aims, hypotheses and variables

aim definition

• a general statement

• that covers a topic, theory or concept

• that will be investigated

hypothesis definition

• a testable statement

• written as a prediction of what is expected

• by a researcher from the study

alternative hypothesis definition

• hypothesis that predicts the effect of the IV on the DV

• hypothesis of difference

operationalising the IV - alternative hypothesis

• breaking the IV down into 2 separate conditions

• e.g. participant in condition 1 drinks 200ml of water, participant in condition 2 drinks 200ml of coffee

operationalising the DV - alternative hypothesis

• providing the total number of total possible correct answers

• and identifies how participant performance is measured

• e.g. measuring the number of recalled items, 15 possible correct answers, how many items are recalled

directional hypothesis definition

• hypothesis which predicts the direction of the difference

• e.g. condition 1 will out-perform condition 2

non-directional hypothesis definition

• hypothesis that doesn’t predict the direction of the difference, just that there will be a difference

• e.g. there will be a difference between condition 1 and condition 2

null hypothesis definition

• hypothesis where the IV has no effect on the DV

• all published psychological research must include a null hypothesis

how the null hypothesis works

• a null hypothesis states conditions will have no difference between them

• after the experiment, if there is no difference, the NH must be accepted

• if there is a difference, then the NH is rejected and the AH can be accepted

how hypotheses for correlational investigations work

• they are written the same way as experimental hypotheses except there is an idea of positive/negative/no relationship instead of difference

independent variable definition

variable in an experiment that is manipulated (e.g IV is drink, condition 1 = coffee, condition 2 = water)

IVs in lab experiments

a lab experiment MUST use an IV that has been implemented by the researcher e.g loud music, silence - it cannot be naturally occurring (gender, age, ethnicity)

quasi/natural experiments

experiments that use a naturally-occurring IV

dependent variable definition

variable that is measured (e.g. activity levels between coffee and water)

extraneous variables definition

• any variable that intrudes upon and adversely affects the DV (time of day, temperature, mood)

• these variables are controlled by the researcher so the experiment remains objective and unbiased

demand characteristics definition

• instances of interaction/interference between the researcher process and the participant

examples of demand characteristics have on an experiment

• participants picking up on cues of the research can cause their performance to become contrived

• unnatural settings (labs etc) can change the way participants respond to the experiment

• investigator effects can cause participants to behave in different ways towards the researcher

how to control demand characteristics

• use single-blind procedure

• the participant doesn’t know which condition they’ve been assigned to

• meaning they aren’t able to respond according to what they think they are being assessed on

investigator effects definition

interference in the research process caused by the researcher’s presence/behaviour

example of characteristics that can cause investigator effects

• age

• gender

• ethnicity

• accent

• tone of voice

• non-verbal communication/body language

how to control investigator effects

• using a double-blind procedure

• this means that the participants don’t know which condition they’ve been assigned to

• and the researcher is not able to exercise any form of bias during the procedure or when analysing results

randomisation definition

the deliberate avoidance of bias by the researcher to keep the research as objective as possible

extraneous variable definition

• extraneous variables are any variable that intrudes upon and adversely affects the DV e.g:

  • time of day

  • temperature

  • mood

why are extraneous variables controlled?

so the research remains objective and unbiased