Cognitive Processes PSY 334 Chapter 6 – Human Memory: Encoding and Storage July 31, 2003

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.

Working Memory Baddeley – in working memory speed of rehearsal determines memory span. Articulatory loop – stores whatever can be processed in a given amount of time. Word length effect: 4.5 one-syllable words remembered compared to 2.6 long ones. 1.5 to 2 seconds material can be kept. Visuospatial sketchpad – rehearses images. Central executive – controls other systems.

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.

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.

Factors Influencing Memory Study alone does not improve memory – what matters is how studying is done. Shallow study results in little improvement. Semantic associates (tulip-flower) better remembered than rhymes (tower-flower), 81% vs 70%. Better retention occurs for more meaningful elaboration.

Elaborative Processing Elaboration – embellishing an item with additional information. Anderson & Bower – subjects added details to simple sentences: 57% recall without elaboration 72% recall with made-up details added Self-generated elaborations are better than experimenter-generated ones.

Self-Generated Elaborations Stein & Bransford – subjects were given 10 sentences. Four conditions: Just the sentences alone – 4.2 adjectives Subject generates an elaboration – 5.8 Experimenter-generated imprecise elaboration – 2.2 Experimenter-generated precise elaboration – 7.8 Precision of detail (constraint) matters, not who generates the elaboration.

Advance Organizers PQ4R method – use questions to guide reading. 64% correct, compared to 57% (controls) 76% of relevant questions correct, 52% of non-relevant. These study techniques work because they encourage elaboration. Question making and question answering both improve memory for text (reviewing is better than seeing the questions first).

Meaningful Elaboration Elaboration need not be meaningful – other sorts of elaboration also work. Kolers compared memory for right-side-up sentences with upside-down. Extra processing needed to read upside down may enhance memory. Slamecka & Graf – compared generation of synonyms and rhymes. Both improved memory, but synonyms did more.

Incidental Learning It does not matter whether people intend to learn something or not. What matters is how material is processed. Orienting tasks: Count whether work has e or g. Rate the pleasantness of words. Half of subjects told they would be asked to remember words later, half not told. No advantage to knowing ahead of time.

Flashbulb Memories Self-reference effect -- people have better memory for events that are important to them and close friends. Flashbulb memories – recall of traumatic events long after the fact. Seem vivid but can be very inaccurate. Thatcher’s resignation: 60% memory for UK subjects, 20% non-UK

Neural Correlates of Encoding Better memory occurs for items with stronger brain processing at the time of study: Words evoking higher ERP signals are better remembered later. Greater frontal activation with deeper processing of verbal information. Greater activation of hippocampus with better long-term memory.