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UNIT 1 NOTES AP PSYCHOLOGY

What is Psychology? Psychology is the scientific study of behavior and mental processes Scientific? Not just common sense or guesses Psychology

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Page 2: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

What is Psychology? Psychology is the scientific study of behavior and mental

processes Scientific?

Not just common sense or guesses Psychology uses the scientific method Scientific Method is careful observations and the experimental

testing of hypothesis Behavior – what people do on the outside Mental Processes – What is going on inside someone's

head. We call this cognition. Psychology includes the study of both humans and

animals

Page 3: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Approaches to the field of Psychology

1. Biological

2. Evolutionary

3. Behavioral

4. Cognitive

5. Psychodynamic

6. Humanistic

7. Social

Page 4: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

1. Biological Psychology Investigates the biological basis of human

behavior, thoughts and emotions. Looks at how the following biological mechanisms effect your behavior and mental processes.BrainNeurotransmittersHormonesDrugs (both legal and illegal)Gender differences in brain structure and

function

Page 5: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

2. Evolutionary Psychology Asks the question: How did our species get to be the

way we are?Language – Why do we talk?Altruism – Why are we nice to each other?Sexual attraction / mate selection – Why are some people

considered beautiful? Answers these questions by looking at what would

most help us pass on our genetic code. Very concerned with reproduction!

Page 6: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

3. Behavioral

This approach only studies observable human behavior focusing on how we learn, react and manipulate our environment. 

We learn observable responses through conditioning or by trying to get rewards/avoid punishments.

Mind is a BLACK BOX. Can’t see it? Don’t study it. Big names

Pavlov – Dogs Watson – Little Albert Skinner – Operant Conditioning

Page 7: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

4. Cognitive Psychology

School of psychology that studies mental processesThinking, feeling, remembering, making decisions

and judgments Studies how we encode, process, store, and

retrieve information. Studies behavior and makes inferences

about the mental processes behind the behavior

Thanks to new technologies like CAT scans, MRIs and fMRIs, we can open the black box.

Page 8: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

5. Psychodynamic Psychology

Personality theory that says behavior springs from unconscious drives and conflicts

Unconscious is a dynamic cauldron of primitive drives, forbidden desires and nameless fears

Psychoanalysis – patient lies on a couch and recounts dreams and conducts free association.

Sigmund Freud

Page 9: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

6. Humanistic Psychology School of psychology that emphasizes

nonverbal experiences and altered states of consciousness as a means of realizing one’s full human potential

Importance of love, belonging, human potential, and self-esteem.

Abraham Maslow Not mainstream, more a cultural and

spiritual movement.

Page 10: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

7. Sociocultural Psychology

Study of how people influence one another Topics include:

First impressionsInterpersonal attractionAttitude formationPrejudiceBehavior in a groupObedience to Authority

Some Applications include:Support groupsFamily TherapySensitivity Training

Page 11: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Careers in Psychology

1. Clinical and Counseling

2. Developmental

3. Educational

4. Experimental

5. Personality

6. I/O (Health, Sports, Motivation)

7. Personality

8. Psychometric

9. Social-Psychology

Page 12: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

1. Clinical and Counseling Psychology

About 50% of all Psychologists Counseling psychologists deal with “normal” problems,

such as stress caused by career change or marital problems

Counseling psychologist’s focus more on the psychologically healthy individual where clinical focuses on individuals with serious mental illness (e.g. schizophrenia).

Clinical psychologists are concerned with diagnosis and treatment of psychological disorders

Split time between treatment and researching the cause of psychological disorders and the effectiveness of different types of psychotherapy and counseling.

Page 14: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

3. Educational Psychology

School Psychologist psychological evaluations consult with school personnel in relation to

students’ learning, behavior, and environments

they are trained to look at the effectiveness of academic programs, classroom agendas, and treatment interventions, which assists in the development of specific interventions.

Page 15: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

4. Experimental Psychology Design research experiments May or may not have a direct impact on the

treatment of patients Animal subjects Drug trials

Page 16: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

5. Human Factors

The science of understanding the properties of human capability (Human Factors Science).

The application of this understanding to the design, development and deployment of systems and services (Human Factors Engineering).

It can also be called ergonomics.

Page 17: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

6. Industrial and Organizational Psychology Study of psychological principles in

industry and business Examples

Selecting and training personnelProductivity improvementOptimizing working conditionsManaging the impact of automation on

workers

Page 18: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

7. Personality Psychology Study of how people differ from one

another on traits such asOpennessConscientiousnessExtraversionAgreeablenessNeuroticism

Page 19: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

7. Psychometics

Test creation Validity Reliablity Culture fair Statistics

Page 22: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

GROWTH OF PSYCHOLOGY

Page 23: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Psychology’s Roots Are in Philosophy

Prescientific Psychology Do you have a soul?

