Unit 0: Science Practices
:
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Learn why psychology is a science and how psychologists ask and answer
questions.
Gain the foundational skills to think critically about psychology research
and data.
Begin to develop the tools to develop psychological arguments.
What is
Psychology?
Psychology
• Scientific study of behavior and mental
processes
• Behavior: any action or reaction of a living organism
that can be directly observed
• Mental Processes: Internal processes such as
thinking, feeling, and desiring that can only be indirectly
observed
Mental processes are the internal operations of the mind that are not directly
observable. These include:
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Cognition: Mental activities related to thinking, knowing, and remembering. This
involves perception, memory, problem-solving, decision-making, and reasoning.
Emotion: Internal experiences related to feelings, which can influence behavior
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and thought patterns.
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Perception: The process of organizing and interpreting sensory information to
understand the environment.
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Motivation: The internal drives and needs that direct behavior towards
achieving goals or satisfying needs.
Modern Perspectives
of Psychology
Biological
• All your feelings and
behaviors comes from
brain: genetics, body
chemistry (hormones,
neurotransmitters),
brain’s structure
Evolutionary
• Focuses on Charles Darwin’s survival
of the fittest, natural selection
• Mental processes exist because they
serve an evolutionary purpose – they
aid in survival, reproduction
Psychodynamic
• Originated by Freud
• Unconscious mind
• understanding ourselves in
terms of our unconscious
desires and motives and
memories
Freud (1856-1939)
Behavioral
• Focus on scientific investigations on
observable behaviors and how they are
learned and reinforced
• Attempt to change behaviors
that impair our living
• Pavlov, Watson, and later Skinner
Cognitive
• Focus on how we think
(Examines thinking & behavior
in terms of how we interpret,
process, and remember
environmental events)
• Attempt to change the way
you think
Sociocultural
• Focus on how culture, religion, ethnicity,
gender, community, even income level
effects your behavior.
• Even within the same high school, behavior
can change within different subcultures
Humanistic
• Emphasizes role of motivation,
free will, potential for growth
• We strive to be the best we can
be, “self-actualization”.
• Happiness is defined by the
distance between our “selfconcept” and “ideal self”.
Biopsychosocial
• model of explaining illness and
treatments by examining a
patients biology, personality
and social influences
• Recognizes diseases are both
biological and physiological but
the perception of the illness
or condition is social
Hurdles that Skew
our Logic
Hindsight bias
False Consensus Effect
Confirmation Bias
Overconfidence
We like to think that we make rational decisions.
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The truth is - our brains take shortcuts all the time
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We can’t pay attention to every detail of every decision
Cognitive biases are systematic errors in thinking. These biases are
like shortcuts our brains take to make processing information
easier and quicker, but they often lead us to incorrect conclusions
or irrational decisions.
Hindsight Bias
The tendency to believe,
after learning the
outcome, that you knew
it all along.
ex. Post-game critics
False Consensus
The tendency to assume
that one's own opinions,
beliefs, attributes, or
behaviors are more
widely shared than is
actually the case
Confirmation Bias
Tendency to search for, interpret, and remember
info that confirms our preexisting beliefs or opinions.
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Example: If you strongly support a political party, you're
more likely to favor news outlets and opinions that align with
your views and ignore those that don't, reinforcing your
existing beliefs.
Why It’s Misleading: It skews our perception of reality, leads to
poor decision-making, and can cause polarization by creating
echo chambers where opposing viewpoints are disregarded.
Overconfidence
Tendency to overestimate your knowledge
and/or ability
- 82% of U.S. drivers consider themselves to be
in the top 30% in terms of safety.
- 81% of new business owners felt they had an
excellent chance of their businesses
succeeding. When asked about the success
of their peers, the answer was only 39%.
Illusory Correlation
Tendency to believe that
variables have a
relationship where none
exists
- Superstitions and
pregame rituals
The Barnum Effect
The tendency for people to accept very
general or vague characterizations of
themselves and take them to be accurate.
The Science of
Psychology
The scientific attitude curiosity + skepticism +
humility - prepares us to think
harder and smarter. This
thinking style, called critical
thinking, examines
assumptions, appraises the
source, discerns hidden
biases, evaluates evidence,
and assesses conclusions.
0.1-3 Explain how critical thinking feeds a scientific attitude, and smarter thinking for everyday life.
Critical thinking is the engine that drives the scientific attitude.
● Thinking that does not automatically accept arguments and
conclusions. Rather, it examines assumptions, appraises the
source, discerns hidden biases, evaluated evidence, and
assesses conclusions
Research
Methods
* Remember, psychology is
a science! Thus it is based in
research.
