Cognitive Processes PSY 334 Chapter 6 – Human Memory: Encoding and Storage May 7, 2003

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.

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)

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.

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.

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.

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.

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.