Psychology Psychology Research Methods: Experiments All rights reserved by .

PsychologyPsychology

Research Methods: ExperimentsResearch Methods: Experiments

All rights reserved by All rights reserved by www.gyanbigyan.comwww.gyanbigyan.com 11

Research QuestionsResearch Questions

• Does playing violent videogames Does playing violent videogames produce aggression in children?produce aggression in children?

• What are the long-term effects of What are the long-term effects of early malnutrition?early malnutrition?

• How do children of different ages How do children of different ages react to a divorce of their parents?react to a divorce of their parents?


Origins of Assumptions and Origins of Assumptions and Beliefs?Beliefs?• Word-of-Mouth FolkloreWord-of-Mouth Folklore

– Friends and relativesFriends and relatives– Portrayals of children/families on Portrayals of children/families on

TV/booksTV/books– Religious teachingsReligious teachings– Talk showsTalk shows

• Personal ExperiencesPersonal Experiences

• Expert OpinionsExpert Opinions

• Research EvidenceResearch EvidenceAll rights reserved by All rights reserved by www.gyanbigyan.comwww.gyanbigyan.com 33

Research evidence is valuable Research evidence is valuable because results are:because results are:

• Observations of many childrenObservations of many children

• Unbiased observersUnbiased observers

• Reliable, valid methods of Reliable, valid methods of measurementmeasurement

• Careful controlCareful control


TheoriesTheories

• An orderly, integrated set of An orderly, integrated set of statements that statements that describesdescribes, , explainsexplains, , and and predicts predicts behaviorbehavior

• Vital toolsVital tools– Guide and give meaningGuide and give meaning– Practical actionPractical action


• Theories Theories hypotheses hypotheses– Predictions about behaviorPredictions about behavior

• Research Question vs. HypothesisResearch Question vs. Hypothesis

• Need plan (research design) for Need plan (research design) for conducting specific activities conducting specific activities (research method)(research method)


• Examine whether a relationship Examine whether a relationship exists between variablesexists between variables

• Independent VariableIndependent Variable

• Dependent VariableDependent Variable– Does eating candy produce Does eating candy produce

hyperactivity?hyperactivity?– Does playing violent videogames Does playing violent videogames

produce aggression in children?produce aggression in children?– Does drinking wine lower your risk for Does drinking wine lower your risk for

heart disease?heart disease?– Does exposure to smoke increase the Does exposure to smoke increase the

risk of SIDS?risk of SIDS? All rights reserved by All rights reserved by www.gyanbigyan.comwww.gyanbigyan.com 77

• Statistical SignificanceStatistical Significance

• Reliability – consistencyReliability – consistency

• ValidityValidity– External/ecological validityExternal/ecological validity– Internal validityInternal validity


Correlational ResearchCorrelational Research• The Correlational DesignThe Correlational Design

– 2 or more variables meaningfully related2 or more variables meaningfully related– Correlation coefficient (r)Correlation coefficient (r)

•+1.00 to -1.00+1.00 to -1.00

•Sign indicates direction Sign indicates direction – Positive (+) Positive (+) – Negative (-)Negative (-)


•Figure 1.2 Plot of a hypothetical positive correlation between the amount of violence that children see on television and the number of aggressive responses they display. Each dot represents a specific child who views a particular level of televised violence (shown on the horizontal axis) and commits a particular number of aggressive acts (shown on the vertical axis). Although the correlation is less than perfect, we see that the more acts of violence a child watches on TV, the more inclined he or she is to behave aggressively toward peers.


Correlational ResearchCorrelational Research

•Correlational studies Correlational studies ≠ ≠ causation.causation.– Causal direction unknownCausal direction unknown– Could be due to a third, Could be due to a third,

unmeasured (unmeasured (confoundingconfounding) ) variablevariable


Experimental DesignExperimental Design

• Cause/effectCause/effect

• Systematically manipulate a variableSystematically manipulate a variable

• Random assignmentRandom assignment– Control groupControl group– Experimental/treatment group(s)Experimental/treatment group(s)

• Hold conditions constantHold conditions constant– Eliminate threat of confounding Eliminate threat of confounding

variablesvariables


Field ExperimentField Experiment

• Natural settingNatural setting

• Example in text: Belgian delinquents Example in text: Belgian delinquents living in minimum-security institution living in minimum-security institution for adolescent boysfor adolescent boys


•Figure 1.3 Mean physical aggression scores in the evening for highly aggressive (HA) and less aggressive (LA) boys under baseline conditions and after watching violent or neutral movies. ADAPTED FROM LEVENS ET AL., 1975.

