Psychology Life Hack of the Week Avoid the ‘sidewalk shuffle’ by looking intently beyond the oncoming person’s shoulder or between the heads of two oncomers. They will move for you. (Knorr, 2016)

Review your knowledge of Year 1 research methods so far … https://create.kahoot.it/kahoots/my-kahoots

Year 1 Research Methods: Experimental Design and Control of Variables Identify and distinguish between the different types of experimental design. Identify strengths and weaknesses of each design. Identify and explain the control of variables in psychological investigations.

What is ‘experimental design’? What do these pictures suggest ‘experimental design’ is? Identify the type of design suggested by each picture.

What is ‘experimental design’? Experimental design refers to how participants are allocated to the different conditions (or IV groups) in an experiment. Do they do one condition? Do they do all of them? Don’t confuse experimental design with types of experiment!!!

Three Types of Design: 1. Independent groups: One group of participants do condition A and a second group do condition B. 2. Repeated measures: The same participants take part in all conditions of the experiment. 3. Matched pairs: Two groups of participants but they are related to each other by being paired on participant variables relevant to the study.

Task – page 2 Draw the three types of experimental design in the spaces provided. Condition A Condition B Which design? A) A researcher is interested in whether alcohol has an effect on memory. One group of participants are given a list of words to learn and then given an alcoholic drink. The other group is given the same list of words, and a glass of water. The number of words they can remember is recorded. B ) A scientist has developed a drug which he believes will increase IQ. He has two groups of participants; one group he gives the drug to, and the other he gives a placebo to. After two weeks, he tests their IQ. To try and avoid any participant variables, he ensures that he has an equal number of men and women in each group, and that the participants are of similar ages, intelligence and social background.

Task – page 3 1. Independent groups 2. Matched pairs 3. Repeated measures 4. Repeated measures or independent groups 5. Independent groups or matched pairs 6. Repeated measures

Task – page 4 Fill in the blanks to determine the strengths and weaknesses of each type of experimental design. Challenge: How might the limitations of each design be overcome?

Extraneous variables Extraneous variables Extraneous variables A Confounding variables CV varies systematically with the IV – it is present in one condition and not the other. This means we cannot be sure if changes in the DV are due to the IV or CV. Extraneous variables (EVs) are ‘nuisance’ variables that may affect the DV if not controlled. They do not vary systematically with the IV. Extraneous variables Extraneous variables Extraneous variables Extraneous variables Extraneous variables Extraneous variables Extraneous variables

Example: A study on whether noise makes people more likely to make mistakes in a memory test (IV causing DV) – if those in the experimental group had all had late nights the night before, mistakes could be due to tiredness (CV) rather than noise (IV).

Variables and Control Read about EVs and CVs on page 5 of the handout and then complete the following question: Explain the difference between extraneous and confounding variables. Include key terms/details and highlight how they differ. Extraneous variables (EVs) are ‘nuisance’ variables that might affect the dependent variable (DV) if not controlled. EVs do not vary systematically with the independent variable (IV). In contrast, a confounding variable does vary systematically with the IV- it is present in one condition and not the other. This means we cannot be sure that any change in the DV was due to the IV. Finished? Complete the sort task on page 6.

Sort the EVs into participant and situational variables: Variables and Control Sort the EVs into participant and situational variables: Challenge: Which of these might be the most difficult to control and why?

Demand Characteristics Any cue from the researcher or research situation that may reveal the aim of the study. May lead to a ‘screw-U’ or ‘please-U’ effect.

Investigator Effects Any effect of the investigator’s behaviour on the outcome of research (the DV) Task – page 6-7 NB: There are no right answers!!

Controlling Variables – page 8 Read about the problems with experimental control and try to find a method of control for each. Choose from the ‘solutions’ placed around the room.

Controlling Variables Problem Variable Method of Control Order effects Participant variables Investigator effects – design Investigator effects and situational variables Counterbalancing Random allocation of participants to conditions Randomisation Standardisation

In turns, choose a card from the pack. Describe the term on the card WITHOUT using the actual term. The person who correctly guesses the term, wins the card. If no one guesses the term or if you don’t know what it means, place the card back in the pack. As a group, discuss those terms you are confident about and those you need to review.

1. A researcher carried out an experiment to investigate misleading information. Participants were shown a photograph in which a man and a woman were talking. The photograph was then taken away and the participants were asked questions about it. Participants were randomly allocated to condition one or condition two. Participants in condition one were asked: Question A “How old was the youth in the photograph?” Participants in condition two were asked: Question B “How old was the man in the photograph?” Name an appropriate experimental design which could be used in this experiment. Explain why a repeated measures design would be unsuitable to use in this experiment. (1 mark + 3 marks) 2. A psychologist carried out an experiment using an independent groups design. The psychologist wished to investigate the effectiveness of a strategy for memory improvement. In one condition, participants were taught a memory improvement strategy. In the other condition, participants were not taught this memory improvement strategy. All participants were asked to memorise 10 pictures of familiar objects. For example, the first was a doll, the second was an apple. All participants were then given 50 pictures each, and asked to select the original 10. Explain one strength and one limitation of using an independent groups design. (2 marks + 2 marks) 3. Explain how you can overcome limitations of independent groups design. (2 marks) 4. Explain how counterbalancing can overcome limitations of repeated measures design.