Project 1:

1
Project 1

• Personality and Physical Health

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Introduction

• It is widely believed that an individual's
  personality can contribute to his or her health
  status and responses to illness.
• It is not easy to demonstrate that there is a
  relationship, or to identify explanations for the
  relationship when it does exist.

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Smith (2006)

• Research has identified several personality
  characteristics which are associated with health
  outcomes
• Risk factors
• Type A behavior (especially hostility)
• Negative affect
• Neuroticism
• Associated with better health
• Optimism
• Conscientiousness

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Smith (2006)

• What can we conclude from these associations? A
  few problems with drawing conclusions
• Construct validity of some personality scales and
  health measures may be in question
• We dont know what mechanisms underlie the
  associations
• For instance, could personality characteristics
  influence health habits, such as smoking, which
  in turn affect health status?
• Smith identifies several possible models of
  mechanisms that link personality to health

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Deary Der (2005)

• Some research has identified another variable
  associated with health outcomes People with
  lower IQ tend to die younger than those with a
  higher IQ

• Mechanisms that might explain this association
• Low birth weight or other developmental health
  problems may prevent cognitive development and
  contribute to lower IQ
• Higher IQ might contribute to better health
  behaviors
• Higher IQ might be predictive of better
  socioeconomic status, thus safer environments
• Higher IQ might be related to a greater
  efficiency of information processing

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Deary Der (2005)

• Higher IQ might be related to a greater
  efficiency of information processing?
• Cognitive efficiency could be measured by
  reaction time, which is not knowledge- or
  culturally-specific in the way that IQ tests are.
  
• Reaction time tasks might also be associated with
  bodily integrity
• In fact, this hypothesis that reaction time might
  explain the relationship between IQ and longevity
  was the only one that their data supported

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Project 1 Goals

• To investigate the questions explored by Smith
  (2006) and Deary Der (2005)
• Broad research question Are personality or
  reaction time measures related to a person's
  health, and if so, what model best explains the
  relationship?
• It will be up to you to develop a more precise
  research question

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Data for project 1 were gathered on the
following variables

• Dependent Variables (which we will be correlating
  with each other) (note that because we did not
  manipulate any of these, we do not have any
  independent variables in project 1)
• Five personality factors taken from the
  International Personality Pool
• Simple reaction time task intended to measure
  efficiency
• Choice reaction time task intended to measure
  efficiency
• Health behaviors inventory (Wellness Maintenance
  and Enhancement, Accident Control, Traffic Risk,
  and Substance Risk)
• Current health status (Days Missed Due to
  Illness, Other Days of Illness, Susceptibilty to
  Minor Illness, Susceptibilty to Major Illness,
  and Time to Recover)
• GPA
• The specific items are available here if you
  would like to examine them more carefully.

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Your first task

• Read the Smith (2006) and Deary Der (2005)
  papers to get a more thorough understanding of
  the theories and research findings.
• Use these articles to come up with two or three
  hypotheses that could be tested using the
  variables we measured. Which personality
  characteristics might be related to which health
  variables?

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Your task, cont

• There are many variables available to examine in
  Project 1 this gives each of you some
  flexibility. However, your hypotheses must
  conform to the following
• They should be clearly motivated by the prior
  theory. Using research from the articles, you
  will need to justify why you hypothesize the
  relationships.
• They must involve predicting health outcomes
  (i.e., as opposed to simply hypothesizing that
  two personality characteristics are related to
  each other)
• At least one of your hypotheses must examine
  potential mediating variables.

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What is a mediating variable?

• If we find a relationship between a particular
  personality characteristics and a particular
  health measure might this be a causal
  relationship?
• An understanding of causality can be aided by
  looking for mediating variables - other variables
  that might account for the observed correlation.
  You should review the handout on mediating
  variables and partial correlations.

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What is a mediating variable?

• If there is a correlation between X and Y, then
  there are several possible conclusions
• X may be causing Y
• Y may be causing X
• Or an additional mediating variable Z may be
  causing both X and Y, accounting for the
  relationship between the two.
• Or, a combination of any and all of these
  conclusions may be true (i.e. Z may act as a
  partial mediator)
• You can test for the presence of mediating
  variable by examining partial correlations. On
  the Tuesday after the exam, well go over how to
  do this (and all other relevant tests for project
  1) in SPSS.
• The concepts of mediating variables and partial
  correlations are very important when interpreting
  correlational data.

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More on mediating variables

• (Ilana doesnt know how to make pretty diagrams
  in powerpoint)
• What may mediate the relationship between weight
  and reading score?
• Between ice cream sales and drowning?
• Between birth order and IQ?