All rights reserved by www.gyanbigyan.com

14

Field ExperimentField Experiment

• May not be aware that they are May not be aware that they are participatingparticipating


• Study the effects of malnutrition or Study the effects of malnutrition or sensory deprivation on infant motor sensory deprivation on infant motor development.development.

• Volunteers?Volunteers?


Natural/Quasi-ExperimentNatural/Quasi-Experiment

• Naturally occurring eventsNaturally occurring events

• No manipulation of variablesNo manipulation of variables

• No random assignmentNo random assignment


Strengths and Limitations of General Research Designs


18

Self-Report MethodologiesSelf-Report Methodologies

• Interviews/QuestionnairesInterviews/Questionnaires– Unstructured to structuredUnstructured to structured– Difficult with childrenDifficult with children

• Clinical MethodClinical Method– Can ask follow-up questions specific to Can ask follow-up questions specific to

individual being interviewed (thus, less individual being interviewed (thus, less structured)structured)


Self-Report MethodologiesSelf-Report Methodologies

• LimitationsLimitations– Honesty/accuracyHonesty/accuracy– Interpretation of questionsInterpretation of questions– Use with childrenUse with children

• StrengthsStrengths– Efficient (large amounts of data, short Efficient (large amounts of data, short

amount of time)amount of time)– Confidentiality improves accuracyConfidentiality improves accuracy


Observational Observational MethodologiesMethodologies

• Naturalistic ObservationNaturalistic Observation– Observations in common, everyday (i.e., Observations in common, everyday (i.e.,

natural) settingsnatural) settings– Strengths: easy, behavior is naturalStrengths: easy, behavior is natural

•Thus _________ validity is high…Thus _________ validity is high…

– Limitations: frequency of behavior; Limitations: frequency of behavior; reactivityreactivity


Observational Observational MethodologiesMethodologies

• Structured ObservationsStructured Observations– Laboratory settingLaboratory setting– Set up a scenarioSet up a scenario– Strengths: same environment, attempt Strengths: same environment, attempt

to elicit low frequency behaviorsto elicit low frequency behaviors– Limitations: external validity?Limitations: external validity?


Case StudyCase Study

•a detailed portrait of a single a detailed portrait of a single individual; can also describe groupsindividual; can also describe groups– Strength – depthStrength – depth– LimitationsLimitations

•Difficult to compareDifficult to compare

•GeneralizabilityGeneralizability

•Observer biasObserver bias


EthnographyEthnography

• Collect data by living within the Collect data by living within the cultural community for an extended cultural community for an extended periodperiod– Strengths: understanding cultural Strengths: understanding cultural

conflicts and impacts on developmentconflicts and impacts on development– Limitations: subjective, may not be Limitations: subjective, may not be

generalizablegeneralizable


Psychophysiological Psychophysiological MethodsMethods

• Examine relationship between Examine relationship between physiological responses and behaviorphysiological responses and behavior– Heart Rate – compared to baseline, Heart Rate – compared to baseline,

decrease may indicate interestdecrease may indicate interest– EEG – brain wave activity, showing EEG – brain wave activity, showing

arousal states; stimulus detectionarousal states; stimulus detection

• StrengthsStrengths– Can examine behaviors in infants/young Can examine behaviors in infants/young

children before they can self-reportchildren before they can self-report


Psychophysiological Psychophysiological MethodsMethods

• Limitations?Limitations?– High degree of inferenceHigh degree of inference– Change in physiology due to stimuli?Change in physiology due to stimuli?


