Psychology AS investigations

confounding variable

any variable which varies systematically with the IV, that might potentially affect the DV and confound the results

when asked to define a variable, what must you do?

provide an example

operationalise

Ensuring that variables are in a form that can be easily tested.

standardised procedures

A set of procedures that are the same for all participants in order to be able to repeat the study

why are standardised procedures important

they increase the internal validity and reliability and reduce bias

identify key features of an experiment

there's an IV which is deliberately changed to see if this has an effect on the DV, this permits us to draw causal conclusions

Explain the difference between the aims and hypothesis of a study

aims = a statement of what the researcher intends to find out in a study

Hypothesis = a precise and testable statement about the assumed relationship between variables, make sure to OPERATIONALISE it

external validity

the degree to which the findings of a study can be generalized to other people (population validity), settings (ecological validity), or time (historical validity)

internal validity

the degree to which the observed effect was due to the experimental manipulation rather than other factors such as extraneous and confounding variables

extraneous variables

any variables other than the independent variable that seem likely to influence the dependent variable in a specific study, they are not an alternate IV

mundane realism

the degree to which the experimental situation resembles places and events in the real world

alternative hypothesis

alternate to the null hypothesis, basically saying the IV will effect the DV

null hypothesis

A statement of no effect suggesting no relationship between the IV and DV

Pilot study

A small scale trial run of an experiment to test any aspects of the design, with a view to making improvements.

directional vs non-directional hypothesis

directional - has a clear bias

non-directional - no clear bias

confederate

a person who is given a role to play in a study so that the social context can be manipulated

3 types of experimental design

Repeated measures

independent groups

Matched pairs

repeated measures

All participants take part in all conditions of the experiment

disadvantages of repeated measures

1. the order or conditions may effect performance (order effect) so they may do better on the second condition (practice effect) or they may do worse (boredom effect)

2. when participants do the second condition they may guess the purpose of the experiment which could effect their behaviour

method of dealing with disadvantages of repeated measures

- researchers could use two different tests to reduce practice effect but the two tests must be equivalent

- use counterbalancing

- use a cover story to hide aims of experiment

Independant groups

Participants are allocated to different groups where each group represents one experimental condition

disadvantages of independent groups design

1. the researcher cannot control the effects of participant variables e.g. different abilities of people

2. needs more participants to end with the same amount of data

how to deal with disadvantages of independent groups design

randomly allocate participants to conditions

matched pairs

use two groups of participants but match participants together on key characteristics which are relevant to the study

disadvantages of matched pairs

1. time consuming and difficult

2. not possible to control all participant variables because you can only match them on variables known to be relevant

how to deal with disadvantages of matched pairs

- restrict the number of variables to match on to make it easier

- conduct a pilot study

counterbalancing

A method of controlling for order effects in a repeated measure design by either including all orders of treatment or by randomly determining the order for each subject

2 counterbalancing methods

1. AB or BA - divide participants into two groups and one group does A then B and the other does B then A

2. ABBA - all participants take part in all conditions twice

advantages of conducting experiments in a laboratory

allow researchers to measure research variables more easily makes it easy to control confounding and extraneous variables

disadvantages of laboratory experiments

participants may show artificial behaviour

some research may not be able to be conducted in a laboratory setting

advantages of field experiments

minimises artificial nature of the experiment

allows psychologists to examine behaviour in a huge range of contexts

disadvantages of field experiments

more difficult to control extraneous and confounding variables

difficult for researchers to access full range of equipment eg brain scanning machines

advantages of online research

ability to access large and diverse sample size

cost effective

data analysis is generally easier and quicker

disadvantages of online research

online methods are limited eg questionnaires

ethical issues such as valid consent and risk of harm are difficult to deal with as well as debriefing afterwards

quasi experiment

not a 'true' experiment because the IV is not deliberately manipulated so not possible to draw causal conclusions

2 types of quasi experiment

- natural experiments

- difference studies

natural experiments