PSYC 2600 Lecture Notes - Lecture 2: Justin Bieber, Phineas Gage, Frontal Lobe
19 Jun 2018
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Week 2: Evaluation of Personality Measures
Reliability
- Precision
- The test needs to give the same results
Types of Reliability
1. Test-retest: the test gives the same scores over time, test one and test two correlate
(0.80 or higher)
2. Inter-rater: used with two or more raters (observation data)
The ratings should correlate
3. Internal consistency: a measure between different items on the same test, each item
should measure the same construct
Validity
- Accuracy
Types of Validity
1. Face: the extent to which a scale appears to measure what it is supposed to be
measuring (Face value- not deep)
2. Predictive/criterion: the extent to which the scale predicts the construct
Ex. if you are measuring happiness, someone scoring high in happiness on your test
should be happy
3. Convergent: the extent to which the measure correlates with other measures of the
same construct
4. Discriminant: the extent to which the measure doesn’t correlate- it is not supposed to
correlate, creates a negative correlation
Example: if you are measuring extraversion, a scale of outgoing should correlate, a scale
of shy should not
5. Construct: includes all of the other types of validity
Generalizability
- Do my findings apply to all people, some people, or no one?
Research Designs in Personality
Experimental Methods
- True experiment
- We manipulate a variable (change the level) and see if the outcome changes
find more resources at oneclass.com
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- If the outcome changes it means that there is a causal relationship
- All other variables have to remain constant
- Participants must be randomly assigned
Correlational Studies
- Identifies the type and strength of the relationship
Type: positive, negative, neutral
Strength: strong or weak- demonstrated by numbers (>0.8 is a strong correlation)
- The correlation coefficient can be anywhere between -1 and +1
- Correlation does not equal causation, a third variable can be causing the change
Case Studies
- Rare because they are costly, time consuming, and one person has to be extraordinary
to be examined
- Lots of detail
- The media conducts sensational case studies (ex. articles on Justin Bieber)
Example: Phineas Gage
- Suffered a severe brain injury when an iron rod pierced his skull
- Part of his frontal lobe was damaged
- His personality changed, he became irritable and unreliable
Disadvantages:
- Results may not be generalizable to other people
- Used to generate a hypothesis
When to Use What Design
- Each design has strengths and weaknesses
- If we had the money and time we would do two or three methods
Traits and Taxonomies
- When we are talking about traits and taxonomies we’re trying to create a cohesive
method of all of the adjectives used to describe people
- Some adjectives refer to traits that are consistent, some capture one aspect of
behaviour that may not occur very often
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- We want to determine which ones are the overarching adjectives- the best descriptors
of people
Trait-Descriptive Adjectives
- Give us an external picture of someone
Three Questions Guiding Trait Research
1. What are traits?
2. How can we decide which traits are the most important?
3. Can we organize the traits in a way that makes sense?
(taxonomy of traits= organization, a system)
What is a Trait?
1. Traits as internal causal properties: traits make people do things
Example: if someone is extraverted, the extraversion makes them friendly
2. Traits as external causal properties: the environment needs to be considered
Traits as Internal Causal Properties
- Traits are internal, they represent our inner thoughts and motivations
- We carry traits inside of us
- Desires and needs- they cause us to act in a certain way
- Doesn’t take into account the environment
- Traits can be dormant, they aren’t expressed all the time
- Behaviour is explained using traits, ruling out all other influences
Example: you can have the desire to socialize when you are with people, and when you are
not with people (dormant)- the desire of socializing with people, causes people to act either
talking to people, or to find a social situation
Gina has an underlying need to win- this an urge, there is an inner urge, the urge is
triggered by prizes for top grades (reinforcement), the resulting behaviour is studying hard
Traits as Purely Descriptive Summaries
- We can’t draw conclusions about the cause, we are just describing people
- Opens the door to other causes of behaviour
- The environment can be a strong illicitor of behaviour
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
The test needs to give the same results. Types of reliability: test-retest: the test gives the same scores over time, test one and test two correlate (0. 80 or higher) Inter-rater: used with two or more raters (observation data) Internal consistency: a measure between different items on the same test, each item should measure the same construct. Types of validity: face: the extent to which a scale appears to measure what it is supposed to be measuring (face value- not deep, predictive/criterion: the extent to which the scale predicts the construct. Example: if you are measuring extraversion, a scale of outgoing should correlate, a scale of shy should not: construct: includes all of the other types of validity. We manipulate a variable (change the level) and see if the outcome changes. If the outcome changes it means that there is a causal relationship. Identifies the type and strength of the relationship.
