Cognitive Processes PSY 334 Chapter 6 – Cont. Chapter 7 – Human Memory: Retention and Retrieval August 5, 2003

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 word 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.

Two Ways of Testing Memory  Recall Essay exams  Recognition Multiple-choice exams  Snow White’s dwarfs demo

What is Forgetting?  Do memories still exist in mind when we cannot remember? Penfield – stimulated areas of the brain and got reports of recall from childhood. No way to check the accuracy of reports.  Nelson – some savings are evident even when subjects cannot remember items: Savings found with both recall and recognition tests.

The Retention Function  Wickelgren – studied the retention function: Performance is a function of delay. Log (d’) = A – b log T Where: T is delay, d’ is performance (memory strength).  Power law of forgetting -- power function becomes linear when plotted on log-log scales.

Rate of Forgetting  Retention function shows diminishing loss (forgetting) with delay.  Theory of short-term memory predicts sharp drop-off followed by stable memory. Since all retention functions are like this, there is nothing special about short-term memory compared to long-term memory. Practice postpones the point of decay.

Long-Term Retention  Bahrick – studied retention of English- Spanish vocabulary over 50 years. Substantial practice effect. Slow decline after 3 yrs. Drop-off at end due to physical aging.  Barnes – decrease in long-term potentiation with delay. Mirrors retention function. Decay theory of forgetting – LTP changes.

Interference  Interference paradigm – two groups defined: Experimental group – learns new associations for previously learned list Control group – learns entirely new list  Typically the experimental group does worse after a delay.  Does this mean that it is difficult to maintain multiple associations?

Fan Effect  There is a limit to how much activation can spread within a network: The more associations, the less activation can spread to any particular structure.  Anderson – fan effect: Recognition time increases with the number of facts about a person and a location.

Preexperimental Memories  Does knowledge brought into an experiment interfere with new learning?  Lewis & Anderson – facts about Napoleon: Fantasy facts – learned during experiment True facts – from the real world False facts – not studied in experiment and not true in the real world  Fan effect occurs with all three fact types

Interference vs Decay  Less forgetting during sleep than when awake. Occurs because material is retained better when learned at night. Night is period of highest arousal.  Forgetting functions may reflect interference from unknown sources.  Decay theories do not specify any mechanism for decay.

Effects of Redundancy  Interference occurs only when learning multiple memories that have no relationship to each other.  Bradshaw & Anderson – compared relevant and irrelevant fact learning: Irrelevant facts interfere. Relevant facts aid memory compared to single fact learning.

Retrieval and Inference  Much of memory is inference at the time of recall – not actual recall of facts.  Bransford et al. -- inference can lead to incorrect recall: Turtles resting on or beneath log. Subjects were most confused by sentences whose meaning was implied by the studied sentences.

Inference-Based Intrusions  Sulin & Dooling – subjects add details not present during learning: Carol Harris vs Helen Keller “She was deaf, dumb and blind.” 5% Carol Harris but 50% Helen Keller subjects falsely recognized the sentence.  Inferences are made at test-time. More inferential errors occur with delay.

Plausible Retrieval  Reder – much of recall is plausible inference not actual recall. Darth Vader inferred to be evil, not remembered to be evil. Heir to hamburger chain story – subjects asked to recall exact details and make plausible inferences.  After a delay, plausible inference is faster and does not decay as much as exact memory, with no fan effect.

Inference and Elaboration  Elaboration leads to more inferences. Information added as a “theme” to a story results in better recall of studied material and more inferences.  Intruded inferences are not necessarily “errors” but help guide our thinking and behavior.  Listerine court case – false inferences, not just false statements, not permitted.

Memory Errors  When exact memory is needed, inferences and reconstructive processes can be misleading.  Loftus -- additional details and suggestion can change what is recalled.  John Dean’s recall vs what Nixon recorded – gist was right but not details.  False memory syndrome – memories that never happened can be “planted.”