A biopsychologist studies the role of the brain chemical serotonin ...

  

A biopsychologist studies the role of the brain chemical serotonin in aggression. One sample of rats serves as a control group and receives a placebo. A second sample of rats receives a drug that lowers brain levels of serotonin. Then the researcher tests the animals by recording the number of aggressive responses each of the rats display. For the data below, is there a significant effect of the drug on aggression? What, if any, role does serotonin has in aggression? Use an alpha level of α = .05. (Note: is this a one-tail or two-tail test?)

Lowers Serotonin        Control

5                                       3

8                                      6

15                                    5

16                                    6

6                                      8

9                                       4

                                        7