Psychology Psychology Research Methods: Experiments All rights reserved by

Research Questions Does playing violent videogames produce aggression in children? Does playing violent videogames produce aggression in children? What are the long-term effects of early malnutrition? What are the long-term effects of early malnutrition? How do children of different ages react to a divorce of their parents? How do children of different ages react to a divorce of their parents? All rights reserved by

Origins of Assumptions and Beliefs? Word-of-Mouth Folklore Word-of-Mouth Folklore –Friends and relatives –Portrayals of children/families on TV/books –Religious teachings –Talk shows Personal Experiences Personal Experiences Expert Opinions Expert Opinions Research Evidence Research Evidence All rights reserved by

Research evidence is valuable because results are: Observations of many children Observations of many children Unbiased observers Unbiased observers Reliable, valid methods of measurement Reliable, valid methods of measurement Careful control Careful control All rights reserved by

Theories An orderly, integrated set of statements that describes, explains, and predicts behavior An orderly, integrated set of statements that describes, explains, and predicts behavior Vital tools Vital tools –Guide and give meaning –Practical action All rights reserved by

Theories  hypotheses Theories  hypotheses –Predictions about behavior Research Question vs. Hypothesis Research Question vs. Hypothesis Need plan (research design) for conducting specific activities (research method) Need plan (research design) for conducting specific activities (research method) All rights reserved by

Examine whether a relationship exists between variables Examine whether a relationship exists between variables Independent Variable Independent Variable Dependent Variable Dependent Variable –Does eating candy produce hyperactivity? –Does playing violent videogames produce aggression in children? –Does drinking wine lower your risk for heart disease? –Does exposure to smoke increase the risk of SIDS? All rights reserved by

Statistical Significance Statistical Significance Reliability – consistency Reliability – consistency Validity Validity –External/ecological validity –Internal validity All rights reserved by

Correlational Research The Correlational Design The Correlational Design –2 or more variables meaningfully related –Correlation coefficient (r) to to Sign indicates direction Sign indicates direction – Positive (+) – Negative (-) All rights reserved by

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. All rights reserved by

Correlational Research Correlational studies ≠ causation. Correlational studies ≠ causation. –Causal direction unknown –Could be due to a third, unmeasured (confounding) variable All rights reserved by

Experimental Design Cause/effect Cause/effect Systematically manipulate a variable Systematically manipulate a variable Random assignment Random assignment –Control group –Experimental/treatment group(s) Hold conditions constant Hold conditions constant –Eliminate threat of confounding variables All rights reserved by

Field Experiment Natural setting Natural setting Example in text: Belgian delinquents living in minimum-security institution for adolescent boys Example in text: Belgian delinquents living in minimum-security institution for adolescent boys All rights reserved by

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., All rights reserved by 14

Field Experiment May not be aware that they are participating May not be aware that they are participating All rights reserved by

Study the effects of malnutrition or sensory deprivation on infant motor development. Study the effects of malnutrition or sensory deprivation on infant motor development. Volunteers? Volunteers? All rights reserved by

Natural/Quasi-Experiment Naturally occurring events Naturally occurring events No manipulation of variables No manipulation of variables No random assignment No random assignment All rights reserved by

Strengths and Limitations of General Research Designs All rights reserved by 18

Self-Report Methodologies Interviews/Questionnaires Interviews/Questionnaires –Unstructured to structured –Difficult with children Clinical Method Clinical Method –Can ask follow-up questions specific to individual being interviewed (thus, less structured) All rights reserved by

Self-Report Methodologies Limitations Limitations –Honesty/accuracy –Interpretation of questions –Use with children Strengths Strengths –Efficient (large amounts of data, short amount of time) –Confidentiality improves accuracy All rights reserved by

Observational Methodologies Naturalistic Observation Naturalistic Observation –Observations in common, everyday (i.e., natural) settings –Strengths: easy, behavior is natural Thus _________ validity is high… Thus _________ validity is high… –Limitations: frequency of behavior; reactivity All rights reserved by

Observational Methodologies Structured Observations Structured Observations –Laboratory setting –Set up a scenario –Strengths: same environment, attempt to elicit low frequency behaviors –Limitations: external validity? All rights reserved by

