Purdue PSY 20000 - Memory discrimination (5 pages)

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Memory discrimination



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Memory discrimination

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5
School:
Purdue University
Course:
Psy 20000 - Introduction to Cognitive Psychology
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Prof Greg Francis 1 2 13 Discrimination Memory discrimination PSY 200 Many cognitive tasks require you to discriminate between events stimuli Is this a real smile Greg Francis Is this fruit ripe Is the stapler on the desk Lecture 19 The same kind of discrimination is required for memory How to take a test Purdue University Purdue University Discrimination Discrimination is difficult because memories False memory An example list is smooth bumpy road tough sandpaper jagged ready coarse uneven riders rugged sand boards ground gravel can come from lots of different sources Consider so called False memory studies the special target is rough which is not shown to the subject as in CogLab subject views a list of words the list of words have something in common they are all related to a target word After viewing the list the subject must go through a set of words and identify which ones were in the just seen list some words were in the list some words were not seen including the special target Purdue University Purdue University False memory The main finding is that the special target is often identified as part of the just seen list False memory Sometimes people will even report that they recall seeing the special target not necessarily accurate we can remember things that never occurred able to be manipulated to a certain extent I can make you have certain memories but this is impossible because it was never shown CogLab data 193 participants Type of selected items Percentage of recalls In original list 75 5 These types of findings suggest that our memories are even though it was not Normal distractor not in list 7 4 Special distractor not in list 70 3 Purdue University PSY 200 Intro to Cognitive Psychology Why does the false memory effect happen Purdue University 1 Prof Greg Francis 1 2 13 False memory False memory With every to be remembered item you store some At the end of the trial you have a lot of items in memory that information but not only information about the item are related to the list Some of them are items that were actually on the list and some of them are items that were generated but not actually on the list Other information is automatically generated as well smooth bumpy road tough sandpaper jagged ready coarse uneven riders rugged sand boards ground gravel Reporting all items from memory is not going to lead to good performance Both types of memory items are real but only one type matches the physical stimuli Good performance on this task requires discrimination between Memory Item 1 Memory Item 2 Memory Item 3 bumpy smooth rough smooth rough baby baby road memories generated by physical stimuli and memories generated by internal processes bumpy smooth rough tough baby nails road Source monitoring Purdue University Interference Good memory recall usually requires not only recall of an item from memory Memory Purdue University Discrimination stones jagged bumpy smooth peaks tough rough sandpaper baby nails gravel road uneven Retroactive interference RI new information prevents recall of previous information You also must identify the correct item relative to the appropriate context or time frame e g Overwriting a computer file The current trial Proactive interference PI The context of the experiment prior learning prohibits new learning Relative to an earlier event e g Learning new cultural customs At a particular moment in time Purdue University Purdue University Proactive interference May be due to a variety of effects Proactive interference Suppose you see this building as the test on the third trial You have a match in memory but is from trial 1 not trial 3 One is that memory involves discriminating new from old You may report it having been shown in trial 3 Visual memory See a set of photos In general previous trials make memory discrimination more challenging Then see a test photo and decide if new or old Memory Trial 1 Memory Trial 2 Memory Trial 3 Purdue University PSY 200 Intro to Cognitive Psychology Memory Trial 1 Memory Trial 2 Memory Trial 3 Purdue University 2 Prof Greg Francis 1 2 13 Proactive interference Release from PI One finds proactive interference for lots of memory tasks CogLab serial position experiment I looked at recall of the first letter in each list averaged across all students Proportion of times first letter is recalled Proactive interference weakens for different stimulus types Run two Brown Peterson type experiments 1 0 95 0 9 Control 0 85 XJF Trial 1 XJF WRM Trial 2 WRM DBL Trial 3 DBL NRX Trial 4 0 8 0 75 0 7 0 65 0 6 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Trial Purdue University Release from PI Experimental group shows release of PI on Trial 4 100 60 Many kinds of stimuli NICE SUNNY ENJOY PUPPY vs NICE SUNNY ENJOY KILL Experiment 20 News stories 0 2 3 4 Trial Purdue University Every memory system must have at least two components processes Working memory We have described proactive interference as being due to difficulty discriminating new items from previous items But there is an alternative explanation Proactive interference might prevent items from being stored and thereby make them unrecallable Purdue University PSY 200 Intro to Cognitive Psychology For example working memory has a storage interference hypothesis for the phonological loop retrieval D D D D vs D D D F Purdue University Storage Works for many kinds of memory tasks Control 40 Memory system 5 7 9 1 vs 5 7 9 HAND 80 1 942 Purdue University Release from PI Trials 1 3 show build up of PI Percentage correct Experimental Working memory suggests that interference can occur by blocking ACP rehearsal articulatory suppression Brown Peterson task word length effect within the PS when items sound similar both of these block the storage of items items fall out of the loop Purdue University 3 Prof Greg Francis 1 2 13 Testing models Interference at recall Test location of PI by changing instructions after the list is presented If PI prevented the last item from being stored your telling a subject that the fourth item was an indoor sport should make no difference other than guessing Experiment stimuli are names of indoor and outdoor games Trial 1 FOOTBALL subjects usually do not notice that word on the fourth trial is an indoor game and others are outdoor games Trial 2 SOCCER Trial 3 BASEBALL Take two groups of subjects Trial 4 one has traditional PI type experiment but it makes a big difference they show release from PI Percentage correct WALLYBALL one is told of difference on


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