The spacing effect states that rehearsal is most effective when:

• A. Cramming is best
• B. Spaced rehearsal improves retention
• C. Rehearsal has no effect
• D. Short sessions are always best

Answer: (B)

The main concept tested is the spacing effect in memory: spreading rehearsal over time leads to stronger, longer-lasting retention than cramming everything into one session. When you space out practice, each review happens after some forgetting has begun, which makes retrieval effortful and, in turn, strengthens the memory trace. You also gain the benefit of encountering the material in slightly different contexts and with different retrieval cues, which improves your ability to recall later. This is why distributed practice yields better long-term retention than massed practice. Cramming tends to boost short-term performance but fails to build durable memory. Saying rehearsal has no effect ignores the well-supported finding that repetition enhances memory, and claiming that only short sessions are best misses the critical factor—the gaps between sessions. Short sessions can help, but what matters most is spacing them out to allow consolidation and repeated retrieval over time.