Is the mind connected to the body or distinct?

Are ideas inborn or is the mind a blank slate filled by experience?

Page 24: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Prologue: Psychology’s Roots

Page 25: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Psychology’s Roots

Psychological Science Is Born Empiricism –

Knowledge comes from experience via the senses

Science flourishes through observation and experiment

Page 26: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Psychology’s Roots

Wilhelm Wundt opened the first psychology laboratory at the University of Liepzig (c. 1879)

Page 27: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Psychology’s Roots

Wundt’s significance? By insisting on

measurement and experimentation he moves Psych from Philosophy to Science

Page 28: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Psychology As Science

Psychologists use the scientific method Steps to the scientific method

Collect dataGenerate a theory to explain the dataProduce a testable hypothesisSystematically test the hypothesis

Page 29: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Psychology’s Roots

Bradford Titchener Emulates the analysis

of compounds by looking at atoms

Structuralism used introspection (looking in) to explore the elemental structure of the human mind

Page 30: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Psychology’s Roots

Structuralism – School of psychology

that stressed the basic units of experience (physical sensation, feelings, and memories) and the combinations in which they occur.

Study these ‘atoms of experience’ to get the structure of the mind

Page 31: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Prologue: Psychology’s Roots William James Rejects

Structuralism Influenced by Darwin Functionalism –

theory of mental life and behavior that is concerned with how an organism uses its perceptual abilities to function in its enviroment.

Page 32: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

The Growth of Psychology Sigmund Freud: Psychodynamic

psychologyBehavior results from forces at work within

the individual, often at an unconscious level○ Sexual and aggressive drives

Late 1800sLasting Impact of the fieldHard to prove or disprove scientifically

Page 33: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Return to the observable in the early 1900s John B. Watson: Behaviorism

Studied only observable behaviorsExpanded upon the work of Pavlov

B.F. Skinner: Behaviorism revisitedExpanded behaviorismViewed the mind as a “black box” that was

irrelevant

Page 34: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

The Cognitive Revolution

The precursors to cognitive psychology:Gestalt psychology

○ Study of how we perceive objects as whole patterns

○ Therapy that wishes to treat the whole personHumanistic psychology

○ Emphasizes realization of full potential○ Recognizes importance of love, self esteem,

belonging, and self-actualization

Page 36: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

New Directions in Psychology Evolutionary psychology

Studies the adaptive value of behaviors and mental processes

Positive psychologyStudy of the subjective feelings of happiness

and well-beingFocus is on positive attitudeResponse away from victimization

Page 38: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Psychology’s Big Issues Nature-nurture controversy

Are we a product of innate, inborn tendencies controlled by our genetic make-up?

Are we a reflection of experiences and upbringing? Person–Situation

Is behavior caused by factors inside the person or outside? Stability–Change

Are behavior patterns learned in childhood permanent or do people change over time?

Diversity-Universality How am I like every person, like some people, and like no one else?

Mind–Body What is the relationship between the mind and the body?

Page 39: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

AP PSYCHOLOGY

Research Methods: Experiments

Page 40: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Research Methods – Essential Methods

How do psychologists use the scientific method to study behavior and mental processes?

What are the strengths and weaknesses of the different research methods?

How do psychologists draw appropriate conclusions about behavior from research?

Page 41: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Be curious. Question your

world.

Collect data using DESCRIPTIVE

Research

Form a Hypothesis

Conduct more research

Relationship? Causation?

Case Study

Naturalistic Observation

Survey

CORRELATION EXPERIMENT

Create testable

operational definitions

Doesn’t support the hypothesis

Supports the hypothesis

Create a Theory

Continue to retest

Use this to predict and

explain the world

Scientific Method

Page 42: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Be curious!

1. Does involvement in HS athletics improve academic performance?

2. Does excessive texting impede face-to-face relationships?

3. Does personality influence musical preferences?

4. Do ads portraying unrealistic body types reduce the self-image of the viewer?

5. Does student consumption of caffeine in the morning improve first period grades?

6. Does gamification of the classroom improve increase student engagement?

Page 43: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

7. Does a community service requirement positively or negatively impact student opinions of community service?

8. Does HR increase communication in a large suburban HS?

9. Do teacher websites improve student performance in class?

10. Does focus on minor rules (flip-flops and hats) reduce student adherence to major rules (insubordination or class cutting)?

Be curious!

