The “Reading the Mind in the Eyes Test” (RMET) measures the ability of a person to infer the mental state of another from looking at facial expressions. Researchers Domes et al. (Biological Psychiatry, 2007) conducted a study on the effect of oxytocin (a hormone oft en linked with bonding, trust, and empathy) on people’s performance on the RMET. Thirty healthy male volunteers (ages 21–30 years) were administered oxytocin and a placebo—each as a nasal spray, in a random order and with a week of washout period between the two treatments. Forty-five minutes after administering each treatment, participants were given the RMET. The researchers noted that the average increase in RMET score when on oxytocin compared to when on the placebo was 3 points, with a standard deviation of 7.54 points. The differences in RMET scores were not strongly skewed.
a. Define, in words, the appropriate parameter(s) of interest in the context of the study. Also, state the appropriate symbol(s) to denote the parameter(s).
b. State, using the symbol(s) described in part (a), the appropriate null and alternative hypotheses to test whether the use of oxytocin causes an increase in ability to infer the mental state of others, as measured by the RMET score.

c. State the validity conditions that have to be met to be able to perform a theory-based test to test the hypotheses stated in part (b). Are these conditions met? How are you deciding?

d. Regardless of your answer to part (c), perform a theory-based test to test the hypotheses stated in part (b). Be sure to report a test statistic value and a p-value in your answer.

e. Interpret your p-value in the context of the study.

f. Find a 95% confidence interval for the parameter of interest.

g. Provide a full (four-part) conclusion, including comments on significance, estimation, causation, and generalization.