Allows researchers to achieve 4 goals
1. Describe psychological phenomena to
understand them better
2. Predict what will occur in the future
3. Control factors that are believed to cause
a phenomenon
4. Explain why the phenomenon occurs
0.3-1 Describe how theories advance psychological science.
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Theory: A theory in psychology is like a roadmap
that helps us organize our observations and make
predictions about behavior. It's a structured
explanation based on principles that guide research
and understanding.
Guiding Research: Theories provide a starting point for exploration.
Example: Psychologists might have a theory that social media
usage has a negative effect on adolescents.
Why It’s Important: It provides a framework for understanding and
predicting phenomena.
Everyone Says Social Media Is Bad for Teens. Proving It Is
Another Thing. New York Times, 2023
Hypothesis
• Testable prediction about the relationship
between 2 variables
• A variable is anything that can vary
among participants in a study.
• Example: Participating in class leads to
better grades than not participating.
Hypothesis
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Testable prediction about the
relationship between 2 variables
If__________, then______
Example: "Teenagers who spend more than three
hours a day on social media will report higher
levels of anxiety and depression compared to
those who spend less than one hour a day."
Why It’s Important: It guides research by
providing a clear statement to be tested.
Association between Social Media Use and Depression among U.S.
Young Adults, Lin et all - visualized by Clearvue Health
https://www.clearvuehealth.com/b/social-media-depression/
HYPOTHESIS
People with high-stress levels will be more likely to
contract a common cold after being exposed to the virus
than people who have low-stress levels.
Falsifiable
Rich
Poor
Operational Definitions
• Explain what you mean in your hypothesis.
• How will the variables be measured in “real
life” terms.
• Allows for repetition of the experiment
What do you mean by ...
Types of Research
• Qualitative Research:
•
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Research where the data is not in the form of numbers
Descriptive Methods –case studies, surveys or naturalistic observations
• Quantitative Research:
•
•
•
Deals with numerical data or data that can be turned
into numbers
Correlational Studies- associate different factors or variables.
Experimental Methods- manipulate variables to establish causeand-effect relationships.
A Good Study Needs 3 Things…
1. Replicate “Repeat”:
• Repeat methods from
previous experiment to see
if you get same results
• Confidence in findings!
A Good Study Needs 3 Things…
2. Reliability “Consistency”:
• If the study were to be
done a second time, it
would yield the same results
3. Validity “Legitimacy”:
• Credibility of the research:
measures what it is
supposed to measure
Reliability = CONSISTENCY
Validity = ACCURACY
Reliable, but
Unreliable and hence
not valid
not valid
Reliable and valid
PEER REVIEW
Evaluation by members
in the field
Sampling
• Identify the population you want to study.
•
Defines the group to which the research findings will be generalized
• The sample must be representative of the
population you want to study.
• Sampling bias- sample is collected in a way that some
members of the target population are less likely to be included.
• Representative sample- A sample that has
characteristics that are similar to those in the population
(enhances the generalizability)
• GET A RANDOM SAMPLE
Sampling
Random Sample: Each
member of the population
has the same chance of
getting selected into sample
- Reduces bias & increases
representativeness
Random Assignment: Ensures
all members have an equal
chance of being placed in
either control or experimental
group(s)
Want understanding, in detail, of the experience of
their research participants
Case Study
• In-depth study of a single person, group, or
rare phenomenon
• Tells us a great story…but is just descriptive
research.
Case Study
(+) Provides detailed analyses of
new/rare phenomena
(-) Not representative of whole
population (can’t generalize)
Survey Method
• Most common type of study in psychology
• Questionnaires or interviews to ask a large # of
people questions
• Measures correlation
• Cheap and fast
• Need a good random sample
Social Desirability Bias
• Wanting to Look Good
• Social desirability bias occurs when
respondents give answers they think are
socially acceptable rather than truthful.
• Example: Underreporting smoking habits in a
health survey.
Survey Method
(+) tremendous amount of data on a
very large group of people
(-) Distorted results because of poorly
phrased questions & response biases
Naturalistic Observation
• Watch subjects in their natural
environment.
• Do not manipulate the
environment.
• Realistic picture of how behavior
occurs, genuine
• The bad is that we can never really
show cause and effect.
Naturalistic Observation
(+) Provides descriptive data
about behavior with wide
applicability
(-) Loss of experimental control
Meta-Analysis: Combining Results
Meta-analysis statistically
combines the results of multiple
studies on the same topic.
Example: Analyzing numerous
studies on the effectiveness of a
specific therapy.
Why It’s Important: It increases
statistical power and
generalizability.
From a University
Presentation Showcase
(Graduate Poster Galley) at
Eastern Kentucky University:
https://encompass.eku.edu/s
wps_graduategallery/46/
Correlational Method
• Correlation expresses a
relationship between two variable.
