PSY 200 Exam III Study Guide
PSY 200 Exam III Study Guide PSY 200
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This 17 page Study Guide was uploaded by Kathryn Chaffee on Thursday February 4, 2016. The Study Guide belongs to PSY 200 at Purdue University taught by Gregory Francis in Fall 2015. Since its upload, it has received 34 views. For similar materials see Cognitive Psychology in Psychlogy at Purdue University.
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PSY 200 EXAM III STUDY GUIDE Lecture 17: Encoding Specificity 1. Part-set cuing experiment: In a part-set cuing experiment, the subjects are split into two groups. The first group is given part of a set of information that has been learned, and the second group is given no items. Both groups are supposed to recall as many previously learned items as they can. Researchers find that the group that has been given part of a set of information recalls fewer of the remaining items than the group with the normal free recall. This is because the first group has interference when they have to keep checking if an item they recall is already on the list. The effect of part-set cuing suggests that to measure memory we must consider the conditions at test. 2. Memory is similar to visual search because it is more often about discrimination of memory traces and not about the strength of memory traces. In the visual search, it is easier to find the target when there are less distractors and we only have to search through one type of search (feature search). It is the same case with memory; it is easier to access memory when we only have one task at hand, and can eliminate any extra information that can interfere with what we are trying to retrieve. 3. Encoding specificity principle: According to the encoding specificity principle, to maximize recallability, the effort and conditions at the time of learning must be consistent with the properties and conditions of the test. i. In one experiment, subjects were separated into two groups. The two groups see the same words, but have different tasks. Since they have different tasks, this changes the encoding of information in memory. One group encodes the information using semantic judgment in which they determine if the word makes sense in a sentence, whereas the other group encodes the information using rhyme judgment in which they determine if the word rhymes with a given word. Each of the two groups is then split up into two subgroups that vary in the recall of information. In the normal recognition test, those who studied using semantic judgment recalled more words than those who used rhyme judgment. The other group was tested using rhyme judgment. The group that studied using semantic judgment and was tested using rhyme judgment did worse than the group that studied rhyme judgment and was tested using rhyme judgment. The results were not because one learning/testing strategy is better than the other, it is because the encoding of information and the recall of information need to match. ii. In another experiment, deep-sea divers are divided into two groups: those that learn words on land and those who learn words under water. Then, the divers are tested for recall on land or under water. The divers that studied on land and tested on land had better recall than the divers that studied under water and tested on land. Additionally, the divers that studied on land and tested under water did worse than those who studied under water and tested under water. This is significant because divers want to remember the decompression tables when they are under water, but they generally study these tables while they are on land. Also, researchers working under water have difficulty remembering their details on land. 4. Encoding specificity principle makes it very difficult to determine if something is forgotten: Changing the context may allow the subject to recall seemingly forgotten information. Forgetting is not always a characteristic of a memory system, or your brain. Forgetting must be defined operationally. You must specify the task and context of retrieval. You can never be certain that if you are placed in a different context you will show forgetting. We cannot know if we actually forgot something or if we are unable to recall the information because it was encoded in a different context. 5. ** 6. In the experiment studying the effect of classrooms, subjects studied words in one of two contexts (on separate days). The classroom and dress of experimenter was varied. The subjects then recall all the words in the context of Day 1 or Day 2. Subjects that studied in the Day 1 context and tested in the Day 1 context recalled more words than those who studied in the Day 2 context and tested in the Day 1 context. Also, subjects that studied in the Day 2 context and tested in the Day 2 context did better than the subjects that studied in the Day 1 context and tested in the Day 2 context. Therefore, recall was better for words that were studied in the test context. When tested in the same room that we study, we have greater recall than if we tested in a different room or studied in a different room. Lecture 18: Memory Discrimination 1. False Memory CogLab experiment: This experiment demonstrates one methodology that biases people to recall things that did