Memory

Psy315 - Class 12, Part 1

(This page last updated 12 October, 2006.)

Much of research in memory has been devoted to determining whether there is more than one type of memory, and if so, where the boundaries are between different memory systems.

William James (1842-1910)

• Psychologist and Philosopher at Harvard
• Proposed that short-term memory was separate from long-term memory

The distinction between short-term and long-term memory continues to this day.

• Short-Term, or Working Memory
  • Currently active
  • Very limited in capacity
  • Maybe around 7 items, maybe as few as 4
  • Old info is easily lost as new info is introduced.
• Long Term Memory
  • Enormous capacity
  • Info can remain even if unused for decades.
  • When info is recalled, it is loaded into Working Memory

The chances of information being recorded in long-term memory can be increased with rehearsal.

• By repeating information over and over, you can keep it in Working Memory for longer.
• The longer it is in Working Memory, the more likely it is to make it into Long Term Memory.

Primacy and Recency Effects

• Recency Effect
  • Could reflect info that is still in Working Memory.
  • Recency effect can be weakened by an intervening task.
• Primacy Effect
  • Material at beginning can be rehearsed more than the later material, so it becomes stronger in Long Term Memory.
  • If material is presented more slowly, performance is better for all except the final items.
    • The slow presentation allows more time for rehearsal.
    • The rehearsal doesn't matter much for the final words, which can remain in Working Memory.
• The intervening task and the slower presentation have very different effects on memory.
  • Performance for the final words is affected by different factors than performance for all the other words.
  • This pattern suggests that two different memory systems are used: Working Memory and Long Term Memory.

The Modal Model of Memory

• Explains primacy.
• Explains recency.
• Explains why interference task interferes with recency but not primacy.
• Explains how rehearsal improves memory.

The Modal Model does not explain long-term recency.

• Example: memory for U.S. presidents
  • Good memory for the first few presidents.
  • Good memory for the most recent presidents.
  • Good memory for a few other very distinctive presidents.
• Can explain long-term recency with two assumptions.
  • More distinctive items are remembered more readily.
  • Putting items at the end of the list makes them more distinctive.

Two different factors contribute to the recency effect.

• Working Memory
• Distinctiveness

See the extensive discussion of primacy, recency, and the Modal Model in Chapter 5 of the textbook.

next topic: Working Memory
 
Psych 315: Cognitive Psychology Kyle Cave Psychology Dept. U. Mass.