Dr. Wright sets up a study where participants are given a series of questions. Some questions are easy while other questions are difficult. It is not likely that the participants would be able to answer the difficult questions correctly. Dr. Wright makes it clear that she forgot the answer key to the questions prior to leaving the room of participants unattended. There is a hidden camera in the room to see what the participants do. After Dr. Wright is absent for 10 minutes she returns to the room. Participants then turn in their responses and have their heart rate, perspiration, etc. measured once they leave the testing room. What is one aspect that Dr. Wright is measuring of participants