In an initial experiment adult laboratory rats are tested in a working memory task. In the task rats learn to retain visual information over a delay period. Performance in the task is measured as the percentage of correct choices at each delay length (5, 10, 15 and 20 seconds). Within a single testing session (120 trials) all animals are exposed to each of the delay lengths with the order of delays randomized. (Example order: 15 sec, 5, 20, 10, 5, 15, 20...etc.)
After animals learn how to perform the task the following experiment is conducted: All animals underwent four sequential days of testing in separate experimental sessions. Prior to each testing day all animals received a single injection of the drug fakeium. The doses administered were 10, 25, 50 and 100 mg/kg and a Latin square was used to generate a counterbalanced dosing order.
In a replication experiment the participant variable of age was added, and the entire experiment (as described above) was repeated in three separate groups of rats with age categories of juvenile, young adult, and old adult.
Select ALL choice options that accurately describes the experimental design used in the replication experiment.
*Hint: For this question there exactly three of the choice options that must be selected for the answer to be correct.
mixed group design
independent group design