not occur. The memories associated with experiments of this type are often called false memories. The task is like many other memory experiments. A sequence of words is presented (verbally or visually) and the participant must subsequently classify a set of words as either in the sequence (old) or not in the sequence (new). What differentiates this experiment from other memory experiments is that the sequences are specially designed to bias participant to report a particular word that was not included in the list. The words on the list 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 of the words are actually in the list and some words were not seen, including the special target. The main finding is that the special target is often identified as part of the just seen list, even though it was not. Sometimes, people will even report that they recall “seeing” the special target, but this is impossible because it was never shown. These types of findings suggest that our memories are not necessarily accurate; we can remember things that never occurred. Also, memories are able to be manipulated to a certain extent. When people report that one of these words was in the sequence but it really was not, they are having a false memory. In some cases, people will report that they vividly recall seeing (or hearing) the word, so their memories are very strong, despite their inaccuracy. Good performance on this task requires discrimination between memories generated by physical stimuli and memories generated by internal processes, an idea known as source monitoring. Good memory recall usually requires not only recall of an item from memory, but also identifying the correct item relative to the appropriate context or time frame (the current trial, context of the experiment, relative to an earlier event, or at a particular moment in time). 2. Retroactive interference – new information prevents the recall of previous information Ex: Overwriting a computer file Proactive interference – prior learning prohibits new learning Ex: Learning new cultural customs 3. As we are given more and more trials in a memory experiment, the performance becomes worse because it becomes harder to make the judgment as to whether the object was shown on a certain trial because more information is filling up in memory. In general, previous trials make memory discrimination more challenging because there is more information in our memory that we have to discriminate between. In the data, it is shown by the decrease in proportion of times that the first letter is recalled in each subsequent trial. Memory performance gets worse as each trial progresses. 4. When the proactive interference weakens when a different stimuli is introduced, it is called the release from PI. In a Brown- Peterson type experiment, the first three trials are the same trigram of letter for both the control and experimental groups. In each subsequent trial, both groups had worse recall. In the fourth trial, the control group was shown a fourth trigram of letters, whereas the experimental group was shown a number. Changing the stimuli for the fourth trial provided the experimental group with a release from PI and they had better recall on the fourth trial than the control group that was still experiencing PI. 5. 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 6. Indoor vs. Outdoor Sports Experiment: In this experiment, we test the location of PI by changing instructions after the list is presented. The stimuli in the experiment are names of indoor and outdoor sports. The subjects usually do not notice the word on the fourth trial is an indoor sport and the others are outdoor sports. First, the subjects are separated into two groups. One of the groups has the traditional PI type experiment in which the fourth trial is an indoor sport instead of an outdoor sport (as in trials 1-3). The other group is told of the difference on the fourth trial at the time of test. Does the hint help? If PI prevented the last item from being stored, the hint should make no difference. But, it makes a big difference, thus showing a release from PI. Proactive interference affects the ability to recall information, not affecting your ability to put the information into memory. 7. Yearbook study of long-term memory: In the experiment, 392 subjects brought in their high school yearbook and were asked to match names with faces or recall names for faces. Subjects did better on the name matching task than they did on the picture cueing task. Researchers also found that subjects did worse when a longer period of time had passed since high school. One can suggest at least two explanations for poorer memory as time elapses: 1) Retroactive interference from subsequent faces/names 2) The mental representation of temporal position becomes blurred as a function of time Recent events are easy to discriminate in time Long ago events are difficult to discriminate in time Lecture 19: Constructive Memory 1. The task of eyewitness testimony is difficult because you have to do several things: i. Recall information that might be related to the task from memory ii. Determine if the memory is actually from the correct event iii. Determine if the memory is actually for the correct moment in time iv. Gauge your confidence in the memory’s validity Memory in an eyewitness task is constructive because it involves discriminating information in order to report memories. 