If you have a ceiling effect on your DV, it means: Question 25 options:
a) Your test was too easy - most people scored well, which threatens your internal validity.
b) You had a weak manipulation and should have done a manipulation check.
c) You exhibited demand characteristics and should have used a placebo condition, automation, or a double-blind study.
d) Your test was too hard - most people scored poorly, which threatens your internal validity.
e) All of the above.