DOCTORS' LOUNGE
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WHAT, ME WORRY? AUTHOR Mary Barry, MD
R
eading about the different types
of personalities always makes me
squirm a little bit inside. I believe I
first subscribed to Psychology Today
back in the late ‘60s, falling prey to
those tear-out ads that promised
years and years of subscriptions for
only 99 cents. (I defy you to tell me that you,
too, did not also get 12 records for $0.99 and then pay enormous
sums for shipping for the five other required albums.)
Being put under the psychological microscope, even theoretically,
is interesting, but unnerving. We might tend to paint ourselves
too optimistically, claiming a better character than we have, or too
pessimistically, enjoying the novelty of darker and darker shades. We
might underestimate our ignorance and overestimate our acumen.
We might shy away from questions that are too probing, as in “none
of their damn business.” I think the first time I actually had to take
such a test in earnest was in a sociology class at Spalding College,
a class I hated. Doctors take a lot of tests. I remember that on our
psychiatric rotation as junior students we took a sort of MMPI,
then studied it.
I was interested to read about not only the Five-Factor Model
(FFM) of organizing personalities, but also the newly described Four
Personality Types (Martin Gerlach et al in Nature Human Behavior
vol. 2, 735-742, 2018). His article, “A Robust Data-Driven Approach
Identifies Four Personality Types Across Four Large Data Sets,”
is an exercise in reading statistics. A typical sentence: “Although
these results suggest that the solution of the GMM with Nc=13
severely overfits the data, a detailed analysis on cluster solutions
with different assumed Nc shows a nontrivial dependence of the
cluster positions on the number of surmised clusters Nci; that is,
fitting with only Nc=4 clusters yields a solution that fails to identify
most of the meaningful clusters.”
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LOUISVILLE MEDICINE
I will not attempt to translate that sentence. After a lot of other
sentences of that ilk, it becomes clear that the authors took huge
databases of people who answered personality questionnaires –
100,000 to 500,000 respondents - and their analysis showed that
we fall into four main groups of personality types.
But first, the Five Factor Model, named by the psychologists
Robert McCrae and Paul Costa, authors of the 1978 book
Revised Neo Personality Inventory, characterized these traits/
domains as neuroticism, extraversion, openness, agreeableness and
conscientiousness as the basic descriptors of personality. Dr. Gerlach
is a physicist by trade, educated in Dresden, Germany, whose
professional interest is “to understand the dynamics of different
complex systems by applying mathematical models to statistical
analysis of experimental data on human behavior and interaction.”
He works with other researchers in the lab of Dr. Luis Amaral at
Northwestern. He notes in his article that these five domains “have
been reliably identified by empirical data across different languages
and cultures” and have successfully “predicted patterns of behavior
in well-being, mental health, job performance and marital relations.”
He notes that the previous classification of personality types as
“resilient” or “over controlled” or “under controlled” is based on
Freudian Theory and has repeatedly failed statistical tests of validity.
Results are not replicable because of the small sample sizes in the
studies, he says, ranging up to only a thousand people.
Therefore, he used four different datasets (each up to 500,000
people) of web-based questionnaires collected at different times
from different countries, with different ages and genders. These
questionnaires also use different scales to measure the FFM previously
mentioned. He designed a way to make a reliable statistical cluster
based on the questionnaires, which were themselves developed on
the platform of the multiply-revised Neo-Personality Inventory.
His method of analysis identifies and scores the FFM traits
as present in four definite clusters of personality types: average,