Sensory memory is the immediate, very brief recording of sensory information in the memory system. It holds a literal copy of the input for a fraction of a second to a few seconds, depending on the modality.

Iconic memory stores visual information for roughly a quarter of a second; echoic memory stores auditory information for three or four seconds. George Sperling’s partial-report experiments demonstrated that the capacity of iconic memory is larger than what people can report before the trace fades. Sensory memory allows the system to extract relevant features and to integrate information across brief interruptions, such as eye blinks or gaps in sound.

Only a fraction of the sensory memory trace is selected by attention for further processing in working memory. The rest decays and is lost. Sensory memory is modality-specific and pre-categorical; it has not yet been interpreted as meaningful objects or events.

The lingering afterimage of a sparkler or the fading echo of a sentence just heard are everyday reminders of sensory memory.