Human Memory
Lesson 8
Human Memory Factors Affecting Capacity in STM Produced by
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Factors Affecting Capacity in STM Influence of long-term memory: • There are some difficulties in using the digit span to measure STM capacity. One problem is you cannot exclude long-term memory. • For example, Bower & Weinzenz (1969) found that digit strings that are repeated within a series of immediate memory span trials become easier for participants to recall over a period. This indicates that information stored in LTM is helping to increases the STM capacity temporarily.
Reading aloud: • If participants read the digits aloud before attempting to recall them, performance is better than when they simply read them silently to themselves. Rhythmic grouping : • Performance also improves if the numbers are grouped together rhythmically. This is probably why we tend to divide telephone numbers into rhythmic groups rather than reciting the whole string of numbers in a monotone.
Pronunciation time: • Some researchers have found that pronunciation time may be a more important indicator of STM capacity than Miller’s digit span. • Schweickert & Boruff (1986) tested immediate memory span for a number of different types of stimulus, such as letters, colour, shapes, and nonsense words. • They found that people repeatedly remembered as many items as they were able to pronounce in approximately 1.5 to 2 seconds.
Supporting Evidence for Pronunciation Time Naveh –Benjamin & Aryes (1986) • They tested immediate memory span for speakers of various world languages. They found for example that the digit span for native English speakers is considerably greater than that of Arabic speakers. • The only explanation for this finding is that Arabic numbers take longer to pronounce than English numbers. These results confirmed earlier findings in a classic study by Baddeley at al. (1975).