an experiment is an:
investigation which looks for a cause- and effect relationship
what does the researcher investigate during an experiment?
how the one way variable (IV) is responsible for the effect in another (DV)
extraneous variables are?
any other variable that might affect the DV
the control condition is?
the absence of the experimental variable.
the levels of the IV being compared
experimental conditions
experimental design?
the way that participants are used in different levels of the IV. may be allocated to all or only one of the levels of the IV
independent measures design?
a separate group of participants is used for each experimental condition / level. this means that the data for each level of the IV is independent because it isn’t related to any other data (since it comes from different people)
IMD strengths?
- Participants only encounter the experimental setting once, which reduces demand characteristics as they are unlikely to notice clues that might tell the aim of the experiment
IMD weaknesses?
- Individual differences between groups, which can be reduced by random allocation of participants to different groups
repeated measures design?
the same group participates in each level of the IV.
RMD strengths?
- Each participant acts as their own baseline. individual differences (participant variables) are unlikely to bias the findings.
participant variables?
individual differences between participants (age, gender, personality, ect.) that could possibly bias the findings
RMD weaknesses?
- Order effects. doing something over and over may cause a participant to improve (the practice effect), or participants could get bored (the fatigue effect)
how can a researcher prevent order effects?
- counterbalancing, by dividing a group into 2 and one half will do A to B, while the other half does B to A.
matched pairs design?
participants are matched into pairs who are similar in ways that are relevant to the experiment (age, gender, intelligence, ect.) different groups are then used for each level of the IV, with one participant from each pair being in each level of the IV
laboratory experiments?
an experiment that is conducted under highly controlled conditions (not necessarily a lab) where accurate measurements are possible. artificial surroundings as the participants are not in their usual environment for the behavior that they are doing. strict controls
evaluating lab experiments (3!)
- controls and standardization, which ensures the procedure for each participant is kept the same. (easy to replicate + raises reliability)
- both controls + standardization help to make the findings of the experiment reliable
- controlling variables also improved validity
field experiments?
still an experiment (as it has controls and variables) but is conducted in the participants normal environment
evaluating field experiments (2!)
- harder to control variables and standardize procedures
- validity might be improved because the participants are performing a task that seems normal in a familiar environment
field vs lab evaluation
lab experiments do not generalize to other settings as well as those from field experiments as the participants are not doing tasks in their normal environment in the way participants in field experiments are. this is a problem of ecological validity, and field experiments are often > in terms of EV than lab exps.(but not always)
natural experiments?
not a true experiment because the researcher cannot manipulate the levels of the OV. the differences occur even in the absence of an experiment
evaluating natural experiments (1!)
- less opportunity to control & standardize situations.
(possibility for uncontrolled variables, which lowers the validity of the findings)
