This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Basics of Psychiatry, Subject name: Psychiatry
Immediate memory is tested by:- 
Select and explain. 
A. Digit span forward, B. Digit span backward, C. Subtraction test 20-1, D. Subtraction test 100-7
A: Digit span forward
Answer: A: Digit span forward 
Explanation: Immediate memory is usually tested by digit repetition test. Usually digit repetition forward is used however digit repetition backward is also used by some examiners, though its not the preferred technique. (Reference Strub and Black's The mental status examination in neurology) Digital repetition forward upto score of 5 and Digital repitition backward upto 4 is considered normal.