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 –  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.