Sperling (1960) Estimating the Iconic Memory Capacity: Whole report and partial report methods Dr....

Sperling (1960)

Estimating the Iconic Memory Capacity: Whole report and

partial report methods

Dr. Timothy BenderPsychology DepartmentMissouri State University901 S. National AvenueSpringfield, MO 65897

Whole Report MethodSperling (1960) is a classic study of the characteristics of the iconic memory (visual sensory memory). One characteristic of the iconic memory that Sperling explored was its capacity, or how much information was available in a single, brief exposure to a visual stimulus.

Whole Report MethodAt that time, a common method for studying the capacity of the iconic memory was the Whole Report Method. In that method, research participants would be briefly exposed to a visual stimulus, then asked to recall as much of the information as possible.

Whole Report MethodIn Sperling’s research, the participants might see a 2x4 array of letters for 50 milliseconds. They then had to report what letters they saw and in what position.

D J W PB S L M

Whole Report MethodIn order for you to get a feel for what that is like, you will see several slides. Each slide has a 2x4 array of letters. The first array will appear for about one second or 1000 milliseconds.

Operating hint: To move to the next slide after each example, be sure the cursor is near the edge of the screen and is in the shape of an arrow. If the cursor is near the middle of the screen and is the shape of the pointing finger, you will repeat that slide.

Whole Report MethodThe next array will appear for nearly 500 milliseconds.

Whole Report MethodThe next array will appear for nearly 100 milliseconds.

Whole Report MethodSperling’s participants frequently were exposed to an array of letters for only 50 milliseconds!

Whole Report MethodSperling manipulated both the number of letters in the arrays (experiment one) and the duration of the arrays (experiment two). He found that neither the number of letters nor the duration of the display had an appreciable effect on the results. In general, his participants could remember a maximum of between 4 and 5 letters.

Whole Report MethodProcedure:• After the next slide, you will see 10 stimuli. • Each stimulus will start with a slide telling you to get ready. Click on that slide to see the actual stimulus. • Then you will see a + sign in the middle of the screen. Focus on the + sign. • The + sign will remain for about 1 second and will be followed by a 3x4 array of letters. • The array will last for about 70 milliseconds. • Then you will be asked to record the letters from the array.

Whole Report MethodYour job is to write down the letters in their correct positions as quickly as you can. It is important that you write down a letter in every position, even if it feels like a guess. However, do NOT just write down all Xs or something like that. Also, do not focus only on one row. That actually may reduce your overall score.

Prepare for Stimulus 1

Record your response.

Whole Report Method

Scoring Procedure• For each array, give yourself one point for

each letter in the correct position.• Add up your points for all 10 arrays.• Divide that number by 10 to get your mean

number of letters.

Whole Report Method

1 TPBW 2 BFJD 3 KGLC 4 SJKB

QNRL KSWZ RBDX VLNY

GXKJ DHMZ FJNT BFHD

5 CKMF 6 LHNG 7 TLOH 8 DMPL

JTXW QCGV WKRT FVZP

FPSY FJPL DGJK HLRX

9 MPQK 10 VNRJ

SDHR TMQS

CGSM FJLH

Whole Report Method

Sperling (1960) found that his participants could recall between 4 and 5 of the letters. (If you did as well, that is great. If you did not, do not worry about it. His participants also had more practice than you did and completed the task as individuals rather than in a classroom.)

Partial Report Method

One problem with the Whole Report Method is that participants claimed that they saw more letters than they could remember. Apparently, in the time it took to write down the first few letters, the memory for the others was gone. So, Sperling (experiment 3) developed a different technique, called the Partial Report Method.


In the Partial Report Technique, the participants only had to report one row of the stimuli. They were signaled as to which row of the array to report. The signal was a tone that occurred at the offset of the array and the rows were randomly selected. That way, the participants could not predict which row would be required. The number of letters they recalled from the row was then multiplied by the number of rows to get their score.


The logic behind the Partial Report Method is clear. If a participant could recall X letters from any one row, then the participant had available in memory X x Y letters, where Y is the total number of rows.


You will try this in class. You will see 15 different 3x4 arrays of letters. These will be set up like the previous demonstration, with the exception that one of 3 tones will occur at the offset of each array. A high tone means record the top row. A medium tone means record the middle row. A low tone means record the bottom row. The order of the tones has been randomly arranged.


You will need to listen to the tones a few times in order to recognize which one is high, medium, and low.

Move the cursor over this speaker to hear the high tone.

Move the cursor over this speaker to hear the medium tone.

Move the cursor over this speaker to hear the low tone.

Partial Report MethodProcedure• After the next slide, you will see 15 stimuli. • Each stimulus will start with a slide telling you to get ready. Click on that slide to see the actual stimulus. • You will then see a + sign in the middle of the screen. Focus on the + sign. • The + sign will remain for about 1 second and will be followed by a 3x4 array of letters. • The array will last for about 70 milliseconds. • Then you will hear the tone.

Whole Report MethodYour job is to write down the letters in the row that corresponds to the tone. Record the 4 letters in their correct positions as quickly as you can. It is important that you write down a letter in every position, even if it feels like a guess. However, do NOT just write down all Xs or something like that. Also, do not try to predict which row will be cued. That actually may reduce your overall score.

Get Ready for Stimulus 1


Scoring Procedure• We will treat the first 5 as practice trials, so

we will only score the last 10.• For your last 10 trials, give yourself one point

for each letter in the correct position.• Add up your points for those 10 arrays.• Multiply that number by 3 because there

were three possible rows.• Divide that number by 10 to get your mean

number of letters.


6 KSMZ 11 KYLP

7 DQFP 12 KPNC

8 DRCL 13 FTRH

9 GBTQ 14 SFQH

10 KXLC 15 MPTS


Sperling (1960) found that his participants could recall between 9 and 10 of the letters, on the average. (If you did as well, that is great. If you did not, do not worry about it. His participants also had more practice than you did and completed the task as individuals rather than in a classroom.)


Based on Sperling’s research and similar research by others, it was assumed that we can access at least 9 letters in a single brief glance at a visual stimulus. If you break that into separate bits of information, that is about 40 separate bits of information (Sperling, 1960). Notice, that is at least 40 bits of information. We still do not know an upper limit on the capacity of the iconic memory.


The reason we do not know an upper limit on the capacity of the iconic memory is that the memory trace disappears so rapidly. Simply using arrays with more letters does not help because people start to forget the remaining letters in a row while they record the first ones. Imagine trying to remember a row of 5 or 6 letters. There is a strong possibility that by the time you recorded the first 3 or 4 letters, you would lose access to any others.

References

Sperling, G. (1960). The information available in brief visual presentations. Psychological Monographs: General and applied, 74, 1-29.

Sperling (1960) Estimating the Iconic Memory Capacity: Whole report and partial report methods Dr....

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