Short-term memory (STM) is the memory system that holds a small amount of information in conscious awareness for a brief period, typically 20–30 seconds and about seven items, plus or minus two. It is also called working memory in more recent models.

Information enters STM from sensory memory or from long-term memory. Without rehearsal, it decays rapidly; with rehearsal, it can be maintained and possibly transferred to long-term memory. Chunking—grouping items into meaningful units—increases effective capacity. The digit span task is a classic measure of STM capacity.

Key features

• Capacity: about 7 ± 2 items
• Duration: about 20–30 seconds without rehearsal
• Rehearsal maintains and transfers information
• Chunking expands effective capacity