•Table 1.3 Strengths and Limitations of Seven Common Research MethodsAll rights reserved by www.gyanbigyan.com

27

Designs for Studying Designs for Studying DevelopmentDevelopment

•Longitudinal DesignLongitudinal Design– Same participants over timeSame participants over time

•Can assess stabilityCan assess stability

•Can identify trendsCan identify trends

•Can help understand individual Can help understand individual differencesdifferences



•Longitudinal Design (con’t)Longitudinal Design (con’t)– LimitationsLimitations

•Costly and time-consumingCostly and time-consuming

•Selective attritionSelective attrition

•Practice effects Practice effects

•Cohort effectsCohort effects



• Cross-sectional DesignCross-sectional Design– Groups of people of differing ages Groups of people of differing ages

(although sometimes the same age…) (although sometimes the same age…) studied at one point in timestudied at one point in time

– Strengths?Strengths?•Efficient (time & money), no practice effects Efficient (time & money), no practice effects

or attritionor attrition

– Limitations?Limitations?• Information on individual change is not Information on individual change is not

availableavailable•Confound age and cohort effectsConfound age and cohort effects


Example of a sequential design. Two samples of children, one born in 1998, and one born in 2000 are observed longitudinally between the ages of 6 and 12. The design permits the investigator to assess cohort effects by comparing children of the same age who were born in different years. In the absence of cohort effects, the longitudinal and cross-sectional comparisons in this design also permit the researcher to make strong statements about the strength and the direction of any developmental changes.


31


• Microgenetic DesignMicrogenetic Design– Illuminate processes that promote Illuminate processes that promote

developmental changedevelopmental change•Repeatedly expose children ready for a Repeatedly expose children ready for a

developmental change to experiences developmental change to experiences thought to produce that changethought to produce that change

•Monitor behavior as it changesMonitor behavior as it changes



• Microgenetic Design (con’t)Microgenetic Design (con’t)– StrengthsStrengths

•Able to see the process of changeAble to see the process of change

– LimitationsLimitations•Time consumingTime consuming

•Repeated observationsRepeated observations


Table Strengths and Limitations of Four Developmental DesignsAll rights reserved by www.gyanbigyan.com

34

Components of an Experiment

• Participants1 or subjects• Variable2 – Factors that can have different values• Operational Definition3 – Describes the specific

procedure used to determine the presence of a variable• Independent variable (IV)4

– Cause (what you are studying)– This is the variable that is manipulated by the experimenter

• Dependent variable (DV)5

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


35

• A researcher is interested in whether there is a A researcher is interested in whether there is a relationship between the sporting events in which relationship between the sporting events in which siblings choose to engage. This researcher sent a siblings choose to engage. This researcher sent a survey to 500 different families and asked parents survey to 500 different families and asked parents to write down the age of each child and to list in to write down the age of each child and to list in which sports each child participated. The which sports each child participated. The researcher collected all of the surveys and researcher collected all of the surveys and examined whether there was a relationship between examined whether there was a relationship between siblings’ choice of sports.siblings’ choice of sports.– Correlational or Experimental?Correlational or Experimental?– Method?Method?

•Observation, interview/questionnaire, clinical Observation, interview/questionnaire, clinical method, case study, ethnography, method, case study, ethnography, psychophysiologicalpsychophysiological

– Cross-sectional, longitudinal, or sequential?Cross-sectional, longitudinal, or sequential?– IV and DV?IV and DV? All rights reserved by All rights reserved by

www.gyanbigyan.comwww.gyanbigyan.com 3636

• A researcher is interested in whether drinking water right A researcher is interested in whether drinking water right before bed increases the likelihood that children will wet before bed increases the likelihood that children will wet the bed at night. The researcher recruits 50 5-year-old the bed at night. The researcher recruits 50 5-year-old children to participate in her study. Twenty-five children children to participate in her study. Twenty-five children are given two glasses of water two hours before their are given two glasses of water two hours before their bedtime (one glass per hour) and twenty-five children are bedtime (one glass per hour) and twenty-five children are prohibited from receiving liquids within two hours of their prohibited from receiving liquids within two hours of their bedtime. The researcher collects information from the bedtime. The researcher collects information from the parents of the children participating for one week – parents parents of the children participating for one week – parents are telephoned and asked to report whether the child wet are telephoned and asked to report whether the child wet the bed each night.the bed each night.– Correlational or Experimental?Correlational or Experimental?– Method?Method?

