This book provides a detailed explanation of the Big Five personality model. Although the explanation of the model itself was interesting, the most valuable parts of the book were the first and last chapters.

The first chapter establishes how personality models like the Big Five are generated. Unlike models with less construct validity, these models do not start with a schema and then put people into it. Instead, these models start by asking behavioral questions and then looking for clusters of correlated behaviors. These clusters become the characteristics of the personality model. Although these models are determined statistically, it is hypothesized (though not yet verified) that the reason such clusters of related behaviors exist is because they correspond to underlying tendencies in the brain. E.g., the cluster of behaviors that are labeled "Extroversion" in the Big Five model all seem to be related by an individual's reactivity to rewards. Another interesting thing to note about this method of building a personality model is that every personality factor is a continuum. Models which try to push people into discrete buckets generally fail to have statistical validity.

The second chapter is a look into the question of why personality variation exists. Nettle makes the argument that variation exists because for every personality trait, there are some situations where being high on a trait is advantageous and some situations where being low on that trait is advantageous. Even neuroticism (sometimes called low emotional stability), which seems unrelentingly negative in the modern world, can be beneficial for individuals who live in a dangerous situation. Environments tend to change more quickly than evolution can normalize to a smaller range of variation.

The first of the ending chapters discusses the factors that determine personality. Heritability is a large factor, but explains, in general, only about half of the variation in personality. General environmental factors fail to explain the rest, but specific environmental cues can influence personality. E.g., certain types of chronic threat may increase neuroticism. Cues during gestation can affect fetal development. The final factor, and perhaps the most interesting one, is that one's own characteristics can influence how one responds to environmental cues in a way that can, over time, influence personality. E.g., someone who is conventionally attractive may get more positive enforcement when they act in extroverted ways and so their extroversion may end up larger than someone who had a similar inherited background but less positive reinforcement. (By the way, another interesting thing noted in this book is that personality factors can and do change somewhat over time. They're stable but not fixed.)

The last chapter was a look at how to live with our personalities. The first point Nettle makes is that no personality configuration is "good" or "bad". Each is what it is. That said, personalities do influence our characteristic behaviors and how we structure our life narratives. Someone with low conscientiousness is less likely to inhibit harmful behaviors such as a drug or alcohol addition. Someone with high neuroticism is likely to construct their life narrative more negatively than someone lower on that scale who experienced the same events. But personality is not destiny. Personality characteristics are interesting because they predict behaviors at a level that is well above chance, but there is still plenty of variation. As Nettle points out in a thought experiment, if someone were like you on all of the personality traits, you're likely to understand the choices they make, but there are still lots of different choices you can make. E.g., the alcoholic who knows they can't stop at just one drink could choose to drink or could choose to avoid alcohol completely. The person whose agreeableness is high enough that they often neglect themselves could choose to run themselves ragged helping others or find some way -- such as pre-scheduled time -- to take care of themselves.

All in all, I found this book to present an interesting and balanced view of what personality is and how it influences our lives. ( )

Personality: What Makes You the Way You Are by Daniel Nettle. Library section 8B: Life Skills: Personal Growth. This fascinating book explains the “big five” personality types and how they manifest in the way we act and think. High scorers for “Extraversion” are outgoing and enthusiastic; low scorers are aloof and quiet. High scorers of “Neuroticism” are prone to stress and worry; low scorers are emotionally stable. High scorers of “Conscientiousness” are organized and self-directed; low scorers are spontaneous and careless. High scorers of “Agreeableness” are trusting and empathetic; low scorers are uncooperative and hostile. High scorers of “Openness” are creative, imaginative or eccentric; low scorers are practical and conventional.
Our personalities are all combinations of these types, but one often predominates. You can infer that if a parent is not conscientious, they will be less able to provide steady family involvement, a sensible routine, or quality parenting. Therefore if you prefer a steady and trustworthy spouse, you should select a conscientious self-starter who is self-directed and organized. We inherit our personality type. It creates about 50% of our personality. What is the rest? The rest might derive from early life experiences, illness, parenting, family structure, school life, friends – what we often call “nurture.” However, psychologists do not know much about these variables. How nurture and environment affects us is actually a very undeveloped area of psychology that is still largely unknown. Studies of identical twins reveal that those who were separated at birth and grew up apart have startlingly similar personalities, so nurture may have little to do with adult personality.
Which personality type of the five above do you think YOU are? I think I am high in “Openness” because I am an artist, creative, love to write and read, and express myself best through art, writing and music. I am open and accepting toward many kinds of people because art school taught me to accept and get along with students who were highly individual, unique and even eccentric. I also am “Conscientious” because I am organized and self-directed, have a smidge of “Agreeableness” (arguing upsets me), and “Neuroticism” (I have my worries like anyone else, but they do not drive my personality).
Determining your personality type gives you insight into who you are, why you make the choices you do, and how you can adjust your personality in beneficial ways if that is your desire. ( )

What determines your personality? Which is the best personality to have? Are you stuck with your personality, or can you change it?

Daniel Nettle looks at the science of human personality, exploring the rich variety of our natures, how they might have evolved, and how all personalities can now be mapped remarkably accurately against just five simple measures. This book will make you look afresh at yourself and at those around you, and give you new insights into your own personality. It won't tell you how you should live, but it might just help you live life to your strengths.

Nettle posits in the introduction to Personality that life is nothing but a series of leitmotifs which can be predicted by an individual's personality. Unlike other personality theories like the Myers-Briggs, Nettle touts the five-factor model developed by Paul Costa and Robert McCrae which has been determined by statistical observations--when different traits were analyzed for correlations, they clustered into five groups heretofore labeled as extraversion, neuroticism, conscientiousness, agreeableness, and openness. Because humans are social animals and we need to act in certain ways to ensure cooperation and survival, the main thesis of the book is that personality is an outgrowth of evolutionary fitness. (more)

Very difficult read, very dull writing style. ( )