Page 44: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Research Methods1. Description – gathering evidence about A

and B2. Correlation – A and B are related3. Experiment – A causes B

Page 45: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Descriptive Research Methods in Psychology Case Studies

Detailed in-depth description and analysis of one or a few people

Observation, scores on psychological tests, interviews etc.

Prominent in psychologyPiaget used this to develop his theory of

cognitive development Takes advantage of nonreplicable situationsObserver bias is a problemUnable to make generalizations past person

being studied

Page 46: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Research Methods in Psychology Naturalistic Observation

Systematic observation in natural settingThe main drawback is observer bias

○ (expectations or biases of the observer that might distort or influence the interpretation of what was observed.)

Observing and recording behavior of animals in the wild, to recording self-seating patterns in lunch rooms in a multiracial school constitutes naturalistic observation.

Not replicable so you can’t generalize

Page 47: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Research Methods in Psychology Surveys

A technique for ascertaining the self-reported attitudes, opinions or behaviors of people usually by questioning a representative, random sample of people.

Questionnaires or interviews, such as polls prior to an election

Can generate a lot of information for a fairly low cost

Questions must be constructed carefully so as to not elicit socially appropriate answers

Page 48: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Survey

Wording can change the results of a survey.

Q: Should cigarette ads and pornography be allowed on television? (not allowed vs. forbid)

Wording Effect

Page 49: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Survey

A tendency to overestimate the extent to which others share our

beliefs and behaviors.

False Consensus Effect

Page 50: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Survey Random Sampling

From a population if each member has an

equal chance of inclusion into a

sample, we call that a random sample

(unbiased). If the survey sample is

biased, its results are questionable.

The fastest way to know about the marble color ratio is to blindly transfer a few into a smaller jar and count them.

Page 51: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

ComparisonResearch Method Advantages Limitations

NaturalisticObservation

•More accurate than reports after the fact•Behavior is more natural

•Observer can alter behavior•Observational Bias•Cannot be generalized

Case Studies •Depth•Takes advantage of circumstances that could not be coordinated in an experiment

•Not representative•Time consuming and expensive•Observational Bias

Surveys • Immense amount of data•Quick and inexpensive

• Sampling biases can skew results•Bad Questions can corrupt data•Accuracy depends on the ability and willingness of the participants.

Page 52: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Research Methods in Psychology Experimental Research

The only research method that can be used to determine cause and effect

Often called the experimental methodA researcher systematically manipulates a

variable under controlled conditions.

Page 53: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Components of an Experiment Participants or subjects Variable – Factors that can have different values Operational Definition – Describes the specific

procedure used to determine the presence of a variable

Independent variable (IV) Cause (what you are studying) This is the variable that is manipulated by the

experimenter Dependent variable (DV)

Effect (result of experiment) This is the variable that is measured by the experimenter It DEPENDS on the independent variable

Page 54: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Components of an Experiment cont’d

Things to worry aboutConfounding/Intervening Variables – differences (other

than the IV of course) that arise due to poor planning, sloppy work, or bias.

Experimenter Bias - Expectations by the experimenter that might influence the results of an experiment or its interpretation.

Page 55: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Hint

A good way to determine the IV from the DV is to word the Hypothesis in the form of an “If . . . then . . .” statement.

What follows the IF is the IV What follows the THEN is the DV

Page 56: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Experimental group Receives treatment or has the DV changed

Control groupDoes not receive treatment or doesn’t have the DV

changed, but is the same in every other wayDemand Characteristics – clues participants perceive

about the experiment suggesting how they should respond.

Components of an Experiment that involves treatments of some kind.

Page 57: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Clinical Research

Studies performed in humans that are intended to increase knowledge about how well a diagnostic test or treatment

works in a particular patient population.

Page 58: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

In evaluating drug therapies it important to keep the patients and experimenter’s assistants blind to

which patients got real treatment and which placebo.

Clinical Research cont’d

Double-blind Procedure11b

Participants don’t know which treatment group – experimental or

control – they are in

Single-blind Procedure11a

Placebo / Placebo effect12 Fake treatment / Some paricipants

expect improvement in health so they imagine it

Page 59: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Assigning participants to experimental (Breast-fed) and control (formula-fed)

conditions by random assignment minimizes pre-existing differences

between the two groups.

Clinical Research cont’d

Random Assignment

This is not the same as random selection!

Page 60: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Breast milk makes babies smarter!

A summary of steps during experimentation.

Page 61: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Experimentation

Like other sciences, experimentation makes the backbone of research in

psychology. Experiments isolate causes and their effects.

