Dr. Bloedorn is a health psychologist who researches nutrition. She is curious as to whether a new drink additive will help people consume fewer calories during a meal. The drink additive is a white, odorless, tasteless powder that a person can add to any drink. She collects a random sample of 63 overweight students on campus and measures the calories they eat during lunch using a bomb calorimeter. She then gives this additive to the same 63 participants to use at dinner and measures how many calories they eat (again using the bomb calorimeter).
Which of the following threats to internal validity will Dr. Bloedorn NOT be worried about?
A)Testing effect
B)Attrition
C)Demand characteristics
D)Placebo effects

Question

Quizplus · Accepted Answer

Dr. Bloedorn will not be worried about attrition because there is no indication that participants dropped out of the study before it was completed.

She may be concerned about the testing effect because participants may become more familiar with the procedure of measuring calorie intake as the study progresses. She may also be concerned about demand characteristics because participants may alter their behavior based on their perception of what is expected of them. Finally, she may be concerned about placebo effects if participants believe that the additive has a certain effect on their appetite, even if it does not actually work.

Dr Bloedorn Is a Health Psychologist Who Researches Nutrition