Lesson 5

Extraneous variables Extraneous variable (EV) is a general term for any variable, other than the IV, that might affect the results (the DV). These are also known as random errors – they cannot be predicted and are such things as a participants state of mind Where EVs are important enough to cause a change in the DV, they become confounding variables. Confounding variables also known as constant errors effect the dependent variable in a consistent way so are a more serious problem, An example of a constant error is in a repeated measures when the order of conditions is not reversed. If a study is affected by a confounding variable the result of the study is not valid since cause and effect cannot be seen.

How can we minimise extraneous variables? Replicable procedure Standardised instruction Controlled room environment Reliable measurement Consistency between the conditions

Practice exam question In a laboratory experiment involving a medical consultation role-play, participants were randomly allocated to one of two conditions. In Condition A, a doctor used diagrams to present to each participant a series of facts about high blood pressure. In Condition B, the same doctor presented the same series of facts about high blood pressure to each participant but without the use of diagrams. At the end of the consultation, participants were tested on their recall of facts about high blood pressure. Each participant was given a score out of ten for the number of facts recalled.   In this case, the psychologists decided to use a laboratory experiment rather than a field experiment. Discuss advantages of carrying out this experiment in a laboratory. (4 marks)

Example answer (4 marks) One advantage of carrying out an experiment in a laboratory is that you have high control over extraneous variables. The lab setting meant that extraneous variables could be minimised. In this experiment, outside factors such as waiting time, noise and stress (which would be difficult to control in a field experiment) were removed. This is an advantage as we are able to infer cause and effect in the experiment. Another advantage is that carrying out an experiment in a laboratory is more ethical. The testing of memory in a field experiment would have involved ethical issues including deception of patients or withholding of information.

Peer review

What happens in the peer review process? Role of peer review The primary purpose of peer review is to ensure that the papers published are valid and unbiased. What happens in the peer review process? A paper is submitted to a journal and evaluated by several reviewers.   After critiquing the paper the reviewers submit their thoughts to the editor.  Then, based on the commentaries from the reviewers, the editor decides whether to publish the paper, make suggestions for additional changes that could lead to publication, or reject the paper.

Why bother? “Peer review is one way (replication is another) science institutionalises the attitudes of objectivity and public criticism.  Ideas and experimentation undergo a honing process in which they are submitted to other critical minds for evaluation.  Ideas that survive this critical process have begun to meet the criterion of public verifiability” (Stanovich, 2007, p. 12).

Why bother? Research proposals will be scrutinized to check it is robust To ensure it can contribute to already existing knowledge Ethics approval Encourages academic debate, openness and communication Ensure there is no bias Appropriateness of conclusions drawn Ensure it is worth dissemination- journals Consider wider implications Find any errors Ensure it can be repeated

What does peer review involve? Here are some of the aspects of the research that are scrutinised: Originality of the research The appropriateness of the overall research design, including the methods used to collect and analyse the data Ethical issues The sample technique used Potential sources of bias The operationalization and control of key variables The reliability, validity and interpretation of the findings The appropriateness of any conclusions drawn

Task: Peer review this study George has a feeling that people who own dogs are more caring than people who own cats. The reason why he thinks this may be the case is because he believes that dogs take more care than cats and therefore will attract those who have a more caring personality. He decides to ask some of his friends if they agree with him. He tells his friends that he thinks dog owners will be more caring than cat owners and why. Five of his friends agree with him. They suggest other reasons why dog owners may be more caring than cat owners that George had not thought of. Therefore, George concludes that he is right. Dog owners are more caring than cat owners. George consequently posts an article on an online forum stating that dog owners are more caring than cat owners with a discussion of all the reasons why this may be, incorporating the views he has collected from his friends.

Strengths of peer review

Bias Reviewer Publication Reputation

Past exam question on peer review A. Outline what is meant by the term peer review in psychological research (2 marks) B. Explain why peer review is important in psychological research. (5 marks)

Mark scheme – a) AO1 =2 marks Peer review is the process by which psychological research papers, before publication, are subjected to independent scrutiny by other psychologists working in a similar field who consider the research in terms of its validity, significance and originality. 0 marks for ‘other psychologists look at the research’. 1 mark for a very brief outline eg ‘other psychologists look at the research report before it is published.’ One further mark for elaboration

Mark scheme – b)

Psychological report writing

Reporting psychological investigations When a psychologist carries out research, they must write it up in a report. This report always follows the same format. Define the following: Abstract Introduction Method Results Discussion References Give student handout

Exam question practice Imagine that you are writing up the report for this experiment. What is the purpose of the abstract in a psychological report? [2 marks] Award one mark for a brief answer (‘the purpose of an abstract is to provide a short summary of the study’) and two marks for a detailed answer referring to providing sufficient information to establish if the full report is worth reading.