The Atkinson-Shiffrin Model proposes that human memory consists of three stores: sensory memory, short-term memory, and long-term memory. Sensory memory briefly stores sensory information through iconic, echoic, and haptic memory. Short-term memory then stores about 7 chunks of information that can be rehearsed for around 18-20 seconds. Long-term memory permanently stores meaningful information through elaborative rehearsal and associations with existing knowledge.