Exploring Cause and Effect

Page 62: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

AP PSYCHOLOGY

Research Methods: Correlation

Page 63: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Hypothesis is a testable prediction that lets us accept, reject or revise a

theory.

For Example: If families do not stress gender differences then there will be

fewer sex differences in siblings.

Hypothesis

Page 64: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Theory is an EXPLANATION based on evidence that PREDICTS behaviors or events.A Theory must:1. Fit the known facts2. Predict new discoveries3. Be falsifiable4. Be simple. The simpler the better – Occam’s RazorFamilies influence the gendering of their

children.

Theory

Page 65: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology
Page 66: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Research Methods in Psychology Correlational Research

Research technique based on the naturally occurring relationship between two or more variables

Used to make PREDICTIONS, such as the relation between SAT scores and success at college

Cannot be used to determine cause and effect

Page 67: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Perfect positivecorrelation (+1.00)

Scatterplot is a graph that comprises of points generated by values of two

variables. The slope of points depicts the direction, The amount of scatter shows the strength

of relationship.

Scatterplots

Page 68: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

No relationship (0.00)Perfect negativecorrelation (-1.00)

Scatterplot on the left shows a relation between the variables, and the one on the right shows no relationship between the two

variables.

Scatterplots

Page 69: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Correlation

When one trait or behavior accompanies another, we say the two

correlate.

Correlation coefficient

Indicates directionof relationship

(positive or negative)

Indicates strengthof relationship(0.00 to 1.00)

r = 0.37+

Correlation Coefficient is a statistical measure of

relationship between two variables.

Page 70: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Operational Definition

An exact description of how to derive a value for a characteristic you are measuring. It includes a precise definition of the characteristic and how, specifically, data collectors are to measure the characteristic.

What you are studying determines the type of data you get.

Page 71: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Study of Low Self Esteem and Depression You do the research because you

assume the two are related Compare two variables

Variable 1 = Score on a self-esteem testVariable 2 = Length of a bought of

depression in months

Page 72: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

–Sco

re o

n a

self-

est

eem

test

– Length of a bought of depression in months

Page 73: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

or

Correlation and Causation

Page 74: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Correlation is not Causation:It only predicts!!!! Children with big feet reason better than

children with small feet. (Children who are older have bigger feet than

younger children; thus they can reason better) Study done in Korea: The most predictive

factor in the use of birth control use was the number of appliances in the home.

(Those who have electrical appliances probably have higher socioeconomic level, and thus are probably better educated.)

Page 75: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Correlation is not Causation:It only predicts!!!! People who often ate Frosted Flakes as

children had half the cancer rate of those who never ate the cereal. Conversely, those who often ate oatmeal as children were four times more likely to develop cancer than those who did not.

Cancer tends to be a disease of later life. Those who ate Frosted Flakes are younger. In fact, the cereal was not around until the 1950s (when older respondents were children, and so they are much more likely to have eaten oatmeal.)

Page 77: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

The Simpsons(Season 7, "Much Apu About

Nothing") Homer: Not a bear in sight. The "Bear Patrol" is working like a charm!

Lisa: That's specious reasoning, Dad.

Homer: [uncomprehendingly] Thanks, honey.

Lisa: By your logic, I could claim that this rock keeps tigers away.

Homer: Hmm. How does it work? Lisa: It doesn't work; it's just a

stupid rock! Homer: Uh-huh. Lisa: But I don't see any tigers

around, do you? Homer: (pause) Lisa, I want to

buy your rock.

Page 78: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Consider the following research undertaken by the University of Texas Health Science Center at San Antonio appearing to show a link between consumption of diet soda and weight gain.

The study of more than 600 normal-weight people found, eight years later, that they were 65 percent more likely to be overweight if they drank one diet soda a day than if they drank none. And if they drank two or more diet sodas a day, they were even more likely to become overweight or obese.

Page 79: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Third or Missing Variable Problem

A relationship other than causal might exist

between the two variables. It's possible that there is some other variable or

factor that is causing the outcome.

Page 80: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

There are two relationships which can be mistaken for causation:

1. Common response2. Confounding

Page 81: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

Ice cream sales and the number of shark attacks on swimmers are correlated.

• Skirt lengths and stock prices are highly correlated (as stock prices go up, skirt lengths get shorter).

• The number of cavities in elementary school children and vocabulary size are strongly correlated.

Page 82: What is Psychology?  Psychology is the scientific study of behavior and mental processes  Scientific? Not just common sense or guesses Psychology

1. Common Response:

Both X and Y respond to changes in some unobserved variable, Z. All three of our previous examples are examples of common response.