PSYC 2P25 – Personality and Individual Differences Sep. 10, 2012
How can personality be measured?
What are the “basic” personality characteristics?
How (and how much) does personality change across the life span?
How do hormones and brain chemicals relate to personality?
How much does heredity influence personality?
What features of your childhood influence your personality in adulthood?
Why did personality differences evolve?
How does personality affect life outcomes (e.g. health, happiness, career, law, relationships, etc.)?
What is “intelligence”, and does it matter in real life?
Do your religions and political views depend on you personality?
How does personality relate to sexuality?
Two approaches to study of personality
o Idiographic approach: try to understand each individual’s complex, unique features
used in biographies, fiction, etc. -> can help to generate ideas
might give ideas of how the personality works
but, it’s inefficient -> would take too long to study many people in this way
(hundreds or thousands of people would need to be studied for this method)
also, doesn’t give a way to test ideas about personality
o Nomothetic approach: try to understand all people in terms of personality variables
By measuring many people, can see how variables are inter-related -> and can
test ideas about personality in general (not just for one person)
Basic Measurement Concepts
To test ideas about personality, we need to measure the personalities of many people, and then
analyze and compare the measurements
If we measure people on a characteristic, we (obviously) want our measurements to show which
people have higher and lower levels of the characteristic (e.g. musical ability)
We also want our measurements to show how big the differences are between people
o E.g. difference between “10” and “15” should mean the same thing as between “25”
If our measurements give meaningful differences between people, then we have “interval
scores” PSYC 2P25 – Personality and Individual Differences Sep. 10, 2012
With interval scores, we can calculate means, standard deviations, correlations, etc.
o Note: personality measurements rarely have a “true” or “absolute” zero score, so we
cannot compare scores in terms of ratios -> doesn’t make sense to say, e.g. that one
person is “twice” as nice/smart/lazy/nervous, etc.
When we measure psychological characteristics, we find that many (but not all) of them have a
continuous distribution (not categorical)
Usually, most people have levels closest to average, with few people at (each) extreme -> often
fairly close to normal distribution
The Correlation Coefficient (r)
To understand personality, we often want to find out how much a personality characteristic is
related to some other variable
o E.g. anoth