Final answer:
Iconic and echoic memory belongs to the sensory memory stage in the Atkinson-Shiffrin model, serving as the initial fleeting storage systems for visual and auditory information, respectively.
Step-by-step explanation:
Iconic memory and echoic memory occur at the sensory memory stage, which is the first stage in Atkinson-Shiffrin's three memory stages. Sensory memory is where brief sensory events are stored, such as sights and sounds, for up to a couple of seconds before they are either discarded or move on to the next stage, which is short-term memory, if they are deemed valuable. Iconic memory refers to the visual sensory memory, while echoic memory refers to the auditory sensory memory.