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# Information processing and the discovery of iconic memory

## Problem

In 1960, Dr. George Sperling asked participants to recall a 4x3 group of letters flashed on a screen for less than a second. When instructed to recall as many letters as possible, most participants could only name the first four or five letters.
Dr. Sperling then asked another group to name only one of the rows. After they saw the image flash, he would randomly sound one of three tones. Sounding a high-frequency tone indicated that the participant should give the first line of letters; a medium-frequency tone indicated the middle row; and a low-frequency tone asked for the last row. If the tone was broadcast immediately after the image was flashed, the majority of subjects recalled all four letters. This marked the discovery of iconic memory, the visual form of sensory memory. Audible sensory memory (also known as echoic memory) lasts for several seconds.
Figure 1. Experimental setup for Dr. Sperling
Sensory memory is constantly processing enormous amounts of information from the world around you. What you pay attention to gets passed into working memory. This stage can be described in three major sections – the visuospatial sketchpad, the phonological loop, and the central executive. The sketchpad stores visual information, like a photograph, while the loop deals with words and numbers. The job of coordinating the two falls to the central executive – connecting an address you hear with a map that you see, for example.
Why did Dr. Sperling use a tone to indicate the line of the row he wanted participants to recite?