• Observation, interview/questionnaire, clinical Observation, interview/questionnaire, clinical method, case study, ethnography, method, case study, ethnography, psychophysiologicalpsychophysiological

– Cross-sectional, longitudinal, or sequential?Cross-sectional, longitudinal, or sequential?– IV and DV?IV and DV?


• A researcher was interested in how A researcher was interested in how children learn how to settle disagreements children learn how to settle disagreements with peers. The researcher talked to his 5-with peers. The researcher talked to his 5-year-old daughter and asked her to year-old daughter and asked her to describe how she interacted with her describe how she interacted with her peers. The researcher then read a few peers. The researcher then read a few stories to his daughter about children her stories to his daughter about children her age who got into disagreements and asked age who got into disagreements and asked her what she would do in that situation. her what she would do in that situation. The researcher continued to interview his The researcher continued to interview his daughter like this for five years.daughter like this for five years.– Correlational or Experimental?Correlational or Experimental?– Method?Method?

• Observation, interview/questionnaire, clinical method, Observation, interview/questionnaire, clinical method, case study, ethnography, psychophysiologicalcase study, ethnography, psychophysiological

– Cross-sectional, longitudinal, or sequential?Cross-sectional, longitudinal, or sequential?– IV and DV?IV and DV? All rights reserved by All rights reserved by

www.gyanbigyan.comwww.gyanbigyan.com 3838

• A researcher was interested in whether the A researcher was interested in whether the construct of helplessness (e.g., low persistence, construct of helplessness (e.g., low persistence, negative affect, negative self-evaluations) is similar negative affect, negative self-evaluations) is similar in toddlers, preschoolers, and older children. The in toddlers, preschoolers, and older children. The researcher recruited a group of 2-year-olds and a researcher recruited a group of 2-year-olds and a group of 4-year-olds and brought them into a group of 4-year-olds and brought them into a playroom setting. The children were videotaped playroom setting. The children were videotaped playing with impossible puzzles and “helpless” playing with impossible puzzles and “helpless” behaviors were measured. The children were behaviors were measured. The children were brought back two years later (the first group of brought back two years later (the first group of children was then 4 and the second group was 6) children was then 4 and the second group was 6) and were given another set of impossible puzzles. and were given another set of impossible puzzles. Helpless behaviors were again measured.Helpless behaviors were again measured.– Correlational or Experimental?Correlational or Experimental?– Method?Method?

• Observation, interview/questionnaire, clinical method, Observation, interview/questionnaire, clinical method, case study, ethnography, psychophysiologicalcase study, ethnography, psychophysiological



• A researcher is interested in whether boys A researcher is interested in whether boys or girls are more aggressive when playing or girls are more aggressive when playing with peers. The researcher goes to a with peers. The researcher goes to a playground every day for 5 weeks and playground every day for 5 weeks and watches children playing with one another. watches children playing with one another. The researcher records every instance of The researcher records every instance of aggression that he witnesses.aggression that he witnesses.– Correlational or Experimental?Correlational or Experimental?– Method?Method?




• A researcher is interested in whether a mother’s diet A researcher is interested in whether a mother’s diet during pregnancy influences her baby’s cognitive during pregnancy influences her baby’s cognitive ability. The researcher finds a group of women who ability. The researcher finds a group of women who were malnourished during pregnancy and tests their were malnourished during pregnancy and tests their infants’ cognitive skills and finds another group of infants’ cognitive skills and finds another group of women who were not malnourished during women who were not malnourished during pregnancy and gives the same test to their infants. pregnancy and gives the same test to their infants. The researcher then gives all of the children an IQ The researcher then gives all of the children an IQ test when they reach the age of 6.test when they reach the age of 6.– Correlational or Experimental?Correlational or Experimental?– Method?Method?




Ethical ConsiderationsEthical Considerations

• Research Ethics – standards of conduct Research Ethics – standards of conduct to protect participants from harmto protect participants from harm– Protection from harmProtection from harm– Benefits to risks ratioBenefits to risks ratio– Informed consentInformed consent– ConfidentialityConfidentiality– Deception/Debriefing/Knowledge of ResultsDeception/Debriefing/Knowledge of Results


Psychology Psychology Research Methods: Experiments All rights reserved by .

Documents

experimentsall rights

acts of violence

psychology research

specific child

violent videogames

children of different

direction positive negative

number of aggressive