• Does not show causation!
• Studies do not involve manipulation
of variables (non experimental)
• Uses scatterplot
•
Example: As more ice cream is eaten, more
people are murdered.
If students missing the
most classes get lower
grades, the suggestion is
that there is a
relationship between
attendance and overall
performance
THIRD VARIABLE/THIRD VARIABLE PROBLEM
An undiscovered causative variable
CORRELATIONAL
CORRELATIONALSTUDIES
STUDIES
Correlation Coefficient
• A number that measures the strength of a
relationship.
• Range is from -1 to +1
•
The relationship gets weaker the closer you get to zero.
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Strong relationship → # closer to +1.00 or to -1.00
weaker the relationship → # close to 0
CORRELATIONAL
COEFFICIENT
Strong
-1.0
R
Weak
-0.5
NEGATIVE CORRELATION
STRENGTH
OF
RELATIONSHIP
Weak
0.0
+0.5
POSITIVE CORRELATION
+1.0
Types of Correlation
• Positive Correlation
• The variables go in the SAME direction
Studying and grades hopefully has a positive correlation.
• Negative Correlation
• The variables go in opposite directions
Heroin use and grades probably has a negative correlation.
Positive Correlation
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Positive Correlation: 2
variables increase and
decrease together
Example, the relationship
between time spent
exercising and fitness level
Avoid thinking of a positive
correlation as indicating a “good
relationship”
Negative Correlation
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Negative Correlation As 1
variable increases, the other
decreases (opposite
directions)
Example, as the
temperature decreases, the
amount of clothing people
wear generally increases
Avoid thinking of a negative
correlation as indicating a “bad
relationship”
CORRELATIONS
Colors in a rainbow
Grades
Crime rates
SCATTERPLOT
Ice cream sales
Absenteeism
Shoe size
POSITIVE
NEGATIVE
NO CORRELATION
When one variable increases, the
other decreases.
No relationship between the two
variables can be seen.
When one variable increases, the other
increases OR when one variable
decreases, the other decreases.
WHICH DEMONSTRATES A STRONGER RELATIONSHIP?
-.70 OR +.65?
+.08 OR +.33?
+.62 OR -.89?
-.54 OR +.21?
WHICH DEMONSTRATES THE STRONGEST RELATIONSHIP?
Correlational Method
(+) Useful as a pointer for further,
more detailed research
(-) Cannot assume cause and effect,
strong correlation between variables
may be misleading.
Experimental Method
• Tests a hypothesis and establishes causation
(Looking to prove causal relationships)
•
(1) Manipulating variables
• (2) Determines cause & effect relationships
Independent Variable
• The factor that the
experimenter manipulates
•
The if part of hypothesis
identifies IV(Ex: Amount of
homework, amount of
chocolate, amount of
coffee)
If there is a drug in an experiment, the drug
is almost always the independent variable.
Dependent Variable
• The variable that is being
measured in the experiment
• It is dependent on the
independent variable.
• The then part of the hypothesis
identifies DV
The dependent variable would be the effect of the drug.
Experiments aim
to manipulate an
independent
variable, measure
the dependent
variable, and
control all other
variables.
Other Confounding
Variables and Bias
Beware of Confounding
Variables
• The object of an experiment is to prove that
A causes B.
• A confounding variable is anything that
could cause change in B, that is not A.
CONFOUNDING
VARIABLE
Cause
Uncontrolled variable
Affects outcome
Effect
Control vs. Experimental Group
Control Group
“Comparison Group”: No
treatment/no effect.
Used to control for
possibility that other
factors might cause the
effect that is being
examined
Experimental Group: Group
that is exposed to
Independent variable,
receives the experimental
manipulation
Random Assignment
• Once you have a random sample, randomly
assigning them into two groups helps control
for confounding variables.
• Experimental Group v. Control Group.
• Group Matching
Hawthorne Effect
• But even the control group
may experience changes.
• Just the fact that you know
you are in an experiment
can cause change.
PLACEBO
Inert substance
Placebo effect
Experimenter Bias
• Another confounding variable
• Occurs when a researcher’s expectations or
preferences about the outcome of a study
influence the results in a “hoped-for”
direction
• Not a conscious act.
• Double-Blind Procedure.
The Power of Expectations (Experimenter Bias)
Self Report Inventories (Surveys): The Pros and Cons
Experimental Method
(+) Easier to comment on cause
and effect.
(-) The artificiality may produce unnatural
behavior that does not reflect real life
There is less control over extraneous
variables that might bias the results.
