2. Experimental Method Section B questions G544

Core Studies Loftus & Palmer Maguire

Baron-Cohen Piliavin

Savage-Rumbaugh Reicher & Haslam

Samuel & Bryant Rosenhan

Bandura Thigpen & Cleckley

Freud Griffiths

Dement & Kleitman Milgram

Sperry

Section B

1. Briefly outline the experimental method used in Psychology (4 marks)

2. Describe 2 laboratory experiments in Psychology (8 marks) 3. Discuss strengths and limitations of using the experimental

method to investigate behaviour. Use examples of psychological research to support your answer (12 marks)

4. Compare laboratory experiments with field experiments. Use examples of psychological research to support your answer

5. Discuss the extent to which psychology can be a science (8 marks)

Brainstorm • Write down everything you can remember about the

experimental method

Key features of the experimental method • Theory: The aim of an experimental is to test a hypothesis

(prediction) with the aim of disproving or supporting it. • Test: In order to test the prediction, it has to be established

that one variable (thing) has a measurable effect on another variable (thing).

• Control: The study must be conducted under controlled conditions so that the researcher can identify that the effect that has been found is due only to an identified variable and not to other factors that were not tested.

• Replication: In order for support for a theory to be retested it is vital that any experiment can be replicated (imitated with the same results) by others. This means that the method must be identified precisely and be standardised so that it can be imitated.

Key steps in an experiment 1. The experimenter comes up with a hypothesis 2. The experimenter designs an experiment to test that

hypothesis3. The experimenter manipulates one factor (the IV) that s/he

has identified in his hypothesis as being likely to cause a particular effect.

4. The experimenter measures the effect of this manipulation (DV).

5. Other variables are controlled. 6. The experimenter analyses the difference in the mean results

obtained in each condition. 7. If a significant difference is found between means, this

supports the alternative hypothesis. If no significant difference is found, the null hypothesis is retained.

Strengths Limitations -Test hypothesis by manipulation of IV

-Scientific: follows standardised procedures > enables replication

-Control over extraneous variables

-Produces quantitative data which can be statistical analyses to ensure meaningful comparison.

-Low ecological validity – removed from real life

-Small sample reduces generalisability

-Causes stress/anxiety to participants (ethical issues)

-Doesn't collect qualitative data therefore reductionist.

Laboratory Experiment

Nature & Use IV manipulated to observe the effect on DV, under controlled conditions.

Advantages Establishes causal relationships Allows for replication Good control over confounding

variablesDisadvantages Artificiality: Mundane realism and

experimental realism The effects of being observed:

Demand characteristics, (participants) evaluation apprehension (researcher)

Field Experiment

Nature & Use Investigate causal relationships in more natural surrounding

Advantages • Establishes cause and effect relationships• Allows for replication• Behaviour of participants more typical

than in a laboratory experiment, high external (ecological) validity• Avoids some participant effects

Disadvantages • Low in internal validity, poor control• More time consuming

Quasi (Naturalistic) Experiment

Nature & Use IV not directly manipulated Naturally occurring

Advantages Participants behave naturally Investigates the effects of independent

variables that it would be unethical to manipulate

Disadvantages Participants not allocated at random to conditions

Difficult to identify what aspects of the independent variable have caused the effects on behaviour

Activity 3 Strengths & Weaknesses of Experimental Method EXPERIMENTS

Strength Weaknesses

3. Experimental Design

Experimental: Independent Groups Definition Two (or more) groups of participants,

one for each condition.

Advantages •Avoids order effects •Participants cannot guess the purpose and of the experiment therefore reduces demand characteristics.

