out therapeutic interventions and goals with a therapist, making sure they are aligned with the individual’s motivators and value systems. According to research, for example, tapping into strengths and utilising them in everyday life such as our work can influence job satisfaction. In other non-clinical setting, understanding our motivators and strengths can be used to map out hobbies, career paths and educational pursuits.

                  In summary, personality assessments allow us to know our habitual patterns of thinking, feeling and behaving, how to utilise our strengths more effectively, what aspects of ourselves we need to look out for, and most importantly work on, and how we habitually relate to the world around us.

                  Mentalization and Personality Disorders

                  In order to comprehend intentional mental states like feelings, desires, wishes, goals, and attitudes in ourselves and in others, mentalization is crucial. Mentalization to sum it up can be conceptualised as a cognitive process that allows individuals to interpret and make sense of emotions and motivations in themselves and others.

                  Mentalization is a term that has evolved from concepts like Daniel Dennett’s intentional stance which can be described as individuals attributing beliefs, desires, and intentions to others in order to make sense of their actions and Simon Baron Cohen’s Theory of Mind, which refers to the ability to understand that other people have their own thoughts, beliefs, desires, and intentions that may be different from one’s own. We can think of mentalization as a broader term that includes these other concepts. 

                  Mentalization can be thought of as a skill that humans quickly acquire, much like our capacity to acquire language. However, this can be more challenging for some individuals, for example, for those with ASD. Temple Grandin, for example, has described how mentalization skills can be explicitly learned and developed over time. Subtle problems with mentalization are also thought to relate to some common problems seen in certain personality disorders.

                  Therapeutic approaches such as Mentalization-Based Therapy, developed specifically for the treatment of personality disorders, focus on enabling clients to better understand themself and others. This therapeutic approach aims to enable clients to improve how well they can comprehend their thoughts and emotions, along with understanding and representing what others might be feeling, so that they may experience better communication and deeper understanding.

                  Neurodevelopmental Disorders and Personality Disorders

                  Recent researches have highlighted how neurodevelopmental conditions and personality disorders can substantially overlap.

                  ASD and Personality Disorders

                  Individuals with ASD exhibit increased sensitivity to sensory stimuli, preference for routine, and challenges in social interactions. These temperament characteristics can be also seen as personality traits in adulthood. For example, high sensitivity to sensory input may relate to elevated negative affectivity or emotional reactivity. Those on the autism spectrum may occasionally exhibit personality traits similar to certain previously defined personality disorders, for example avoidant personality disorder which can be seen as dispositional profound social anxiety and interpersonal difficulties, or obsessive-compulsive personality disorder, which is characterised by inflexible insistence on customs and protocols. In terms of the dimensional framework of AMPD and ICD-11 introduced above, individuals with ASD may for example be prone to scoring higher on personality measures of detachment.

                  ADHD and Personality Disorders

                  Hyperactivity, and difficulty with sustained attention could be described as the hallmark features of ADHD. Those with ADHD then may be seen to display impulsivity, also seen in personality disorders such as emotionally unstable personality disorder, where people struggle with control of emotionally-motivated behaviour, or antisocial personality disorder, where both impulsivity and a lack of regard for others are central issues. Those with ADHD may score higher on measures of disinhibition and detachment in the AMPD and ICD-11 framework.

                  What TMH Offers

                  At Tokyo Mental Health we provide mental health assessment services in English, both online and in-person. These assessments can include detailed assessment of personality, where indicated. Our personality assessment includes tapping into multiple distinct domains such as:

                  • Behavioral traits
                  • Personality functioning
                  • Motivation, interests & values
                  • Attachment style
                  • Emotional dysregulation
                  • Childhood experiences
                  • Executive functioning
                  • Temperament
                  • Coping strategies
                  • Skills
                  A diverse group of people congratulating

                  We also provide online and in-person counselling for treatment of personality disorders utilising evidence-based approaches such as individual Dialectical Behavior Therapy (DBT), Cognitive Behavioral Therapy (CBT) and Emotionally Focused Therapy (EFT).