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).
The addition of a control group that does not use the drink additive would help Dr. Bloedorn address which of the following threats to internal validity?
A)History
B)Demand characteristics
C)Instrumentation
D)Placebo effects

Question

Quizplus · Accepted Answer

Adding a control group that does not use the drink additive would help Dr. Bloedorn address the threat of history, which refers to any external event that may have influenced the outcome of the study (e.g. a new policy or event that affected the behavior of the participants). By having a control group, Dr. Bloedorn can see if any changes in calorie consumption during dinner are due to the additive or other external factors. The other options (B, C, D) are not applicable to the specific scenario described in the question.

Dr Bloedorn Is a Health Psychologist Who Researches Nutrition