Disadvantages •Needs more participants •Lacks control of participants variables

EG:

Experimental: Matched Participants

Definition Participants matched on key participant variables

Advantages •No order effects•Participants variables partly controlled•EV well controlled

Disadvantages •Matching is difficult

EG:

Experimental: Repeated Measures

Definition Same participants in each condition

Advantages •Good control for participant variables•Fewer participants •Removes pts variables

Disadvantages •Order effects (e.g. Boredom, practice) •Participants guess the purpose (DC)

EG:

Activity 5 Strengths & Weaknesses of Experimental Design

Strength Weaknesses

IM

RM

MP

4. Aims & Hypothesis

Research

Definition The process of gaining knowledge through the examination of data derived empirically or theoretically.

Reasons for using To produce objective facts

Aims

Definition The stated intention of a study

Reasons for using

To be clear about the purpose of a study

there will be an effect of x on y

Experimental (alterative) Hypothesis

Definition A statement of the relationship between the IV and DV

Reasons for using

An alternative to the null hypothesis (accept/reject)

Null Hypothesis

Definition An assumption that there is no relationship (difference, association, etc) in the population from which a sample is taken with respect to the variables being studied.

there will be no effect of x on y

Directional Hypothesis

1 TAILED Definition Predicts the effect/relationship

Reasons for using

Previous research suggests the direction

Non-directional hypothesis

2 TAILED Definition Does not predict the direction

of the effect/relationship

Reasons for using

-Allows for a difference/relationships occurring in either direction-Previous research has been inconclusive

Activity 6Generating Hypothesis Generate a hypothesis for each of the questions:• What are “football hooligans” really like?• Do children play differently at different ages?• What are the effects of caffeine on attention and concentration?

1. Identify the independent variable (IV) and the dependent variable (DV) from each hypothesis.

2. Identify whether your hypotheses are one tailed or two tailed (remember one-tailed hypothesis predicts the direction of the effect of the IV on the DV, whereas a two-tailed hypothesis does not).

3. Write a null hypothesis for each of the experimental hypotheses.

Activity 7Null Hypothesis

Devise a suitable null and experimental hypothesis for the following:

1. An investigator considers the effect of noise on students’ ability to concentrate and complete a word-grid. One group only is subjected to the noise in the form of a distractor, i.e. a television programme.

2. An investigator explores the view that there might be a link between the amount of television children watch and their behaviour at school.

Activity 8Hypothesis

Read through these examples of alternative hypotheses, and identify whether each is one- or two- tailed:

1. There will be a difference in scores on an intelligence test

between people who eat fish and those who do not eat fish. 2. There will be a relationship between extroversion and

introversion and a preference for loud music3. People will remember more words in a foreign language if

the information is presented in picture form, rather than as words alone.

5. Variables

Variables

Independent Variable

•Manipulated by the experimenter•Create different conditions

Dependent Variable

•Measures the consequence of IV manipulation

Activity 9IV & DVIdentify IV, DV in the following them in the following examples. Remember:• The IV depends on the DV• The IV is manipulated by the experimenter or varies naturally• The DV is one we measure 1. Long-term separation effects emotional development more

than short-term separation2. Participants conform more when the model is someone

they respect. 3. Participants remember more words before lunch than after

lunch. 4. Boys are better than girls at throwing balls. 5. Physical attractiveness makes a person more likeable.

Extraneous Variables• Situational variables are characteristics of the environment in

which the experiment is being conducted which may have an effect on the results. The nature of these variables is very much dependent on the nature of the experiment but temperature, time and humidity could all be situational variables.

• Person or Subject variables are inherent characteristics of the Experimental Unit that might affect outcomes. Hence examples of subject variables might include age, gender and other demographic details (among subjects) and x, y and z (among objects) although this is very much dependent on the object in the experiment.

• Experimental variables are characteristics of the experimenter or the experimental team which might influence how the experiment is conducted, or how the experimental subject responds/behaves in the experimental setting. There is a wide definition for these variables and they may include age, gender, qualifications, etc.

Extraneous Variables• Situational variables : Women shown the most romantic

proposals are in a warmer room. • Personal Variables: What if the women shown the most

romantic video clips are also more romantic in nature than the other women?

