lecture 2 psychology and the scientific method

8/2/2019 Lecture 2 Psychology and the Scientific Method

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2006 by The McGraw-Hill Companies, Inc. All rights reserved.

Psychology Questions

We dont always know how people will behave

or what they think. We need to do research.

For example, answer True or False to these

questions:


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Psychology Questions (continued)

Mothers talk to their younger children differentlythan they talk to their older children. True orfalse?

False. Haden (1998) found that mothers use the sameconversation styles (elaborative or repetitive) with theirdifferent-age children.

Haden, C. A. (1998). Reminiscing with different children:Relating maternal stylistic consistency and sibling similarity intalk about the past. Developmental Psychology, 34, 99-114.


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Few students will confess to ruining a computerprogram if they didnt do it. True or false?

False. Kassin and Kiechel (1996) found that 69% of

students in their study falsely confessed to ruining a

computer program and signed a written confession.

Kassin, S. A., & Kiechel, K. L. (1996). The social psychology offalse confessions: Compliance, internalization, andconfabulation. Psychological Science, 7, 125-128.


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Most individuals will notice if a person they aretalking to is replaced by another person. True orfalse?

False. Simons and Levin (1998) found that only 47% ofparticipants in one study and 33% of participants in asecond study noticed that the person changed to a different

person mid-way through their conversation.

Simons, D. J., & Levin, D. T. (1998). Failure to detect changesto people during a real-world interaction. Psychonomic Bulletin

and Review, 5, 644-649.


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7/41 2006 by The McGraw-Hill Companies, Inc. All rights reserved.

The Scientific Method

The scientific method is the way that scientificpsychologists gain knowledge about behaviorand mental processes.

The scientific method is not aparticulartechnique or tool.

Instead, it is ageneralapproach to gainingknowledge.



The scientific method (continued)

We can compare the scientific method to oureveryday, nonscientific ways of gaining

knowledge on several dimensions:

general approach instruments

observation measurement

reporting hypothesesconcepts attitude



General Approach

Nonscientific

Intuitive

judgments anddecisions are based on

what feels right.

Scientific

Empirical

judgments anddecisions are based ondirect observationandexperimentation.



Observation

Nonscientific

Casual,

uncontrolled

personal biases andother factors influence

observation.

Scientific

Systematic,controlled controlis the

essential ingredient ofscience.

Scientists gain thegreatest control whenthey conduct anexperiment.



Observation (continued)

Control: Scientists investigate the effect of variousfactors one at a time in an experiment.

An experiment has at least one independent variable

and at least one dependent variable. Independent Variable (IV): A factor that researchers

control or manipulate in order to determine theeffect on behavior.

A minimum of two levels: The treatment (experimental)condition and the control condition Example: In the Pennebaker and Francis (1996) study, the independent

variable was whether students wrote about adjusting to college(experimental condition) or about superficial topics (control condition).



Observation (continued)

Dependent Variable (DV): The measure of behaviorthat is used to assess the effect of the independent

variable.

Example: In the Pennebaker and Francis (1996) study onthe effects of emotional writing compared to superficial

writing, one dependent variable was students Grade Point

Average (GPA).

In most psychology research, several dependent variablesare measured to assess the effects of the independentvariable.

For example, Pennebaker and Francis also measured students health.



Reporting

Nonscientific

Biased, subjective Personal impressions

are reported.

Scientific

Unbiased, objective observations and

inferences areseparate.

interobserveragreement isimportant.



Concepts

Nonscientific

AmbiguousWe arent clear in the

meaning of the wordswe use.

For example, what dowe mean byintelligence?

Scientific

Clear definitions Define specifically

what we mean by ourconcepts

A constructis aconcept or idea usedin psychological

theories.



Constructs

There are many psychological constructs.

Examples: aggression, depression, emotion, intelligence, memory,

personality, stress, well-being.

An operational definitionis the specificprocedure used to produce and measure a

construct.


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Constructs (continued)

Match each construct with an operational definition:

Construct Operational DefinitionA. score on the Minnesota Multiphasic

Aggression Personality InventoryDepression B. score on the final exam of this course

Intelligence C. number of times person hits another person

Memory D. number of depression symptoms from the

Knowledge of Diagnostic and Statistical Manual

research methods E. score on the Wechsler Adult Intelligence

Personality Scale (WAIS)

F. score on the Digit-Span Test of memory


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Measurements

Nonscientific

Not valid or reliable

measures of ourconcepts that areinaccurate orinconsistent.

Scientific

Valid and reliable

validmeasures get atthe truth,

reliablemeasures areconsistent.



Measurements (continued)

Physical measurementinvolves dimensions thathave agreed-upon standards and instruments.Examples: length, weight, time

Psychological measurementis used to measureconstructs for which there is no agreed uponstandard or instrument.Are there agreed upon standards for what is

considered beauty, intelligence, or aggression? Psychologists develop measures to assess these

and other psychological constructs.


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Measurements (continued)

Measures must be validand reliable. Validityrefers to truthfulness; a valid measure is

one that measures what it claims to measure.Example: Do exams in your courses test the material

covered in course lectures and texts? Reliabilityrefers to the consistency of a measure.

For example, a measure is considered reliable whendifferent observers consistently agree about an

observation. Note that a measure may be reliable but not valid.

For example, a scale that consistently underreportssomeones weight is reliable but not valid.


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Hypotheses

Nonscientific

Untestable concepts not defined

clearly,

circular,

appeals to ideas outsiderealm of science.

Scientific

Testable concepts are clearly

defined and can bemeasured.


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Hypotheses (continued)

Hypotheses are nottestable if they have any of thesethree characteristics:

Constructs are not adequately defined.

Example: People become aggressive following exposure to mediaviolence because the violence is disturbing.

