Dr Bloedorn Is a Health Psychologist Who Researches Nutrition

Multiple Choice

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