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Lecture 3

PSYC 2P25 Lecture Notes - Lecture 3: Trait Theory, Lexical Hypothesis, Factor Analysis

Course Code
Michael Ashton

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PSYC 2P25 Sept. 24, 2012
Personality Structure
When assessing people’s personalities, it isn’t feasible to measure ALL traits reliably, it would
take too long
But, if you decide to measure only a few traits, some of them might be very similar and you
might completely miss a lot of important traits
But if we could categorize personality traits into a few groups of related traits, then we could
assess a few traits from each group and thereby summarize people’s personalities thoroughly
and efficiently
Finding basic trait categories would also help to organize research on personality (every
researcher would measure similar set of traits) and [maybe] give clues about the causes and
functions of personality itself
How to identify the basic trait categories?
o Examine correlations among many traits and find a few (unrelated) groups of strongly
correlated traits:
Use “factor analysis”
Numbers show how clearly variables “belong” to that factor
High loading on factor means high rs with other variables in same factor
Usually, results aren’t obvious ad you actually need to do FA
When using FA to find major dimensions of personality, you need a complete list of personality
traits (if some traits are missing, then you might miss a factor completely)
o Get list through the lexical approach
The Lexical Approach
Two ideas it’s based on:
o 1) a few basic personality traits (“dimensions”) will each be seen in many specific, subtly
distinct traits
o 2) people want to talk about each other’s personalities, and invent many adjectives to
describe people on those may traits
So, we could measure people on personality trait adjectives (using dictionary list), and then do
factor analysis to find the basic dimensions of personality
Using the lexical hypothesis
o 1) get list of familiar personality adjectives
o 2) get self- or observer ratings of many people (multi-point scale)
o 3) find rs among adjectives, and factor analyze them
o 4) interpret each factor by finding common meaning of its adjectives
Results of lexical studies
o Idea of LH is old (Galton, 1884), but 1st lists of personality adjectives in 1930s
o Cattell (1943) did early FA study using adjective ratings
Only used 35 adjectives (from list of 4500)
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