Online

Schoenberg, Hannah

Psychology

2018

MA

Experiment 1 examined the role of sex in habit formation in which intact male and female rats received identical training, devaluation, and testing in two separate within-sex experiments. After 240 reinforcer exposures females exhibited habitual behavior whereas males remained goal-directed. In Experiment 2, female rats were ovariectomized (OVX) and half were given cyclic estrogen replacement. All animals received either pre-exposure to methamphetamine (METH) or vehicle. Following exposure to 120 reinforcers, a level of training that had previously been shown to be subthreshold to habit formation in males, all female groups demonstrated goal-directed responding at test, revealing a lack of effect of hormone replacement or drug pre-treatment on habit formation in OVX females at this level of reinforcer exposure. Experiment 3 aimed to determine the degree of nose-poke training that would be sub-threshold to habit formation in intact females, and two groups were given different amounts of training. Both groups exhibited habitual responding, indicating that habit threshold in females is lower than hypothesized. Overall, these experiments suggest that females shift into habitual behavior earlier in training than males, and further experiments need to be conducted to determine how factors such as hormone milieu and psychostimulant exposure influence this progression.