Memory Span


Introduction

Cognitive psychologists argue that short term memory can hold a limited amount of information for a short period of time; the memory span paradigm was devised to explore this issue.


Summary

Short term memory can hold a limited amount of information. The results of a typical memory span experiment reveal that a 'typical' short term memory can hold about 6 items (5 to 9 is the normal range). The results also suggest that short term memory is verbal in nature; when the items are letters that sound alike (sound alike condition) than when the letters don't sound alike (random letter condition) because when letters sound alike they are confused in memory. Other evidence that short term memory is verbal comes from the fact that memory span is smaller for longer words than for shorter words. This length of item effect has led researchers to hypothesize that information in short term memory is stored in 'chunks' and that syllables each represent one 'chunk' of information


Because longer words have more syllables, and more chunks, fewer can be retained. The following example should demonstrate how chunk can help short term memory.


Review Questions

Question: Suppose you were shown the following list of 14 letters


     RCM-PNH-LAS-APG-PA


Study for a minute or so and then look away and try to recall them, how did you do?


Now consider the same group listed like this


     RCMP-NHL-ASAP-GPA


Study for a minute and then try to recall. Did you see a difference in ease of recall? Explain.


Answer: If your recall was better for the second list it was likely because in the first example there were 14 chunks of information to recall but in the second there were only 4, even though the number of letters was the same.


Question: If you were given a list of two-digit numbers to remember (like 15, 22, 18, 78, 99) how would recall compare to recall a task with single digit numbers?


Answer: recall would be worse because each double digit number contains several syllables whereas on the digit ‘7’ contains more than one syllable. It will be more difficult to rehearse words with more syllables and recall will not be as high.