What is the difference between forward and backward digit span in terms of cognitive demand?

• A. Backward span requires manipulation, engaging the central executive
• B. Forward span requires manipulation; backward span measures storage
• C. Both measure storage, no manipulation
• D. Backward span measures long-term memory

Answer: (D)

The key distinction is how much mental manipulation the task requires, which taps the central executive in the Working Memory Model. Forward digit span mainly tests short-term verbal storage in the phonological loop—you repeat the digits in the same order with little extra processing. Backward digit span, however, requires you to hold the sequence and actively reverse it in your mind, a processing step that engages the central executive to update and reorganize the information. Because of that added manipulation, backward span is more cognitively demanding than forward. Long-term memory isn’t the main factor here—these tasks measure short-term working memory, not storing and retrieving information from long-term memory.