Sensory memory is the first recorded memory. It only last for a short peroid of time demonstrated by George Sperling's experiment (1960). In this experiment Sperling would flash a group of nine letters to a subject for 1/20th a second. As soon as the letters disappeared a high, medium, or low tone would sound indicating whether the top, middle, or bottom row should be spoken. In his conclusions, almost every letter was correct. Sperling found with this experiment that there were two types of sensory memory.

Iconic memory is the first type of sensory memory. It deals with the sense of sight. It states that anyone's eyes can remember something in great detail, but only for less than a second.

Echoic memory is the second type of sensory memory. It deals witht the sense of sound. It states that a sound can be remembered for about three or four seconds.

References
(Myers, 2007)