2. Penfield: Penfield found that when certain parts of the brain were stimulated, conscious patients report vivid memories that they are unable to recall normally (Ex: woman saw herself as she had been while giving birth to her baby). This experiment suggests that memories are stored but normally unreachable because of the current context. The experiment was the basis for ideas of memory repression. But, the results are usually misunderstood and this actually only occurred for 5% of patients. Also, the memories are nearly impossible to verify, and they found that the memories were often not true. The cognitive experience the patients undergo may be due simply to the brain being stimulated. The patients have epilepsy, meaning that the stimulation may have triggered something like an epileptic seizure, which may lead to hallucinations. It is more likely that stimulation “feels like” a memory, even though it is not. Our awareness of “remembrance” is a product of our brains. It can be stimulated, even without a real memory. 3. Flashbulb memories: Highly emotional events tend to produce strong memories. People vividly recall the details surrounding the event (where they were when they heard, what people said, clothing worn, time of day). People are confident about their reports. In an experiment conducted on September 12, 2001 on flashbulb memories, researchers asked volunteers to answer questions about their memory of the WTC attack or an ordinary event of the volunteer’s choice. Then, they follow up with each volunteer either 7, 42, or 224 days later and ask them to recall the details of the WTC attack or the ordinary event. The amount of consistent details decreases as the number of days increases. The recalling of details was the same for the WTC attack and the ordinary event. When the subjects are asked about the characteristics of these memories, we find that the subjects report that their memory of the WTC attacks were more vivid, and subjects were more likely to believe that their memories were reliable. In contrast, the ordinary memories faded in vividness and their belief in reliability decreased over time. The subjects’ confidence in their memory can be misleading. The retelling of the story probably reinforced the story, but it may not be the true memory. Flashbulb memories are a real phenomenon about the experience of memory. 4. Loftus & Palmer experiment: In the experiment, a subject watches a series of slides. Then, you split the subjects into two groups and ask the groups some questions based on what they saw on the slides. Most questions are innocuous questions. Then, one question differs between the two groups. One group is given a misleading question, such as “Did you see the car stopped at the stop sign?” After the question period, they are shown slides and are asked to determine if it is new slide or old slide. One of the slides is related to the misleading question, showing a stop sign instead of the yield sign like it was in the original slides. The misleading question changes our memory in which we think that the yield sign shown in the original slides is actually a stop sign because it was implied in the misleading question. Subjects without a misleading question had 90% accuracy when they were asked if the slides were in the original set. However, subjects with a misleading question only had 20% accuracy. In a follow-up, the experimenters asked those with misleading questions if they thought they were mislead and 90% of them said no. In addition, the misinformation effect gets stronger with a week delay before the memory test. The experiment shows that eyewitness testimony can be easily influenced by the “misinformation” effect. 5. Loftus has a procedure that “implants” a memory of being lost in a mall. Basically, just have the subject read a plausible story (with some details that could be true) and get family members to pretend the story is true. Later, the subject “remembers” the story as something that happened to him/her. It is very easy for a therapist to “implant” false memories into patients. Lecture 20: Amnesia 1. There is no method other than object physical evidence to verify the accuracy of a memory. Memory is a cognitive experience. Confidence in our memory is another cognitive experience. This implies that you can have different combinations of the validity of the memory and your confidence in the memory. That is, you can be very confident in the memory and still be wrong. Many memories are constructions based upon pieces of evidence put together into a coherent story. We really can’t trust our memories unless we have object physical evidence. 2. Amnesia is the loss of memory or memory abilities. Retrograde amnesia – forgetting events prior to the injury Anterograde amnesia – forgetting events after the injury 3. 5 months after the accident: don’t remember anything 2 years prior to the accident up until after the coma, and events from infancy are somewhat fuzzy; remember events that occur after the accident 8 months after the accident: don’t remember anything 1 year prior to the accident and 4 years prior to the accident are somewhat fuzzy; patients tend to remember infancy and events that occur after the accident 16 months after the accident: don’t remember anything 2 weeks prior to the accident, but memories prior to two weeks before the accident and after the coma are still available The difficulties in studying retrograde amnesia is because we really don’t know what would happen if they were not fed any information, because we cannot verify any of the memories. 