AS Psychology Research Methods Experiments and SelfReports Experiments

AS Psychology Research Methods Experiments and Self-Reports

Experiments Define the term experiment. An experiment looks for a relationship in which an independent variable (IV) is manipulated and is expected to be responsible for changes in the dependent variable (DV).

IVs and DVs Independent Variable (IV): An independent variable is the variable which is manipulated by the experimenter that is presumed to effect the DV. Dependent Variable (DV): The dependent variable is assumed to be effected by the IV. Changes in the DV are presumed to have been caused by the IV.

Extraneous and Confounding Variables Extraneous Variable(s): An extraneous variable is a variable which acts randomly, affecting the DV in all levels of the IV. The three types are experimenter, experimenter situational, situational and participant Confounding Variable: A confounding variable systematically affects one level of the IV. It can obscure the effect of the DV, making the results hard to interpret.

IVs and DVs Self-Check The next 6 slides have a quick description of a study. First 3: Try to identify the independent variables. Second 3: Try to identify the dependent variables.

What is the independent variable? A researcher wants to determine if the color of an office has any effect on worker productivity. In an experiment, one group performs a task in a yellow room while another performs the same task in a blue room. In this example, the colour of the office is the independent variable.

What is the independent variable? Researchers want to learn whether listening to fast-paced music helps students perform better at memorization of facts. In an experiment, one group of students listens to fast-paced music while another group listens to slowpaced music. In this example, the type of music the students listen to is the independent variable.

What is the independent variable? Educators are interested in whether participating in afterschool mathematics tutoring can increase scores on standardized maths exams. In an experiment, one group of students attends an after-school tutoring session twice a week while another group of students does not receive this additional assistance. In this case, participation in an after-school maths tutoring is the independent variable.

What is the dependent variable? Researchers want to discover if listening to classical music helps students earn better grades on a mathematics exam. In this example, the scores on the mathematics exams are the dependent variable.

What is the dependent variable? Researchers are interested in seeing how long it takes people to respond to different sounds. In this example, the length of time it takes participants to respond to a sound is the dependent variable.

What is the dependent variable? Researchers are interested in looking at how alcohol use influences reaction times while driving. The amount of alcohol a participant drinks is the independent variable, while their performance on a driving test is the dependent variable.

Experiment Types Laboratory Experiments: These take place in either a lab or in a controlled environment setting, which is unnatural for the participants. They attempt to control all variables except the IV. By changing one variable (the IV) while measuring another (the DV) while we control all others, as far as possible, then the experimental method allows us to draw conclusions with far more certainty than any non-experimental method. If the IV is the only thing that is changed then a cause and effect relationship can be found between the IV ad the DV.

Experiment Types (Cont’d) Laboratory Experiments: Strengths Laboratory experiments have high levels of standardisation, and so can be replicated to test for reliability. As laboratory experiments have high levels of control, researchers can be more confident it is the IV directly affecting the DV (cause and effect relationship). It is easier to use sophisticated measuring equipment.

Experiment Types (Cont’d) Laboratory Experiments: Weaknesses As laboratory experiments take place in an artificial setting, it is said that they can lack ecological validity Many laboratory experiments make participants take part in tasks that are nothing like real life ones, so the tasks lack mundane realism Participants usually know they are taking part in an experiment and they may respond to demand characteristics as something about the set-up indicates the aim of the experiment. There could also be an experimenter bias.

Experiment Types (Cont’d) Laboratory Experiments: Evaluation Validity These experiments have high internal validity because controls mean the researcher can be confident it is the IV directly affecting the DV. They have low external validity as it may be difficult to apply the findings to a real life situation. Reliability These have high levels of reliability because controls and standardised procedures allow for full replication. It is usually easy to gain informed consent. Deception can be dealt with through a full debrief. Participants know they are in a study so can withdraw at any time. Ethics Internal validity refers to whether it is the IV directly affecting the DV. External validity refers to the extent to which the findings of the study can be applied to real life settings and to other people outside the sample.

Experiment Types (Cont’d) Field Experiments: Sometimes it is possible to carry out experiments in a more natural setting, i. e. in ‘the field. ’ As with the laboratory experiment, the independent variable is still deliberately manipulated by the researcher. However, it is not possible to have such tight control over variables in the field, but it does have the advantage of being far less artificial than the laboratory.

Experiment Types (Cont’d) Field Experiments: Strengths As field experiments take place in a realistic setting, it is said that they have good ecological validity and reduce experiment effects. As participants will not know they are taking part in a study, there will be little or no demand characteristics so the behavior is more likely to be natural and valid, improving mundane realism.

Experiment Types (Cont’d) Field Experiments : Weaknesses Situational variables can be difficult to control, so sometimes it is difficult to know whether it is the IV affecting the DV. It could also be an uncontrolled variable causing the DV to change. As participants will not know they are taking part in a study, there are issues with breaking ethical guidelines. These include the issues of informed consent and deception Field experiments are difficult to replicate, time consuming, and can be expensive to perform.

Experiment Types (Cont’d) Field Experiments: Evaluation Validity Reliability Ethics These experiments have lower internal validity as the researcher can control some variables, but not all of them. There is stronger external validity than in laboratory experiments due to the “field” setting of the study. These have medium levels of reliability as some elements of the study are controlled with some standardised procedures, but full replication may be difficult to impossible. Researches can gain informed consent from participants, but it is not always possible. Participants may not know they are part of a study which can make debriefing difficult and sometimes impossible. (Also if participants do not know they are in a study their right to withdraw is invalidated).

