Dull Rats and Bright Rats
The aim of this particular study was to examine whether or not experimenter effects can occur in studies of animal behaviour and the null hypothesis suggested was that there would be no significant change in the behaviour of the animals, regardless of the experimenterâ€™s mental expectations. The research hypothesis for this experiment was the â€˜unconscious mental expectationsâ€™ of the student subjectsâ€™ would influence the outcome of the ratâ€™s time trials and would show that the â€˜subjectsâ€™ expectations of their rats would somehow â€˜inadvertentlyâ€™ affect the behaviour of their group of rats.
The independent variable in this ...view middle of the document...
The design used in this study is stated as â€˜a basic two-condition independent measures experimental designâ€™ with the participantâ€™s belief about the relative ability of their group of rats as the independent variable and the dependent variable as the mean (average) number of correct responses per rat per day over a five-day period. This particular type of experimental design uses different subjects in each condition of the experiment, rather than using the same subjects like a repeated measures experiment. The researchers couldâ€™ve chosen this design to base their experiment on as effects such as fatigue would not influence the second condition as the subjects only have to participate in one condition. Also, because the subjects are only being tested in one condition, the subjects would remain naÃ¯ve to the research purpose of the study, thus making the results more valid and reliable as the subjects wonâ€™t compromise the identity of the study and change their behaviour in order to influence the outcome of the experiment.
Some controls that had been established for the study were:
* The rats were placed on a 23-hour food deprivation period prior to the experiment
* The size of the rat groups as well as the gender ratio of males: females in each of the groups (2:3)
* The design of the maze (t-shaped)
* The time period that the experiment was taking place over â€“ five days
The sample was chosen by pairing together students who had similar expectations of how well they thought they would work with the rats and were then randomly separated and each individual was designated a sample group of â€˜maze-brightâ€™ rats or â€˜maze-dull ratsâ€™. The sample of rats was chosen at random however the gender ratio of the rats in each group was kept constant (3 females and 2 males) as well as the age that the rats were (between 64 and 105 days old). This type of sampling used is defined as â€˜opportunity samplingâ€™ as the researchers used participants who were university students studying experimental psychology, so they were: convenient for the researchers to use.
This particular method of sampling is very convenient and economical so it was very time-effective for the researchers to use the students as subjects, instead of wasting time trying to find other suitable participants for their experiment.
The results from this study shows that the rats believed to be â€˜maze-brightâ€™ by their trainers (subjects of the experiment) on average made more correct responses each day than the rats who were believed to be â€˜maze-dullâ€™. The...