4. Declarative (explicit) memory is the memory involved in episodic memories (events in personal past) and semantic memories (general knowledge). Non-declarative (implicit) memory is procedural memory, involved in skills/habits. 5. Patient HM had anterograde amnesia; therefore, he was unable to learn anything new. Patient HM was able to preserve past memories but was prevented from forming new memories. HM thought it was 1953, shocked by the age of his face in his mirror, could not stand to read newspapers, and reintroduced himself to doctors and nurses everyday. But, HM could learn some things. He would claim to not know where the hospital cafeteria was located, but would automatically walk to it. He learned, but did not realize he learned. His ability to learn is also shown in the mirror drawing task. On the first day of the mirror drawing task, HM attempted to draw the star and had many errors. On the second day, HM had no knowledge of ever doing the task before, but had fewer errors than the first day. On the third day, he had even less errors, still stating that he had never completed the task before. This experiment shows that he learned how to do the task, but doesn’t remember that he learned it. The task can be seen as procedural memory. 6. In an immediate serial recall test, anterograde amnesiacs have a fairly normal STM digit span, but it is very difficult to extend the digit span. This shows that anterograde amnesiacs have problems with their LTM. In the serial position curve, anterograde amnesiacs show normal recency and abnormal primacy. The primacy affect decreases for amnesiacs because of their issues with LTM. 7. Infantile amnesia refers to the idea that we can only remember back to age 4. This is because of encoding specificity. We are in a very different context now than we are at age four and younger, and thus, have difficulty recalling the information. Children younger than four year olds view the world differently than adults. By encoding specificity, one needs to be in a similar state as study to best recall something. Adults are very different from children, and this prevents the recall of early memories. 8. Repression: Repression is the idea that we can prevent painful memories using psychological defense mechanisms. Psychotherapists suggested that infantile amnesia occurred because much of childhood is filled with painful events and memory of the pain is prevented by psychological defense mechanisms. This is very unlikely because people do remember painful events well and laboratory studies find no evidence of repressed memories. In a laboratory, showing evidence of repression requires (1) being unable to remember something, (2) being able to recover the memory through therapy, and (3) proving that the recovered memory is accurate. In therapy, clinicians often claim evidence of repression with dream interpretation, patterns in symptoms, and recovering a memory through hypnosis. However, none of these techniques demonstrate a verified memory. Among carefully controlled memory research, there is no evidence of repression. Lecture 21: Improving Memory 1. We know that memory is best when the study and test contexts are similar. For example, testing in the study classroom often leads to better recall. But, variability in the study contexts promotes more general recall. In an experiment by Smith, subjects studied words twice: either in the same context or different contexts, with a three-hour interval in between the contexts. Then, the subjects were tested in a neutral context after another three-hour interval. The results show that the recall is the highest for the subjects who studied in varying contexts. That is, if you want to remember something in a lot of contexts, study in a lot of contexts. 2. Memory can be influenced by the depth of processing at the time of study. The more deeply processed the information is, the better recall we have of the information. For example, if we are just given a list of words to commit to memory without using any task to remember them, we are less likely to remember than if we had done some sort of task to remember them (processed them further). A study by Craik and Tulving shows the idea of the relationship between memory and levels of processing. In the study, subjects observe words with associated tasks. The three different questions the subjects have to answer about each word differs in the amount of processing of the word. The three questions are asking whether the word is in capital letters, whether it rhymes with a specific word, or if it is a synonym for a certain word. Each of these questions, respectively, increases in its level of processing needed. The results found that recall is better as depth of processing increases. That is, subjects who used synonyms had greater recall than the subjects who used rhyming, who also had better recall than the subjects who used capitalization. The synonyms task require more processing, which creates more distinctive memories that helps subsequent recall. By varying the depth of processing, you can construct memories that are more likely to be recalled. 