Case Study a detailed portrait of a single individual; can also describe groups a detailed portrait of a single individual; can also describe groups –Strength – depth –Limitations Difficult to compare Difficult to compare Generalizability Generalizability Observer bias Observer bias All rights reserved by

Ethnography Collect data by living within the cultural community for an extended period Collect data by living within the cultural community for an extended period –Strengths: understanding cultural conflicts and impacts on development –Limitations: subjective, may not be generalizable All rights reserved by

Psychophysiological Methods Examine relationship between physiological responses and behavior Examine relationship between physiological responses and behavior –Heart Rate – compared to baseline, decrease may indicate interest –EEG – brain wave activity, showing arousal states; stimulus detection Strengths Strengths –Can examine behaviors in infants/young children before they can self-report All rights reserved by

Psychophysiological Methods Limitations? Limitations? –High degree of inference –Change in physiology due to stimuli? All rights reserved by

Table 1.3 Strengths and Limitations of Seven Common Research Methods All rights reserved by 27

Designs for Studying Development Longitudinal Design Longitudinal Design –Same participants over time Can assess stability Can assess stability Can identify trends Can identify trends Can help understand individual differences Can help understand individual differences All rights reserved by

Designs for Studying Development Longitudinal Design (con’t) Longitudinal Design (con’t) –Limitations Costly and time-consuming Costly and time-consuming Selective attrition Selective attrition Practice effects Practice effects Cohort effects Cohort effects All rights reserved by

Designs for Studying Development Cross-sectional Design Cross-sectional Design –Groups of people of differing ages (although sometimes the same age…) studied at one point in time –Strengths? Efficient (time & money), no practice effects or attrition Efficient (time & money), no practice effects or attrition –Limitations? Information on individual change is not available Information on individual change is not available Confound age and cohort effects Confound age and cohort effects All rights reserved by

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. All rights reserved by 31

Designs for Studying Development Microgenetic Design Microgenetic Design –Illuminate processes that promote developmental change Repeatedly expose children ready for a developmental change to experiences thought to produce that change Repeatedly expose children ready for a developmental change to experiences thought to produce that change Monitor behavior as it changes Monitor behavior as it changes All rights reserved by

Designs for Studying Development Microgenetic Design (con’t) Microgenetic Design (con’t) –Strengths Able to see the process of change Able to see the process of change –Limitations Time consuming Time consuming Repeated observations Repeated observations All rights reserved by

Table Strengths and Limitations of Four Developmental Designs All rights reserved by 34

Components of an Experiment Participants 1 or subjects Variable 2 – Factors that can have different values Operational Definition 3 – 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 All rights reserved by 35

A researcher is interested in whether there is a relationship between the sporting events in which siblings choose to engage. This researcher sent a survey to 500 different families and asked parents to write down the age of each child and to list in which sports each child participated. The researcher collected all of the surveys and examined whether there was a relationship between siblings’ choice of sports. A researcher is interested in whether there is a relationship between the sporting events in which siblings choose to engage. This researcher sent a survey to 500 different families and asked parents to write down the age of each child and to list in which sports each child participated. The researcher collected all of the surveys and examined whether there was a relationship between siblings’ choice of sports. –Correlational or Experimental? –Method? Observation, interview/questionnaire, clinical method, case study, ethnography, psychophysiological Observation, interview/questionnaire, clinical method, case study, ethnography, psychophysiological –Cross-sectional, longitudinal, or sequential? –IV and DV? All rights reserved by

A researcher is interested in whether drinking water right before bed increases the likelihood that children will wet the bed at night. The researcher recruits 50 5-year-old children to participate in her study. Twenty-five children are given two glasses of water two hours before their bedtime (one glass per hour) and twenty-five children are prohibited from receiving liquids within two hours of their bedtime. The researcher collects information from the parents of the children participating for one week – parents are telephoned and asked to report whether the child wet the bed each night. A researcher is interested in whether drinking water right before bed increases the likelihood that children will wet the bed at night. The researcher recruits 50 5-year-old children to participate in her study. Twenty-five children are given two glasses of water two hours before their bedtime (one glass per hour) and twenty-five children are prohibited from receiving liquids within two hours of their bedtime. The researcher collects information from the parents of the children participating for one week – parents are telephoned and asked to report whether the child wet the bed each night. –Correlational or Experimental? –Method? Observation, interview/questionnaire, clinical method, case study, ethnography, psychophysiological Observation, interview/questionnaire, clinical method, case study, ethnography, psychophysiological –Cross-sectional, longitudinal, or sequential? –IV and DV? All rights reserved by