Method
Purpose
Conducted
Manipulated
Advantages
Disadvantages
Descriptive
To provide
observe &
record behavior
In any setting
Nothing
Can be cheap and
easy
Can inspire ideas
for future research
Can be time
consuming and
costly
Cannot
manipulate
factors
Presence of
observer may
skew data
Correlational
To detect
naturally
occurring
patterns/
relationships
In any setting
Nothing
Can inspire ideas
for future research
Can lead to false
assumptions
Experimental
To explore cause
& effect
In a laboratory setting
or controlled
environment
Variables in
question
Can establish cause
and effect
Factors can be
controlled
Can be time
consuming and
costly
Results can be
from outside
variables
Statistics
Statistics
• Statistics allow psychologists to
organize data, describe data, and
make inferences based upon data.
• Must use a common language so we all
know what we are talking about.
Statistical Reasoning
Descriptive Statistics:
Techniques for
organizing/summarizing data
sets
(Ex: Mean, median, mode)
Inferential Statistics Allow you
to interpret data/draw
conclusions
(ex: standard deviation)
Descriptive Statistics
• Simply a way to
describe sets of data
• Frequency distribution is
a way to summarize
data in a meaningful
way
• Measures of central
tendency are also useful
Measures of Central Tendency
• A single score that represents a whole set of
scores
Central
Tendency
Mean
Median
Mode
Average
Middle number
Most frequent
Most impacted
by outliers
Central Tendency
• Mode: The most frequently occurring score in
a distribution.
• Mean: The arithmetic average of scores in a
distribution obtained by adding the scores
and then dividing by their number.
• Median: The middle score in a
rank-ordered distribution.
Central Tendency
• Mean, Median & Mode
• Watch out for extreme
scores or outliers.
Let’s look at the salaries of the
employees at Dunder Mifflen
Paper:
$25,000-Pam
$25,000- Kevin
$25,000- Angela
$100,000- Andy
$100,000- Dwight
$200,000- Jim
$300,000- Michael
The median salary looks good at $_____________.
The mean salary also looks good at about $ _______
But the mode salary is only $___________.
REGRESSION TO TOWARD THE MEAN
The tendency of outliers to be followed by data points that are closer to the
mean.
Measures of Variation
• A single score that presents information about
the spread of scores in a distribution
Normal Distribution
• In a normal distribution, the mean, median
and mode are all the same.
IQ follows
a normal
distribution
Distributions
• Outliers skew distributions.
• If group has one high score, the curve has a
positive skew (contains more low scores)
• If a group has a low outlier, the curve has a
negative skew (contains more high scores)
Other Measures of
Variability
• Range: distance from highest to lowest scores.
• Standard Deviation: the variance of scores
around the mean.
• The higher the variance or SD,
the more spread out the
distribution is.
•
Do scientists want a big or small SD?
Standard Deviation
Percentile Rank
Percentile Rank: The percentage
of scores in a distribution that a
particular score falls above
●
90 percentile, 90% of the scores are the
same or below yours
Percentage of scores falling between pairs of
standard deviations around the mean
Standard Deviations
Around the Mean
Percentage of Scores
-1, +1
68.26%
-2, +2
95.44%
-3, +3
99.72%
Z Scores
• A unit that measures the distance of one
score from the mean.
• A positive z score means a number
above the mean.
• A negative z score
means a number
below the mean.
Inferential Statistics
• The purpose is to discover whether the
finding can be applied to the larger
population from which the sample was
collected.
• P-value= .05 for statistical significance.
• 5% likely the results are due to chance.
Statistical Significance
• The P-Value: The probability of
concluding that a difference exists when
in fact this difference does not exist
• Statistical Significance: A difference not
likely due to chance (5% of the time or less)
• The smaller the P-value, the more significant
the results
Ethics in Research
Ethics in Research
Ethics: The correct rules of conduct and
moral principles necessary when carrying
out research
●
Humans and animals involved in studies
must be treated according to the highest
ethical standards
Ethics in Research
Identical triplets Eddy Galland
(from left), David Kellman and
Bobby Shafran were separated
at birth and adopted by
different families. When they
reconnected at age 19, they
discovered "incredible
similarities that couldn't be
accounted for by chance."
It turns out they were split up as part of a scientific experiment
run by a prominent ... New York based psychiatrist looking into
nature versus nurture and the relative importance of heredity
versus environment
GOVERNANCE
AMERICAN PSYCHOLOGICAL ASSOCIATION
Governing body for psychology
FEDERAL REGULATIONS
Harm to self or others
INSTITUTIONAL REVIEW BOARD (IRB)
Local
Animal Research
• Clear purpose
• Treated in a humane way
• Acquire animals legally
• Least amount of suffering possible.
Human Research
• No Coercion- must be voluntary participation
• Informed consent
• Confidentiality
• No significant risk
• Protection from harm
• Must debrief