3. In an experiment by Hyde and Jenkins, the idea that levels of processing is more important than the intent to learn was studied. The subjects were separated into 11 groups: 1 control group and 10 experimental groups. The control group were told that they were going to be tested to recall the words, but we not given any study task. The 10 experimental groups were assigned certain study tasks: Pleasant-unpleasant rating Estimate frequency of word usage E-G checking (does word contain E or G?) Identify part of speech Sentence framing (which sentence does word best fit in?) For all the experimental groups, they had intentional learning in which they were told they would be tested to recall the words or incidental learning, in which they were not told they would be tested. The results show that recall varies a lot with each task. However, there is not much variation in recall between those with intentional learning and those with incidental learning. In addition, people do not know the best way to remember. It is important to study interactively to improve recall because we are not certain as to which method helps us remember the information the best. 4. Judgment of learning (JOL) is the estimation of how likely we are to be able to recall information. It is basically trying to decide if we have learned the material and if we would be able to remember the material if we are tested on it later after studying. In the experiment on JOL, subjects were told to study a pair of words, and estimate how likely they are to be able to remember one word if shown the other (JOL). This is the subject’s estimate of their ability to use LTM. The subjects either make this JOL immediately after studying the pair or later in the experimental trials. The results show that immediate JOLs do not match memory performance, especially for high JOLs. Delaying the JOL leads to fairly accurate JOLs. In order to make the JOL more accurate, it is best to wait some time after studying before you make the JOL because it will be more accurate. 5. A common approach to studying is to use flash cards. There are two steps for studying: (1) Read material on both sides, and (2) Practice test the material. In a study on recall practice, subjects study 40 Swahili – English word pairs. There are four groups of subjects that differ after an item is correctly recalled: ST (study test) – subject studies and continually tested over every pair SnT (study on non-recalled, test on all) – when a subject recalls a pair, it is no longer studied, but it continues to be tested STn (study all, test only on non-recalled) – when a subject recalls a pair, it continues to be studied, but it is not tested SnTn (study on non-recalled, test on non-recalled) – when a subject recalls a pair, it is not studied or tested again The subjects are tested a week later. The standard advice is that once you learn something, study something else; however, it is not good advice. Performance is best when every pair is tested, even if you have already demonstrated it is memorized. The amount of time spent studying the words does not matter so much. The groups that had the best recall were the ST and the SnT, meaning that the amount of time spent studying doesn’t have much of an effect; instead, it is continuous testing that allows us to have the best recall. The results suggest that we learn how to recall the information. 6. A common approach in education is to identify a student’s learning style and then teach for that style. There are lots of tests to identify a student’s learning style, and there do seem to be real differences in what style people indicate that they prefer. Unfortunately, there is absolutely no evidence that reported learning style preference has anything to do with learning. Pashler observed that to demonstrate evidence that learning style influenced learning, you have to show a particular kind of interaction of effect. Pashler then reviewed hundreds of studies purporting to show evidence for learning styles, but only ever found effects like these. But these only indicate an advantage for a type of learning or a method. Lecture 22: Improving Memory 1. SF: SF learned to increase his digit span to 79 digits (any random sequence) by practicing for 230 hours (over 20 months). He did this by breaking down and organizing each digit list, eventually creating a hierarchy of tricks (ages, dates). However, this technique did not transfer to other memory tasks. This memory trick is known as grouping. 2. Method of loci: The method of loci is used to remember lists of words or key ideas. In order to do this, a person must: i. Visualize walking around an area with distinctive landmarks ii. Link the items to be remembered with landmarks using bizarre mental imagery iii. To recall items in order, mentally walk through the area Any ordered sequence will work. Memory piggybacks on the easy recallability of the bizarre imagery. 