Purdue PSY 20000 - Lecture notes (4 pages)

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Lecture notes



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Lecture notes

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4
School:
Purdue University
Course:
Psy 20000 - Introduction to Cognitive Psychology
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Professor Greg Francis 8 14 12 Mental representation Mental imagery PSY 200 Greg Francis How do you mentally represent knowledge concepts prototypes exemplars propositions Lecture 24 mental images maps Is a picture in your head like a picture in the world Purdue University Purdue University Images Perception image how do we of perceived stimuli represent the sights information in the smells image touches analog copy of image in head and we can retrieve it sounds When we see this We have knowledge about and memories Are these converted into propositions or concepts symbology convert to propositions concepts or is there something else Purdue University Purdue University Images I can remember the image on the previous slide and it Images Runs to wears shorts girl ball If you ask me questions about the previous slide my answers would not necessarily identify the representation feels like I picture Runs to wears the image in my head shorts girl but is it really ball Mental could it be a proposition Observable Purdue University PSY 200 Intro to Cognitive Psychology There was a girl running to a soccer ball She wore red shorts Purdue University 1 Professor Greg Francis 8 14 12 Working with images Pure propositions Let s look at the arguments for a purely propositional representation If this image was printed on a piece of paper you would have no problem answering the questions about it Look at this picture I ll ask you questions about it If you had an exact copy of the image in your head you would expect you could look at the copy and make all kinds of judgments but you cannot how you interpret the image to a large extent determines what you know about it Mental images are not exactly like real images this tends to be particularly true for memory of images verbal descriptions dominate memory for images Purdue University Purdue University Another example Another example Answer these questions How did you do Which is further North Seattle Washington or Montreal Canada Which is further East Detroit Michigan or Indianapolis Indiana Which is further South Boston Massachusetts or New York City New York Which is further West Reno Nevada or San Diego California Purdue University Purdue University Propositions Propositions So this suggests that mental images are not exactly like real images and something like propositional information likely influences reports that are ostensibly based on mental images or mental San Diego maps in agent San Diego is in California object but is it all propositions are there mental images as we tend to experience them Nevada relation in object California is west of Nevada agent relation California It is clear that propositional information influences mental imagery relation Is there any reason to believe that mental images are at all analogous to real images yes Reno is in Nevada agent West Reno Purdue University PSY 200 Intro to Cognitive Psychology Purdue University 2 Professor Greg Francis 8 14 12 Representation of mental images Representation of mental images Imagine you have a mental image of a lion Imagine you have a mental image of a lion If the mental image is a depiction then it should include factors such as head mane ears and their sizes and relative positions If the mental image is a description set of propositions then it should include descriptive information head mane ears whiskers tail self reports of mental images suggest the depicted version but how to measure experimentally size of body parts shouldn t matter much except as information in the proposition Purdue University Purdue University Representation of mental images Representation of mental images Kosslyn 1976 Ask subjects to quickly answer questions like Does a lion have a head big body part Does a lion have claws small body part Subjects that did not form a mental image respond more quickly to the claws question than the head question presumably because the propositions about a lion having claws are more accessible in some network of propositions subjects in two groups 1 form a mental image of a lion 2 think about a lion but without a mental image Subjects forming a mental image respond more quickly to the head question than the claw question presumably because the head is bigger in the mental image So different ways of thinking about a lion can lead to different patterns of access to information which implies mental images are different than propositions 1600 1400 1200 Reaction time ms Reaction time ms 1600 Imagery No imagery 1000 800 600 400 200 1400 1200 800 600 400 200 0 0 Small part Big part Small part Purdue University Big part Purdue University Mental rotation Mental rotation Imagery No imagery 1000 Shepard Metzler CogLab experiment 163 participants 1971 3 D shapes The more rotated the stimuli are the longer rotated in plane it takes to make a or in depth response close to linear increase in RT decide if shapes are same are different measure time to decide Purdue University PSY 200 Intro to Cognitive Psychology Purdue University 3 Professor Greg Francis 8 14 12 Mental rotation This type of experiment has been taken as strong evidence that mental images are not just propositions Vividness There are individual differences in reports of mental image vividness imagined movement of the mental image rotation resembles actual movement some people report their mental images are just like real images It takes time to mentally move through a mental space some people report no mental images at all 10 others report they are fuzzy and vague The CogLab data suggests it is about 100 degrees second Nevertheless people all do basically the same on many tasks that seem to require operating on mental images 10 milliseconds for each degree no reason why propositions would give data that incorporate spatial and temporal relations between aspects of the mental images Purdue University Purdue University fMRI Hugdahlet al 2006 had subjects perform a mental rotation task or a comparison task did not require rotation fMRI Compared to the 2 D condition the 3 D condition has more activity in the superior parietal lobes in an fMRI scanner Males Females Purdue University Purdue University Conclusions Mental representations of pictorial information There are some things you cannot do with mental images Propositions are important Mental images are not just propositions Mental rotation task Purdue University PSY 200 Intro to Cognitive Psychology Next time Consciousness Dualism Artificial intelligence Qualia Do


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