Date of Award


Degree Type


Degree Name

Master of Science


Psychological Science


Psychological Science (MS)

First Advisor/Chairperson

Dr. Adam Prus


Major Depressive Disorder (MDD) is the leading cause of disability worldwide. The prevalence of MDD is 12% in men and 20% in women. Antidepressant drugs are the first line of treatment in Major Depressive Disorder and other mood disorders, particularly selective-serotonin reuptake inhibitors. Affective blunting is a potential side effect of chronic SSRI treatment, which can be defined as a diminished response to pleasurable or unpleasant stimuli, and is indicated as a marked indifference towards engagement in activities. The present study looked to examine the effects of chornic fluoxetine (0.16g/L) administration on pre-test and post-test performance of a light aversion task and a sucrose preference test. The light aversion task presents subjects with a bright aversive light which can be terminated by a head-entry into an apparatus, and are measured as escape responses. The sucrose preference test measures amount of sucrose consumption pre and post treatment. A significance was found in the male fluoxetine group, who performed significantly less escape responses than before treatment. There were no significant differences between treatment groups found in female operant responding, nor in the sucrose preference test. This study is the first known attempt to exhibit affective blunting in an animal model.

Access Type

Open Access