5. experimental design

Question 1

experimental conditions

Answer 1

levels/conditions of the IV, eg religions affiliation -> 2 levels, western and eastern

Question 2

controlled conditions

Answer 2

level of an IV in an experiment from which the IV is absent, eg religions affiliation -> 2 levels, western and eastern and NO RELIGION (the controlled condition)

Question 3

placebo

Answer 3

a solution or drug that has no effect but ppt believe it will affect them

Question 4

3 types of experimental design?

Answer 4

• independent measures
• repeated measures
• matched pairs

Question 5

independent measures

Answer 5

a different group of ppts is used for each level of the IV

Question 6

pros of independent measures design

Answer 6

• Used when IV levels reflect different characteristics
  i.e. girls, boys, age, profession
• No order effects : participants only see the experimental condition once
  — unlikely to get bored (fatigue)
  — or to improve on task set
  (practice effect)
  — less likely to work out what the
  study is about and change responses (demand characteristics)

Question 7

cons of independent measures design

Answer 7

• individual differences/participant variables may cause a difference instead of IV

[can minimise this risk by random allocation of participants to IV levels.]

Question 8

repeated measures

Answer 8

same group of ppts in every level of the IV

Question 9

pros of repeated measures

Answer 9

• removes effects of individual differences/participant differences
  [each participant acts as their own baseline.]

Question 10

cons of repeated measures

Answer 10

• Order effects –due to participants repeating the task at least twice
  — Practice effects: practice may improve performance
  — Boredom effects: repeats might make performance worse.
• figure out aims and increase
  risk of demand characteristics
  [Can be avoided by counterbalancing]

Question 11

practice effects

Answer 11

A situation where participants’ performance improves because they experience the task more than once.

Question 12

order effects

Answer 12

consequences of doing tests/tasks more than once

Question 13

boredom effects/fatigue effects

Answer 13

A situation where participants’ performance declines because they experience the task more than once.

Question 14

matched pairs

Answer 14

participants are matched into pairs who are similar (in variables important to the study).
Members of twin pairs split into different groups to perform one IV level only.

Question 15

pros of matched pairs

Answer 15

• order effects removed
• effect of patricipant variables reduced

Question 16

cons of matched pairs

Answer 16

• impossible/time consuming to match pairs exactly
• matching variables might give clues to the study aims - increases risk of demand characteristics

Question 17

counterbalancing

Answer 17

Used to overcome order effects in a RM design.

• Participants split into subgroups, and different groups perform each possible order of levels of the IV.

Question 18

randomised control trials (RCTs)

Answer 18

heavily controlled experiments where participants are randomly assigned to an experimental condition (given a new drug) or a control condition (given a placebo).