• Experiment/Researcher Variables: What if the experimenter was really nice to one group and he was very gruff with the other groups?

NB extraneous variables are only important if they are present for one group and not the other. If all of your subjects are

exposed to the same extraneous variable (like if Josh was nice to all the subjects), then it won't change your dependent variable and it's not considered an extraneous variable.

EXTRANEOUS VariablesVariables other than the independent variable that may bear any effect on the behaviour of the subject being studied. Three main types

1. Subject variables: age, gender, health status, mood, background, etc.

2. Experimental variables are characteristics of the persons conducting the experiment which might influence how a person behaves. Gender, the presence of racial discrimination, language, or other factors may qualify as such variables.

3. Situational variables: Air temperature, level of activity, lighting, and the time of day.

Confounding Variables• A confounding variable or factor is also sometimes referred to

as a confounder or a lurking variable.• It is a "hidden" that affects the variables in question but is not

known or acknowledged, and thus (potentially) distorts the resulting data.

• This hidden third variable causes the two measured variables to falsely appear to be in a causal relation.

• An experiment that fails to take a confounding variable into account is said to have poor internal validity.

Controlling EV

It is necessary to control extraneous variables so that results are not undermined by their effect (become confounding):

1. Control: Ensuring that an extraneous variable remains the same for all experimental units in the experiment. This requires that you are aware of the extraneous variable during the design stage and that you can control it.

2. Constant: Balance the variable across experimental groups This enables comparisons to be made between experimental units on the basis of the effect of the variable.

Activity 10Extraneous Variables Identify the IV and DV • Operationalise variables • Identify EV

1. A psychologist wants to investigate whether students who complete their 4 hours of independent study per week do better in the psychology exam than those students who only complete 1 hour per week...

2. An experiment to see if recall on a memory test is affected by time of day

3. Does drinking coffee whilst revising improve exam results?4. An experiment to investigate the effects of fatigue on

reaction time

Activity 11Independent Variables in Core StudiesLoftus & Palmer

Samuel & Bryant

Bandura

Piliavin

Activity 12Dependent Variables in Core StudiesLoftus & Palmer

Samuel & Bryant

Bandura

Piliavin

6. Operationalisation

‘Eating spinach affects performance’

Operationalisation

•Variables in a form that can be tested (operations)

•How hypothesis will be tested

Both IV and DV need to be precisely operationalised, otherwise, the results may not be valid and cannot be

replicated.

Activity 13Operationalisation

Here are some research ideas. For each one, identify the IV & DV and suggest ways in which each could be operationalised:

1. Do people remember more about a topic they are interested in that about one in which they have little interest?

2. Are there gender differences in the amount of aggression shown by children in play?

3. Are neurotic people more likely to suffer from phobias?

7. Sampling Method

Sample Definition Selected to be representative of the

population

Evaluation May be biased ,therefore can’t generalise

PopulationDefinition The group of people whom the sample

is drawn

Random sampling

Definition Every member of the population has an equal chance of being selected

Advantage

Disadvantage

Participants for Psychological

Research

Volunteer Sample Self Selected

Definition Participants become part of a study by volunteering

Advantage

Disadvantage

Are you available?

Opportunity Sample

Definition Selecting people who are more easily available

Advantage

Disadvantage

Activity 14Target Population

Identify an appropriate target population for each project below. You would select your research sample from this population.

1. To discover whether there are enough youth facilities in your community.

2. To discover whether cats like dried or tinned cat food. 3. To discover whether children aged between 5 and 11

watch too much violent television. 4. To discover the causes of anxiety experienced by

participants in research studies.

Activity 15Sampling

Find a study to illustrate volunteer sampling and another one to illustrate opportunity sampling. (Clue: Most of the studies you have covered used a volunteer sample, whereas some of the studies have used opportunity samples).

1. Why do you think volunteers are more likely than non-

volunteers to be sensitive to the demand characteristics of a study?

