For the following scenarios, please use the following list of threats to internal validity included in chapter 11: Maturation, History, Regression to the mean, Attrition, Testing, Instrumentation, Observer bias, Demand Characteristic, and Placebo Effect. To assess the effects of delaying negative reinforcement, the following experiment was conducted. Subjects watched a confederate performing a task under coercive conditions. The confederate winced in pain in apparent reaction to continuous electric shock. Periodically, a light signaled the subjects to press a button, after which they were required to evaluate the confederate's task performance. The button press also appeared to relieve the confederate's suffering for 10 seconds. For Group A, the button press immediately stopped the suffering; for Group B, the button press stopped the suffering after a three second delay. The dependent measure was reaction time from the onset of the signaling light to the button press. University student volunteers were assigned to one of these two groups on the basis of a coin flip. About 25% of the subjects in each group discontinued their participation midway through the experiment, citing ethical concerns. Response latency for remaining Group A subjects was significantly faster than for remaining Group B subjects. We can conclude that delaying negative reinforcement prolonged response latency.