3. In the peg word system, you associate items in a list with a previously memorized list. For example, one is a bun, two is a shoe, three is a bee, ect. In this system, people recall the items by reciting the poem. The “hook” is the item on the list that needs to be remembered. Visual imagery also helps to recall the items. In the link word method, we find an English word that sounds like some part of a foreign word, and form a mental image of the key word interacting with the English translation of the foreign word. For example, pato is the Spanish word for duck and sounds like pot-o. Therefore, you could imagine a duck with a pot on its head. Imaginging such a vivid, bizarre picture helps us to learn the association between the Spanish and English words. 4. Brain training: Several companies market activities to make you smarter by “exercising” your brain with games that are adapted from neuroscience. The games are often aimed towards elderly and young children. Much of the hype comes from a study that trained people for a few hours on a dual-n-back task. This task asks “does the current stimulus match the one from n trials back?” and n is adjusted for each person so the task is always demanding. Also, n is a measure of how well subjects do the task. Subjects do get better at the n-back task with training. Transfer effects for a measure of fluid intelligence (refers to the ability to reason and solve new problems independently of previously acquired knowledge. The results show that the training group does better than a control group, and the amount of n-back improvements is related to gain in intelligence. Redick cautions that the conclusions are based on 4 small studies that varied in many ways and that it is probably a mistake to average scores across these studies. There was also some selective reporting of measures of fluid intelligence; measures that did not show an effect were not reported. Also, there was no comparison to an “active control” where subjects complete a training task that should not improve fluid intelligence. You should be similarly skeptical about claims for improving attention, perception, and other mental capabilities. You can improve performance on specific tasks, but that doesn’t typically transfer to other tasks. You can make yourself smarter by learning new information. 5. ***In the study on sleep by Ellenbogen, subjects learn to identify order relationships between “random” shapes. The subjects are only shown one pair at a time, and subjects have to learn/memorize the appropriate answer to each pair. There is an ordered arrangement to the stimuli, and if you know the arrangement, deciding for any pair is easy, but subjects are never explicitly told about this arrangement. Subjects are then split into three groups, according to when they are tested (20 minutes later, 12 hours later, 24 hours later). There were no differences when they were tested on the originally studied items, but there are big differences when they are tested on new pairs that fit the ordered structure. Subjects that were tested after 12 and 24 hours had a much higher percentage correct than the subjects who were tested 20 minutes after. Half of the 12-hour group had sleep and half did not. It makes a difference for pairs of items that are far apart in the ordered structure. Lecture 23: Mental Representation 1. Definition approach to concepts: The definition problem is that for any definition that someone can come up with, you can find examples that do not seem to fit the definition. But, we all know what a shoe is, so our knowledge of this concept must not be based on some precise definition. Sometimes scientists can create precise definitions, but the definition is somewhat arbitrary. 2. Prototype theory of concepts: The prototype theory supposes that similarity among items is judged relative to a prototype example of the concept (e.g., an ideal, average, or most frequent version of the concept). In prototype theory, it is possible for an object to be “more” or “less” a certain concept (Ie; a coffee cup). 3. CogLab version of Posner & Keele experiment: In the experiment, subjects are learning category names for random dot patterns. On each trial, subjects discriminate two sets of random dot patterns. Each pattern is a variation of one of two prototype patterns. Variations are made by moving some of the dots. The subjects learn to classify many different variants, but they never see the prototypes themselves. The key test is done after subjects learn to classify the variants. The reaction time for judgment is recorded for stimuli the subjects have never seen before. They are shown either new variants or they are shown the prototypes themselves. The reaction time is faster for the prototypes. This result suggests that the mental representation of the categories (concepts) are built to favor the prototype of the category. In our coglab data, it took us 50 ms longer to report the variants than it did to report the prototypes. This suggests that the concept we have of the way we assign the random dots is consistent with the stimulus pattern that corresponds to the way the dots have been structured. Since there is a good match between the stimulus and the concept in our head, we are able to respond quickly. If it is not a good match, it takes longer to respond. This is evidence that our concepts are prototypes. When we recognize a stimulus in our environment as a match to the prototype in our head, we respond quickly with what concept it is. 4. ***There are different concepts for things, actions, goal-derived, ect. There are also ad hoc concepts. We can generate the concepts automatically. A difficulty is that it’s inconceivable that ever possible prototype exists ready to be used. Some concepts must just be built as they are needed. 