Experiment Types (Cont’d) Natural (Quasi-Natural) Experiments: Natural/Quasi-Natural experiments may take place in the lab or field. Like other experiments they have an IV but in this type of experiment the experimenter does not directly manipulate the IV. Some IVs are not open to manipulation as some conditions are pre-decided by fixed characteristics. Ex: comparing men and women’s driving skills, they cannot be randomly allocated to be male or female. The IV is naturally occurring. Other examples of pre-existing variables might be age, IQ, position in the family, and social background.

Experiment Types (Cont’d) Natural (Quasi-Natural) Experiments: Strengths As the experiment is located in a natural setting exploiting a naturally occurring IV, the investigator doesn’t intervene, and the study should be high in ecological validity. As participants are usually unaware that a study is taking place, their behavior is more likely to be natural and a valid representation of each person’s behavioral repertoire. This reduces the likelihood of demand characteristics.

Experiment Types (Cont’d) Natural (Quasi-Natural) Experiments: Weaknesses They may be more expensive and time consuming than lab experiments. There is no control over extraneous variables which might adversely affect the results. A cause and effect relationship may be difficult to establish. This makes it challenging for another researcher to replicate the study exactly the same way.

Experiment Types (Cont’d) Natural (Quasi-Natural) Experiments: Evaluation Validity Reliability Ethics These experiments have low internal validity as there is no control over any extraneous variables. Natural experiments have high external validity as they take place in participants’ natural environment. These have low levels of reliability as there is hardly any controls or standardisation and this makes replication very difficult. There are several issues. Informed consent can be very difficult to obtain, depending on the study. People may not know they are part of a study which can make debriefing difficult and sometimes impossible. (Also if participants do not know they are in a study their right to withdraw is invalidated).

Experimental Designs Independent Measures: This design uses different participants for each condition of the experiment.

Experiment Designs (Cont’d) Independent Measures: Strengths Independent measures have no order (practice and/or fatigue/boredom) effects, effects which reduces the chance of demand characteristics. Since independent measures design has the participant only experience one level of the IV, the researcher can use the same stimulus materials.

Experiment Designs (Cont’d) Independent Measures: Weaknesses Independent measures requires more participants to collect sufficient data to determine if there is a cause and effect relationship. Since independent measures design has the participant only experience one level of the IV, participant variables (or individual differences) could occur. This limits comparisons and can affect the validity of the findings.

Experimental Designs (Cont’d) Repeated Measures: This design exposes the same participants to each condition.

Experiment Designs (Cont’d) Repeated Measures: Strengths Repeated measures eliminates participant variables (or individual differences) and allows for comparisons to be made. Since repeated measures design has the participant experience all levels of the IV, fewer participants are needed.

Experiment Designs (Cont’d) Repeated Measures: Weaknesses Repeated measures could limit the researcher’s ability to use the same stimulus materials. Since repeated measures design has the participant experience every level of the IV, order (practice and/or fatigue/boredom) effects could occur. This can also make it easier for the participant to guess the aim(s) of the study (demand characteristics).

Experimental Designs (Cont’d) Matched Pairs: This design matches each participant with someone who is similar to them, and placing them in different conditions.

Experiment Designs (Cont’d) Matched Pairs: Strengths Matched Pairs have no order (practice and/or fatigue/boredom) effects, which reduces the chance of demand characteristics. Since the matched pairs design has the participant only experience one level of the IV, the researcher can use the same stimulus materials. It also tries to control participant variables (or individual differences).

Experiment Designs (Cont’d) Matched Pairs: Weaknesses Matched pairs requires more participants to collect sufficient data to determine if there is a cause and effect relationship. It could be difficult for the researcher to match people.

Self-Reports Define the term self-report. A self-report is a research method, it could be a questionnaire or an interview, which gathers data by asking participants to provide information about themselves.

Self-Reports (Cont’d) Self-Report: Strengths The participants are given the opportunity to express a range of feelings and explain their behavior. The data obtained may be "rich" and detailed, especially with open-ended questions.

Self-Reports (Cont’d) Self-Report: Weaknesses Closed questions often don't give the participant the opportunity to say why they behaved or answered a question in a particular way. Participants may provide socially desirable responses, not give truthful answers, or respond to demand characteristics.

Questionnaires Define the term questionnaire. A questionnaire is a type of self-report which uses written questions to obtain data from a participant. They can be open (What are your views on…? ) or closed (checkboxes).

Questionnaires (Cont’d) Questionnaires: Strengths They can gather information from a large number of people efficiently, can use quantitative and/or qualitative analysis, and it’s easy to replicate. Questionnaires do not require the researcher to be present (reduces investigator effects). Participants may be more willing to reveal personal information.

Questionnaires (Cont’d) Questionnaires: Weaknesses There could be low response rates. Answers may yield a social desirability bias. People could misunderstand the questions. This could reduce the validity of the findings. They lack flexibility since the researcher cannot ask other questions that might arise, and only people who can read/write can participate.

Interviews Define the term interview. An interview is a type of self-report in which questions are asked to a participant and the interviewer records the responses. It can either be structured (a set of questions predetermined), unstructured (questions aren’t decided in advance) or semi-structured (some questions are pre-prepared, however, the interviewer is free to add more during the interview).

Interviews (Cont’d) Interviews: Strengths They tend to be more flexible as the researchers can interact with the participants to clarify any information. The data collected can be detailed. The unstructured format could provide new insights, and sensitive issues can be explored.

Interviews (Cont’d) Interviews: Weaknesses There could be an investigator bias. The data can be misinterpreted. The interview could become time-consuming, causing the participant’s withdrawal. The questions could lead to demand characteristics. The interviewee may be unable to convey their true thoughts, which could lower the data’s validity.