Transcript Jul29
Cognitive Processes PSY 334 Chapter 5 (Cont.) Chapter 6 – Human Memory: Encoding and Storage July 29, 2003 Psychological Reality of Schemas Brewer & Treyens – subjects left in a room for 35 sec, then asked to list what they saw there: Good recall for items in schema False recall for items typically in schema but missing from this room. 29/30 recalled chair, desk; 8 recalled skull 9 recalled books when there were none Degrees of Category Membership Members of categories can vary depending on whether their features satisfy schema constraints: Gradation from least typical to most typical. Rosch – rated typicality of birds from 1-7: Robin = 1.1 Chicken = 3.8. Faster judgments of pictures of typical items, higher sentence-frame ratings. Disagreements at Category Boundaries McCloskey & Glucksberg – subjects disagree about whether atypical items belong in a category: 30/30 apple is a fruit, chicken is not a fruit 16/30 pumpkin is a fruit Subjects change their minds when tested later. Labov – boundaries for cups and bowls change with context. Event Concepts (Scripts) Schank & Abelson – stereotypic sequences of actions called scripts. Bower, Black & Turner – script for going to a restaurant. Scripts affect memory for stories: Story elements included in script well remembered, atypical elements not recalled, false recognition of script items. Items out of order put back in typical order. Two Theories What happens mentally when we categorize? Two theories are being debated. Abstraction theory -- we abstract and store the general properties of instances. Prototype theory. Instance theory -- we store the multiple instances themselves and then compare average distances among them. Neural Nets for Learning Schemas Gluck & Bower – designed a neural net that abstracts central tendencies without storing instances. Patients with four symptoms classified into two hypothetical diseases. One disease 3 times more frequent than the other. Error correction changes the strength of associations in the network (delta rule). Model predicted subject decisions well. Evidence From Neuroscience People with temporal lobe deficits selectively impaired in recognizing natural categories but not artifacts (tools) People with frontoparietal lesions unaffected for biological categories but cannot recognize artifacts (tools). Artifacts may be organized by what we do with them whereas biological categories are identified by shape. Bartlett’s War of the Ghosts Demo Cognitive Processes PSY 334 Chapter 6 – Human Memory: Encoding and Storage July 29, 2003 Ebbinghaus First rigorous investigation of human memory – 1885. Taught himself nonsense syllables DAX, BUP, LOC Savings – the amount of time needed to relearn a list after it has already been learned and forgotten. Forgetting function – most forgetting takes place right away. Memory Models Atkinson & Shiffrin – proposed a three- stage model including: Sensory store – if attended goes to STM Short-term memory (STM) – if rehearsed goes to LTM Long-term memory (LTM) No longer the current view of memory. Still presented in some books. 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. 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.