Iconic Memory Dr. Paula Waddill Murray State University Adapted from: Timothy Bender, Missouri State University; http://courses.missouristate.edu/tab293f/mem/exe/oldiconlab.exehttp://courses.missouristate.edu/tab293f/mem/exe/oldiconlab.exe Note: You will need a computer with sound for this demonstration.
In the first part of this demonstration, you’ll experience the whole report procedure used to study iconic memory (Sperling, 1960, Exp. 1). You’ll see a 4 x 3 array of letters appear briefly on the screen. Then you will have to recall the whole array. Full Report Procedure
To give you an idea of how fast the arrays will be presented, let’s look at some examples. The first sample array will be displayed for 1000 msec (1 sec). The second sample will be displayed for 500 msec. The last sample will be displayed for 100 msec (the speed used in this demonstration). When you’re ready to see the examples, click the Start Samples button. Start Samples
Now you are ready for the memory trials. All the arrays will be presented for approximately 100 msec (although the actual speed of the display will depend upon the computer you are using). Before you begin, take out a sheet of paper and number it from 1 to 10. Leave enough space between each number to write down a complete 4 x 3 array of letters.
Before each trial, you will see a fixation cross (+) appear on the screen. Keep your eyes focused on the location of the cross when the 4 x 3 array flashes on the screen. It’s very important that your eyes are looking at the center of the screen when the array flashes. After the array disappears, you are to write down the entire array of 12 letters (3 rows of 4 letters each). Even if you cannot specifically remember a letter, you must write a letter in each position in the array. The same letter may appear more than once in an array. After you’ve recalled the array, click the mouse to advance to the next trial. When you are ready to start the memory trials, click the Start Trials button. Start Trials
Now, it’s time to score your arrays. Give yourself 1 point for each letter you recalled in the correct position in an array. Add up all your points, then divide by 10 to get your mean score for the full report condition. Array 1 RMXP WBGK TNXQ Array 2 YMPB DSBJ KGRW Array 3 MNTL GBCF STSR Array 4 XTBS FRWM PBKZ Array 5 DGKP WDRN AZCT Array 6 HLNQ MGHL PXEH Array 7 MJGE RYPN VKRA Array 8 NVLP SGBY KSJZ Array 9 RJFL SBHM XWKC Array 10 YVBW ZGNT MLDF
Next, you will participate in the partial report procedure that was developed by Sperling (1960, Exp. 3). With that procedure, Sperling’s subjects did not have to recall the entire array. Instead, after the array disappeared, they heard a tone that signaled which row of the array they were to recall: top (high tone), middle (medium tone), or bottom (low tone). The tones were randomly ordered so the subjects could not predict which row they would have to remember. Partial Report Procedure
In this part of the demonstration, you will again see 4 x 3 arrays flashed on the screen for 100 msec. As the array disappears, you will hear a tone that signals which row you are to recall. A high pitched tone means you are to write down the 4 letters in the top row; a medium pitched tone means to write the 4 letters in the middle row; a low pitched tone means write the 4 letters in the bottom row. You must write 4 letters for the indicated row even if you aren’t sure that all of them are correct. The same letter may appear more than once in an array and in a row.
First, listen to the tones. Click the sound icon next to each button to hear the tone. Listen to each tone at least 3 or 4 times in different orders (and with your eyes closed) until you can clearly tell the difference. It is important that you recognize and remember which tone signals which row of the array. When you are completely familiar with the tones and can remember which pitch signals which row, click the Advance button. High pitch (Top Row) Medium pitch (Middle Row) Low pitch (Bottom Row) Advance to Next Slide
Before you begin, number a sheet of paper from 1 to 10. A fixation cross will appear before each array. Keep your eyes focused on the location of the cross when the array appears. It is very important that you keep your eyes focused on the middle of the screen when the array is presented. Do not try to predict which row you’ll be asked to recall. As the array disappears, you’ll hear one of the tones. When the tone sounds, write down the 4 letters from the row associated with the tone (top row for high tone, middle for medium tone, bottom for low tone). You must write 4 letters. After you’ve recalled the row, click the mouse to advance to the next trial. When you are ready to start the memory trials, click the Start Trials button. Start Trials
Now, it’s time to score your recall. Give yourself 1 point for each letter you recalled in the correct position in the row. Add up all your points and divide the total by 10; then multiply that result by 3 to get your mean score for the partial report condition. Array 1 WRTZ Array 2 DPCR Array 3 TRXT Array 4 MRLS Array 5 TRDR Array 6 BTQE Array 7 RYSA Array 8 CVNL Array 9 PDXM Array 10 EHMQ
With the whole report procedure, Sperling (1960, Exp. 1) found that his subjects had a mean recall score of 4.3 letters. He hypothesized that the whole report procedure led to an underestimate of the amount of information that could be held in iconic memory because the iconic image fades before subjects can write down all the letters that were originally held in it. Discussion
With the partial report procedure, Sperling (1960, Exp. 3) proposed that if a person can remember X amount of letters from a randomly selected row, then that person must have had access to X*r letters in iconic memory to begin with (where r = the number of rows in the array). He found that with the partial report procedure, his subjects had a mean score of 9.1 letters. He proposed that the reason their score was not perfect was that the iconic image was fading faster even than the time it took to write down just the letters in a single row. Discussion cont’d.
If your scores are quite different from the average for Sperling’s subjects, don’t worry. He gave his participants extensive training prior to conducting the memory trials and he also used many more than 10 trials per condition. Also, he was able to control subjects’ distance from the screen, size of the screen, and display angle, which cannot be done with this demonstration where you are viewing it on your own computer in your own environment. Furthermore, Sperling displayed his arrays for 50 msec, but because of the limitations of the presentation software for this demonstration, the arrays here were displayed for 100 msec.
Sperling, G. (1960). The information available in brief visual presentations. Psychological Monographs: General and Applied, 74, 1-29. References