5. Exemplar theory of concepts: The exemplar theory of concepts states that a concept consists of lots of examples of the concept. According to this theory, in order to come up with a concept, we compare an object to each example in memory to see if it matches anything well enough. Even if it is a new object, it may match several exemplars well enough to generate an overall response to the concept of the object. 6. ***Some objects seem prototypical because they match lots of exemplars, but that’s what defines a prototype. 7. Propositions are higher order ideas of things doing something. Propositions are the simplest statement that can be judged as true or false, and consists of an ordered list of concepts. 8. The proposition connects the appropriate concept nodes. (relation, agent, object) Relation – threw Agent – Albert Object – Book Each of the three circles (Albert, threw, object) represent three different concepts, all connected by the proposition. 9. Ratcliff & McKoon experiment: The experiment starts with a study phase in which subjects are asked to memorize a set of 504 sentences. During the test phase, the subjects are shown words and asked to decide if they were in the study sentences or not. Researchers measured the reaction time for words from the sentences. The sentences they were given were constructed so that the subjects could break the sentence down into its propositions. In the test phase, a word is given and the subject responds as quickly as possible. The expectation is that activation will flow through the entire proposition that includes the word. So, if the next word is part of the same proposition, a subject will respond even faster. If the words are from different propositions, there is no priming and the subject will respond slower. The results show that when the words are within the same propositions, it takes about 561 ms. When the words are between proposition words, it take about 581 ms. When the words are unrelated, it takes even longer at about 671 ms. Therefore, there is evidence of priming by propositional activation. Lecture 24: Mental Imagery 1. The conflict is deciding whether the perceptual events are converted into propositions, or concepts or is there something else. 2. The limitations of what we can do with mental images imply that mental images are not identical to real images. For example, if you had an exact copy of the image in your head, you would expect that 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. 3. In the demo, we were asked to determine the relative position of cities. The idea is that we may have a mental image in our head, but the mental image is influenced by general information (Canada is north of US, so Montreal should be North of Seattle). 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 maps. 4. Kosslyn’s experiment: In the experiment, you ask subjects to quickly answer questions like: (1) does a lion have a head, or (2) does a lion have claws? The subjects are split into two groups. One group is told to form a mental image of a lion, and the other group is to think about a lion, but without forming a mental image. Subjects that form a mental image respond more quickly to the head question than the claw question, presumably because the head is bigger in the mental image. 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. So, different ways of thinking about a lion can lead to different patterns of access to information, which implies that mental images are different than propositions. 5. CogLab mental rotation experiment: Subjects are shown 3-D block shapes that are rotated in the plane or in depth. The task is to decide if the shapes are the same or different. The reaction time is measured. The mean RT is plotted against the rotation angle. The more rotated the stimuli are, the longer it takes to make a response. The results are close to a linear increase in RT. For the shapes that are different, there is no difference in the reaction times no matter how the shapes are rotated. This type of experiment has been taken as strong evidence that mental images are not just propositions. The imagined movement of the mental image (rotation) resembles actual movement. It takes time to mentally move through a mental space. The coglab data suggests it is about 100 degrees/second (10 ms/degree). There is no reason why propositions would give data that incorporate spatial and temporal relations between aspects of the mental images. 6. Hugdalh had subjects perform a 3D mental rotation task or a control task (no judgment, just look at 2D oriented bars and press a button) in an fMRI scanner. Compared to the 2D condition, the 3D condition has more activity in the superior parietal lobes. The activity in the occipital lobes is the same in both conditions. You can identify places in the brain that are used in doing the mental rotation tasks. Since it is in the parietal lobe, it is consistent with the idea that it is mental imagery as a picture.
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