2. When would you not expect to find evidence of participant reactivity?

3. Is honesty the best policy? Would demand characteristics be reduced if both participants and experimenters knew the true aims of the experiment?

Activity 16 Sampling in Core Studies

Stated Y/N

If stated, which one?

If not stated, which should?

Loftus & Palmer

Milgram

Maguire

Griffiths

8. Factors associated with research design

a. Operationalisation b. Standardisation c. Control of variables d. Pilot studies

‘Eating spinach affects performance’

Effects validity and replicability

Pilot study Research is expensive (time +

money). To establish weather a design works, that pts understand the instructions, that nothing has been missed out, and that pts are

able to do what is asked, a pilot study (trial run, small scale) should be

undertaken.

Any variables that change between conditions, other than the IV...

Control of Extraneous Variables

Experimental Control Using techniques to ensure that extraneous variables are eliminated

Extraneous/ confounding variables

Hold constant or eliminate

Random Allocation Participants to experimental groups; allocate items on a test

Counterbalancing Order effects balanced to make sure each condition comes first or second in equal amounts (ABBA)

Standardised procedures

A set of procedures that are the same for all participants. To enable replication.

Control of Investigator Variables (effect) Anything that investigator does which has an effect on the participant’s

performance other than what was intended

Double blind The investigator does not know the purpose of the experiment, to prevent expectations influence the participant’s behaviour

Standardised instructions

A set of instructions that are the same for all participants. To avoid investigator effects.

Control of Participant Variables (effect) Anything that has an effect on the participant’s performance other than

what was intended

Single blind Deception to prevent the participants knowing the experimental aim

Placebo conditions

Control group thinks it is receiving the experimental treatment

Demand Characteristics

A demand characteristic is a subtle cue that makes participants aware of what the experimenter expects to find or how participants are expected to behave.

Standardised instructions

A set of instructions that are the same for all participants. To avoid investigator effects.

Investigator effect: Anything the investigator does which has an effect on a participant’s performance in a study

other then what was intended.

Interviewer bias The same in an interview situation, through, for example, leading questions and the ‘Green-spoon’ effect

Experimenter bias

The effect of an experimenter’s expectations, communicated unconsciously, on a participant’s behaviour

Control Group

In the design of experiments, treatments are applied to experimental units in the

treatment group. In comparative experiments,

members of the complementary group, the control group,

receive either no treatment or a standard treatment.

Standardisation

Instructions Pts told what to do in

exactly the same way.

Procedures Pts treated in exactly

the same way.

Activity 17Control of Variables in Core Studies

Well Controlled Confounding

Loftus & Palmer

Samuel & Bryant

Bandura

Piliavin

9. Reliability of Measurement

10. Validity

Generalisability

The findings of any particular study should

apply to the whole population

Types of Validity

Experimental

Internal

External

MeasureConcurrent

Content

Validity: The legitimacy of a study Internal Validity

The extent to which the a measurement technique measures

what it is supposed to

Reasons for low internal validityDemand Characteristics: Features of an experiment the elicit a particular response form participants.Participant reactivity Extraneous variables not controlled (CV), act as an additional IV.Mundane realism: Do measures used generalise to real life > contribute to external validity

External Validity

Validity outside of the research situation,

extent to which findings can be

generalised

Assessing external validity How representative is the sample of participants of the population to which the results are to be generalised? Population VDo the research setting and situation generalise to a real-life setting or situation? Ecological VDo the findings generalise to the past and to the future? Historical V

Experimental

Internal

Extraneous

Mundane Realism

External

Ecological Validity

Population Validity

Historical Validity

Extraneous Variables

Situational Variables Participant Variables Investigator Effects

Demand CharacteristicsParticipant Effects

Participant Reactivity

Participant reactivity: The fact that participants react to cues in an experimental situation

Hawthorne Effect Increased attention becomes a confounding variable

Demand Characteristics

Features of an experiment that a participant unconsciously, responds to when searching for clues about how to behave. A confounding variable.