The hypothesis is circularthe event itself is used as anexplanation of the event.

Example: People become aggressive following exposure to media

violence because theybecome verbally or physically abusive.

The hypothesis appeals to ideas or forces that are notrecognized by science.

Example: People become aggressive following exposure to media

violence because they are overcome bythe Devil.


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Attitude

Nonscientific

Uncritical,accepting

accept claims with

insufficient evidence,ignore contradictoryevidence

Scientific

Critical, skeptical behavior and mental

processes arecomplex,

human mistakes aremade (even inscience).


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Goals of the Scientific Method

Researchers use the scientific method to meetfour research goals:

description

prediction

explanation application


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Description

Researchers define, classify, catalogue, orcategorize events and their relationships to

describe mental processes and behavior.

Example:Psychologists describe symptoms ofdepression. One operational definition of depression

comes from the list of symptoms in the Diagnostic andStatistical Manual.


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Description (continued)

Most psychology research is nomotheticrather thanidiographic.

Nomothetic: large sample sizes, average performance of agroup

Idiographic: individual case studies

Nomothetic researchers appreciate there are importantdifferences among individuals; they seek, however, toemphasize similaritiesamong individuals.

Most psychology research is quantitativerather thanqualitative.

Quantitative: statistical summaries of performance

Qualitative: verbal summaries of research findings


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Prediction

When researchers identify correlations(relationships) among variables, they are able topredict mental processes and behavior.

Example:As level of depression increases, individualsexhibit more helplessness (failure to initiate activities

and pessimism regarding the future).


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Prediction (continued)

A variableis a dimension on which people differ,or vary.

Examples:childhood loss of parent (yes/no),symptoms of depression, aggressiveness, age,emotional problems, stressful life events, physical

illness


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A correlationoccurs when two measures of

the same people, events, or things vary

together or go together.

Example:The more stressful life events a person

experiences (one variable), the more likely they are toexperience physical illness (a second variable).


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When two variables are correlated, if we knowpeoples scores for one variable, we canstatistically compute (predict) their scores for

the second variable. For example, if we know the extent to which someone has

experienced life stress, we can compute their likelihood ofexperiencing physical illness (and predict stress based onillness).

Because test scores (SAT, GRE) are correlated with grades,we can predict students grades based on knowing their testscores (and predict test scores from grades).


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Correlation does not imply causation.We dont knowwhythevariables are correlated.

For example, theres a correlation between the amount

of hair in ones ear and the presence of heart disease.(true) Does this mean that having hair in ones ears causesheart

disease?

Does this mean that having heart disease causeshair to growin the ears?

Or is there some other variable that accounts for therelationship between ear hair and heart disease?


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Explanation

Researchers understand and can explain aphenomenon when they can identify its cause(s).

Example:Research participants exposed tounsolvable problems become more pessimistic andless willing to do new tasks (i.e., they becomehelpless) than participants who are asked to do

solvable problems.


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Explanation (continued)

Researchers conduct controlled experimentsto identifythe causes of a phenomenon.

Control requires that researchers manipulatefactors, one

at a time, to determine their effect on the event ofinterestthese are independent variables.

Researchers observe the effect of the independentvariable by measuringdependent variables.

Remember: The word experiment is often used in

everyday language to mean the same thing asresearch, but the word experimentrefers to a very

specific type of research study.


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Using experiments, researchers can make causal inferencesstatements about the cause of an event or behavior.

Three conditions for making a causal inference:

1. Covariation of events: If one event causes the other, the twoevents must vary together (when one changes, the other mustchange also).

2. Time-order relationship: The presumed cause must occurbefore the presumed effect.

3. Elimination of plausible alternative causes: We accept a causalexplanation only when other possible causes of the effecthave been ruled out.


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Example of a causal inference based on researchfindings:

Exposure to media violence causesan increase in thelikelihood of aggressive and violent thoughts, emotions, andbehaviors immediately after the exposure.

Based on this research, we know Exposure to media violence and aggression vary together.

Aggression follows afterthe exposure (not before).

Other explanation for the relationship between exposure tomedia violence and aggression have been ruled out.


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Causal Inferences Scientific control requires that the effects of independent

variables are isolated.

A confoundingoccurs when two potentially effectiveindependent variables are allowed to vary togethersimultaneouslywe cannot determine which variablecaused the effect on the dependent variable.

When an experiment is free of confoundings, we can make acausal inference regarding the effect of the independentvariable on the dependent variable.


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Describe the confounding in this research example:A psychologist seeks to demonstrate the effectiveness of a new

therapy for helping students to cope with stress. One group ofstudents receives the new treatment during the fall term; a

second group of students is placed on a waiting list to receive thetreatment during the next term (control group). To make surethe students in the control group maintain their interest in theresearch project, an assistant calls them every week to check inand see how theyre doing. The psychologist measures the

coping of students in both the treatment and control groups atthe end of the fall term and discovers no difference in the copingfor the two groups and both are coping well. The researcherdecides to abandon the new therapy.


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Generalization

Researchers are not interested just in the one sample ofpeople or the one set of circumstances they tested.

They wish togeneralizea studys findings to differentpopulations, settings, and conditions beyond those usedin the specific study.

Can we generalize or apply the findings from psychologystudies with college students samples to other people?

Can we generalize the findings of highly controlled laboratorystudies to real-world settings?

For example, can a study that examines conditions ofaggression in the lab with college students be used tounderstand real-life conditions of aggression?


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Application

Psychologists apply their knowledge andresearch methods to improve peoples lives.

Example:Treatment that encourages depressedindividuals to attempt tasks that can be mastered oreasily attained decreases depressives helplessness

and pessimism.


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lecture 2 psychology and the scientific method

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