dr. timothy bender psychology department missouri state university 901 s. national avenue

Sperling (1960)

Estimating the Duration of Iconic Memory: Delayed cues

in the partial report methodDr. Timothy Bender

Psychology DepartmentMissouri State University901 S. National AvenueSpringfield, MO 65897

Duration

In the fourth experiment in Sperling’s (1960) classic study of the characteristics of the iconic memory (visual sensory memory), he explored how long the memory trace might last. He used the Partial Report Method with an added variable – He manipulated the timing of the cue.

DurationIn the Partial Report Technique participants see an array of letters with two or more rows, but they are signaled as to which row of the array to report. Usually, the signal is a tone that occurs at the offset of the array.

DurationIn his fourth experiment, Sperling manipulated the timing of the cue. The timing levels included included• 100 milliseconds before the onset• With the offset• 150 milliseconds after the offset• 300 milliseconds after the offset• 500 milliseconds after the offset

DurationSperling used both 2x3 arrays and 2x4 arrays. He also presented each different timing condition in a block of trials. Furthermore, the participants were exposed to two practice trials before each set of arrays. Therefore, the participants became used to each timing.

DurationAs you might expect, the best performances were when the cue was just prior to the appearance of the array. The participants performed more poorly as the cued was delayed.

DurationWe will do something similar. You will see several slides with auditory cues occurring at different times relative to the presence of the array. Like Sperling’s study, in this demo you will get each timing in blocks. However, the array will be a 3x4 array and the sequence of the target rows will be random.

DurationIn the first block, you will see 6 different 3x4 arrays of letters. Approximately 100 milliseconds before the array appears, you will hear a tone. A high tone means you should record the top row. A medium tone means you should record the middle row. And a low tone means you should record the bottom row.

Duration

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.

DurationProcedure• After the next slide, you will see 6 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. • The tone will occur about 100 milliseconds before the array appears.

DurationYour 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

Record your response.

DurationScoring• Give yourself one point for each letter in the correct location for all 6 stimuli.• Multiply that number by 3, because there were 3 rows possible.• Divide that number by 6 to get your mean score.

1 GSBQ 4 VSNF

2 SKBS 5 RPFD

3 CBFW 6 PVXR

DurationIn the second set, you will see 6 different 3x4 arrays of letters. The tone will occur just as the array disappears from the screen. A high tone means you should record the top row. A medium tone means you should record the middle row. And a low tone means you should record the bottom row.

DurationProcedure• After the next slide, you will see 6 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.


1 DNWF 4 KHXR

2 BFJZ 5 MYJX

3 FXCJ 6 NZBF

DurationIn the third set, you will see 6 different 3x4 arrays of letters. The tone will occur approximately 100 milliseconds after the array disappears from the screen. A high tone means you should record the top row. A medium tone means you should record the middle row. And a low tone means you should record the bottom row.


1 GSBP 4 LXGC

2 QTDV 5 JWGB

3 LYBG 6 PZQD

DurationIn the fourth set, you will see 6 different 3x4 arrays of letters. The tone will occur approximately 300 milliseconds after the array disappears from the screen. A high tone means you should record the top row. A medium tone means you should record the middle row. And a low tone means you should record the bottom row.


1 NWJF 4 ZTFV

2 JVHP 5 NZJG

3 WSVP 6 QCMF

Duration

In class, compare your class scores for the Pre, Offset, 100 delay, and 300 delay tasks. If you performed similarly to Sperling’s participants, you performed best when the tone occurred just prior to the array and worst with the 300 millisecond delay.

Duration

The following tables shows how Sperling’s participants performed with the 3x3 and 3x4 arrays. You should note two things:

1 The performance became worse as the delay increased.

2 The performance in the 1 second delay condition was close to what Sperling found in his first experiment using the Whole Report Method.

Based on these types of results, Sperling felt that the iconic memory trace was unavailable after a second. Other researchers have since suggested that 250 to 300 milliseconds is a good estimate of the duration of the iconic memory trace.

References

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

dr. timothy bender psychology department missouri state university 901 s. national avenue

Documents

high tone

low tone

medium tone

3x4 array of letters

middle row

timing levels

different timing condition

offset durationsperling