Social Desirability bias

The desire to appear favourably

Validity of Psychological Measure

Concurrent Validity

How well does the measure agree with existing measures?- Test using old and new tests

Content Validity

Does the method used actually seem to measure what you intended? - Use a panel of experts

Measure

Concurrent

Content

Activity 18 Ecological Validity in Core Studies

High/Low Evidence

Loftus & Palmer

Samuel & Bryant

Dement & Kleitman

Milgram

11. Ethical Issues

11. Ethical Issues Deception Informed consent Psychological harm

Informed consent Difficulty debriefing Privacy

Confidentiality

11. Dealing with Ethical Issues

Presumptive…

A

B

C

Prior…

Dealing with informed consent

• Presumptive consent: Ask for others’ opinion and presume participants feel the same way.

• Prior general consent: Get participants to agree to take part in a number of studies, one of which they will be deceived in.

11. Dealing with Ethical Issues

Dealing with deception

• Debriefing: Inform participants of true nature of the study after it is conducted and allow them to discuss their feelings.

• Right to withhold information

• Cost and benefits: Deception is acceptable if the benefits are sufficient.

11. Dealing with Ethical Issues

Dealing with protection from psychological harm

• Anticipating harm and stopping

• Using role-play

• Use of questionnaires: Ask people how they would behave.

• Debriefing

Activity 19 Ethical Issues in Core Studies

Informed Consent

Deception RTW Debrief

Loftus & Palmer

Samuel & Bryant

Dement & Kleitman

Milgram

12. Dataa. Type of datab. Descriptive Statisticsc. Inferential Statistics

Data Collection Quantitative

Data Easy to analysis

Produces neat conclusions

Oversimplifies reality

Qualitative Data

Represents the complexity of human behaviour

Provides rich data

More difficult to detect patterns and reach conclusions

Subjective, affected by personal expectations and beliefs

Descriptive Statistics

1. Measures of central tendency2. Measures of dispersion 3. Graphical representation

2,4,4,5,6,6,7,78,8,8,8,8

9,10,11,11,12

Measures of Central Tendency Mean: Add

values, divide by number of

values

Makes use of all the data

Can be misrepresentative if there are extreme values.

Median: Middle value in an

ordered list

Not affected by extreme scores

Not as ‘sensitive’ as the mean

Mode: The most common value(s)

The mist common value(s)

Not useful when there are several modes

Measures of Dispersion

• Measures of dispersion

• the range

• standard deviation

Measures of DispersionRange Highest to

lowest Easy to calculate

Affected by extreme values

Standard Deviation

SD measures the amount of variation or dispersion from the average.

Precise, all values taken into account

Harder to calculate

Graphs & Charts

Histogram Graph showing continuous frequency data with a true zero e.g Exam results 0-30marks

Bar Charts Graph showing frequency data; data need not be continuous e.g. Categories

Scattergraph For correlations. Scatter of dots; each dot represent one case

13. Improvements & Future Research

Improvements

Indentify a limitation andsuggest how you makeimprovements to theinvestigation:

Example: • Sample • Method • Validity • Reliability • Ethics

Future Research

1. If you were to progress research in this area what would you do next?

• Think about changes that you could make to your stimulus

• Could you use a different method?

2. What implications does your research have on society? What group would benefit from knowing this information (application)

3. Does this study have real life validity?

14. Writing a procedure for Experiments

1. Decide aim, research question and alternative/null hypothesis

2. Plan procedure, including obtaining ethics approval, choosing experimental design, operationalising the hypothesis, preparation of materials and deciding sampling method.

3. Obtain sample and make arrangements for conduct of study 4. Obtain informed consent from participants 5. Allocate participants to experimental conditions and give

instructions. 6. Participants follow experimental steps (data collected) 7. Thank and debrief participants 8. Analysis data, produce conclusions9. Write report of practical investigation