Variables
Recap from last lesson

Aims

Hypotheses

IV and DV
Eye on the Exam

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.

Write a directional hypothesis for this experiment (2 marks)
Eye on the Exam
A researcher investigated whether memory for words presented with pictures
was better than memory for words presented without pictures. The researcher
used an independent groups design.
In Condition 1, participants were given a limited time to learn a list of 20 words.
They were then asked to recall the 20 words in any order.
In Condition 2, participants were given the same time to learn the same 20
words, but this time each word was presented with a picture. For example, the
word ‘apple’ was presented alongside a picture of an apple. They were then
asked to recall the 20 words in any order.
State a non-directional hypothesis for this experiment (2 marks)
Eye on the Exam
A psychologist used an independent groups design to investigate whether
or not a cognitive interview was more effective than a standard interview,
in recalling information. For this experiment, participants were recruited
from an advertisement placed in a local paper. The advertisement
informed the participants that they would be watching a film of a violent
crime and that they would be interviewed about the content by a male
police officer.
The psychologist compared the mean number of items recalled in the
cognitive
interview with the mean number recalled in the standard interview.
Identify the independent variable and the dependent variable in this
experiment (2 marks)
Eye on the Exam
Dave, a middle-aged male researcher, approached an adult in a busy street.
He asked the adult for directions to the train station. He repeated this with 29
other adults.
Each of the 30 adults was then approached by a second researcher, called
Sam, who showed each of them 10 photographs of different middle-aged
men, including a photograph of Dave. Sam asked the 30 adults to choose the
photograph of the person who had asked them for directions to the train
station.
Sam estimated the age of each of the 30 adults and recorded whether each
one had correctly chosen the photograph of Dave.
Identify one aim of this experiment (2 marks).
Learning Objectives

To define operationalising of variables

To operationalise given variables

To define and give examples of extraneous variables
Variables

IV and DV

Extraneous Variables

Operationalising Variables
Operationalising Variables

Narrowing down the research focus

How the variables will be measured

For example, in a study looking at
whether eating spinach increases
strength, we could operationalise
strength by measuring….
Your Task
 Complete
the page in your booklet to
operationalise the given variables
Extraneous Variables

Anything other than the independent variable
that could affect the dependent variable

Need to be controlled

Split into random errors and constant errors
Random Errors

Participant’s state of mind

Participant’s level of motivation

Incidental noise

Room temperature

Time of day

Previous experiences on the day of the study, for example…

Control for them by… allocating p’s randomly to the experimental
conditions – random errors should balance out across the conditions
Constant Errors

A failure to randomise experimental conditions

Participant differences – i.e. gender, intelligence, age etc…

Errors of measurement which affect one condition more than
another.
Your task

Complete the section on extraneous variables in
your booklet
Eye on the Exam
Dave, a middle-aged male researcher, approached an adult in a busy street. He
asked the adult for directions to the train station. He repeated this with 29 other
adults.
Each of the 30 adults was then approached by a second researcher, called Sam,
who showed each of them 10 photographs of different middle-aged men,
including a photograph of Dave. Sam asked the 30 adults to choose the
photograph of the person who had asked them for directions to the train station.
Sam estimated the age of each of the 30 adults and recorded whether each one
had correctly chosen the photograph of Dave

Identify one possible extraneous variable in this experiment. Explain how this
extraneous variable could have affected the results of this experiment (4 marks).
Extension

Complete the first set of summary questions in your
booklet (excluding those on ethical issues – we’ll look at
them another time)

Ensure your booklet is up to date – use a textbook to
help you