A researcher was interested in how children learn how to settle disagreements with peers. The researcher talked to his 5-year-old daughter and asked her to describe how she interacted with her peers. The researcher then read a few stories to his daughter about children her age who got into disagreements and asked her what she would do in that situation. The researcher continued to interview his daughter like this for five years. A researcher was interested in how children learn how to settle disagreements with peers. The researcher talked to his 5-year-old daughter and asked her to describe how she interacted with her peers. The researcher then read a few stories to his daughter about children her age who got into disagreements and asked her what she would do in that situation. The researcher continued to interview his daughter like this for five years. –Correlational or Experimental? –Method? Observation, interview/questionnaire, clinical method, case study, ethnography, psychophysiological Observation, interview/questionnaire, clinical method, case study, ethnography, psychophysiological –Cross-sectional, longitudinal, or sequential? –IV and DV? All rights reserved by

A researcher was interested in whether the construct of helplessness (e.g., low persistence, negative affect, negative self-evaluations) is similar in toddlers, preschoolers, and older children. The researcher recruited a group of 2-year-olds and a group of 4-year-olds and brought them into a playroom setting. The children were videotaped playing with impossible puzzles and “helpless” behaviors were measured. The children were brought back two years later (the first group of children was then 4 and the second group was 6) and were given another set of impossible puzzles. Helpless behaviors were again measured. A researcher was interested in whether the construct of helplessness (e.g., low persistence, negative affect, negative self-evaluations) is similar in toddlers, preschoolers, and older children. The researcher recruited a group of 2-year-olds and a group of 4-year-olds and brought them into a playroom setting. The children were videotaped playing with impossible puzzles and “helpless” behaviors were measured. The children were brought back two years later (the first group of children was then 4 and the second group was 6) and were given another set of impossible puzzles. Helpless behaviors were again measured. –Correlational or Experimental? –Method? Observation, interview/questionnaire, clinical method, case study, ethnography, psychophysiological Observation, interview/questionnaire, clinical method, case study, ethnography, psychophysiological –Cross-sectional, longitudinal, or sequential? –IV and DV? All rights reserved by

A researcher is interested in whether boys or girls are more aggressive when playing with peers. The researcher goes to a playground every day for 5 weeks and watches children playing with one another. The researcher records every instance of aggression that he witnesses. A researcher is interested in whether boys or girls are more aggressive when playing with peers. The researcher goes to a playground every day for 5 weeks and watches children playing with one another. The researcher records every instance of aggression that he witnesses. –Correlational or Experimental? –Method? Observation, interview/questionnaire, clinical method, case study, ethnography, psychophysiological Observation, interview/questionnaire, clinical method, case study, ethnography, psychophysiological –Cross-sectional, longitudinal, or sequential? –IV and DV? All rights reserved by

A researcher is interested in whether a mother’s diet during pregnancy influences her baby’s cognitive ability. The researcher finds a group of women who were malnourished during pregnancy and tests their infants’ cognitive skills and finds another group of women who were not malnourished during pregnancy and gives the same test to their infants. The researcher then gives all of the children an IQ test when they reach the age of 6. A researcher is interested in whether a mother’s diet during pregnancy influences her baby’s cognitive ability. The researcher finds a group of women who were malnourished during pregnancy and tests their infants’ cognitive skills and finds another group of women who were not malnourished during pregnancy and gives the same test to their infants. The researcher then gives all of the children an IQ test when they reach the age of 6. –Correlational or Experimental? –Method? Observation, interview/questionnaire, clinical method, case study, ethnography, psychophysiological Observation, interview/questionnaire, clinical method, case study, ethnography, psychophysiological –Cross-sectional, longitudinal, or sequential? –IV and DV? All rights reserved by

Ethical Considerations Research Ethics – standards of conduct to protect participants from harm Research Ethics – standards of conduct to protect participants from harm –Protection from harm –Benefits to risks ratio –Informed consent –Confidentiality –Deception/Debriefing/Knowledge of Results All rights reserved by