1. Cognitive Processes PSY 334
Chapter 6 – Human Memory: Encoding and Storage

2. Criticisms of STM
Rate of forgetting seemed to be quicker than Ebbinghaus’s data, but is not really.
Amount of rehearsal appeared to be related to transfer to long-term memory.
Later it was found that the kind of rehearsal matters, not the amount.
Passive rehearsal does little to achieve long-term memory.
Information may go directly to LTM.

3. Depth of Processing
Craik & Lockhart – proposed that it is not how long material is rehearsed but the depth of processing that matters.
Levels of processing demo.

4. Working Memory
Baddeley – in working memory speed of rehearsal determines memory span. Articulatory loop – stores auditory input (speech) for 1.5 to 2 seconds.
Visuopatial sketchpad – rehearses images.
Central executive – controls other systems.

5. Articulatory Loop
The word-length effect provides evidence of the existence of the articulatory (phonological) loop.
When a list of words is read, the number recalled depends on how long the words are:
Wit, sum, harm, bay top = 4.5 words
University, opportunity, aluminum, constitutional, auditorium = 2.6 words

6. Delayed Matching Task
Delayed Matching to Sample – monkey must recall where food was placed.
Monkeys with lesion to frontal cortex cannot remember food location.
Human infants can’t do it until 1 year old.
Regions of frontal cortex fire only during the delay – keeping location in mind.
Different prefrontal regions are used to remember different kinds of information.

7. Activation Activation – how available information is to memory:
Probability of access – how likely you are to remember something.
Rate of access – how fast something can be remembered.
From moment to moment, items differ in their degree of activation in memory.

8. Factors Affecting Activation
How recently we have used the memory:
Loftus – manipulated amount of delay
1.53 sec first time, then 1.21, 1.28, and 1.33 with 3 items intervening.
How much we have practiced the memory – how frequently it is used.
Anderson’s study (sailor is in the park)

9. Spreading Activation
Activation spreads along the paths of a propositional network:
Dog – c Gambler – c
Bone – m bone – m
1.41 sec 1.53 sec
Associative priming – involuntary spread of activation to associated items in memory.

10. Associative Priming
Meyer & Schvaneveldt – spreading activation affects how fast words are read.
Subjects judged whether pairs of related & unrelated items were words.
Ratcliff & McKoon – priming influences word recognition.
Subjects identified words from sentences faster with priming.

11. Practice and Strength
Amount of spreading activation depends on the strength of a memory.
Memory strength increases with practice.
Greater memory strength increases the likelihood of recall.

12. Power Function
Each time we use a memory trace, it gradually becomes a little stronger.
Power law of learning:
T = 1.40 P-0.24
T is recognition time, P is days of practice.
Linear when plotted on log-log scale.

13. Long Term Potentiation (LTP)
Neural changes may occur with practice:
Long-term potentiation (LTP) in hippocampus.
Repeated electrical stimulation of neurons leads to increased sensitivity.
LTP changes are a power function.