
 
 The present experiment was based on a study done by Sperling in the 1960's. 
 Sperling (1960) used the partial report procedure in order to explore the
 iconic memory (visual sensory memory). Previous research findings tended to 
 underestimate the size of the iconic memory store, due to interference and 
 decay. By interference it is meant that response is interfering with the 
 memory trace, and by decay it is meant that time needed for report to be made 
 is longer than the duration of the memory trace. 

 
 Sperling found the way to overcome these problems by asking subjects to 
 report only some of the presented stimuli. This was done by presenting 
 stimuli in an array consisting of 3 rows with 4 letters each. 
 Soon after the array was removed from the screen, a tone was presented. 
 Tone was used as a cue to which row was to be reported. If the high pitch 
 tone was presented subjects were supposed to report only top row letters, 
 the medium pitch tone signaled the middle row, and the low pitch tone was 
 a signal for the bottom row.

 
 
 
 
 
 
 
 Another advantage of such a procedure was that by manipulating the onset 
 of the tone one was able to establish the rate of decay of the iconic memory. 
 Sperling's original results showed that subjects were able to report as many 
 as 75% of the letters if the cue was presented immediately after the 
 stimulus array. As subjects were not able to guess which row was selected 
 for recall in a particular trial Sperling reasoned that the size of iconic 
 memory is at least 9 letters (3 * .75 * 4). Prolonging the delay of the 
 recall signal resulted in rapid decay of information. When delay was one 
 second recall accuracy was no better than what was obtained in the "whole 
 report" experiments.
 
 
 
 In the present experiment 12 letter arrays (3*4) were used. On the
 basis of the delay of the recall cue there were 5 experimental conditions: 0 ms, 100 ms,
 250 ms, 500 ms, and 750 ms. Results are saved in the SPSS ready format
 (see readme.txt file for details).

 The following frequency tones were used for
 top, middle and bottom row recall cues: 900Hz., 200Hz, and 50Hz. 
 

 Procedure:
 Present an array for 100 ms.
 Pause for 0, 100, 250, 500, or 750 ms., depending on a condition
 Sound a recall cue (50, 200, or 900 Hz. sound depending on a condition)
 
