Outline in the table below how situational variables can affect the DV. Order effects Time of day Temperature Situational Variables How can it be Extraneous variable How does it affect validity? overcome? Situational variables Something about the situation of the Situational variables can (anything to do with the experiment could act as an EV if it be overcome by the use environment of the has an effect on the DV. For of standardised experiment): time of day, example, poor lighting could affect procedures which temperature, noise levels etc participants performance on a ensure that all memory test participants are tested under the same conditions. Participants variables It may be that the differences Participant variables can (anything to do with differences between the participants cause the be completely removed in the participants): age, change in the DV. For example, one by using a repeated gender, intelligence, skill, past group may perform better on a measures design (the experience, motivation, memory test than another because same participants are education etc. they are younger, or more used in each condition). motivated. Matched pairs (participants in each group are matched) could also be used. Investigator effects: this Leading questions from the Investigator effects can refers to how the behaviour and experimenter may consciously or be overcome by using a language of the experimenter unconsciously alter how the double blind technique. may influence the behaviour of participant responds. For example, This is when the person the participants. The way in the experimenter may provide who carries out the an experimenter asks a verbal or non verbal encouragement research is not the question might act as a cue for when the participant behaves in a person who designed it. the participant. Also known as way which supports the hypothesis.
Outline in the table below how situational variables can affect the DV. Order effects Time of day Temperature Situational Variables Extraneous variable How does it affect validity? How can it be overcome? Situational variables (anything to do with the environment of the experiment): time of day, temperature, noise levels etc Something about the situation of the experiment could act as an EV if it has an effect on the DV. For example, poor lighting could affect participants performance on a memory test Situational variables can be overcome by the use of standardised procedures which ensure that all participants are tested under the same conditions. Participants variables (anything to do with differences in the participants): age, gender, intelligence, skill, past experience, motivation, education etc. It may be that the differences between the participants cause the change in the DV. For example, one group may perform better on a memory test than another because they are younger, or more motivated. Participant variables can be completely removed by using a repeated measures design (the same participants are used in each condition). Matched pairs (participants in each group are matched) could also be used. Investigator effects: this refers to how the behaviour and language of the experimenter may influence the behaviour of the participants. The way in an experimenter asks a question might act as a cue for the participant. Also known as Leading questions from the experimenter may consciously or unconsciously alter how the participant responds. For example, the experimenter may provide verbal or non verbal encouragement when the participant behaves in a way which supports the hypothesis. Investigator effects can be overcome by using a double blind technique. This is when the person who carries out the research is not the person who designed it.
research_methods_booklet_2014-15.docx