Mental Imagery Chapter 10 PDF

Mental Imagery Chapter 10  Mental Imagery Mental Imagery: Our ability to create a sensory experience in the absence of an actual stimulus. □ In the case of visual imagery this means creating a picture or movie in your head. □ Mental imagery engages perce...

Mental Imagery Chapter 10  Mental Imagery Mental Imagery: Our ability to create a sensory experience in the absence of an actual stimulus. □ In the case of visual imagery this means creating a picture or movie in your head. □ Mental imagery engages perception, perception attention, attention and short and long-term memory to construct the experience. □ These images can be about actual remembered events (walking down a beach) beach), or complete fabrications (walking down a beach with a super model). □ Huge individual differences in mental imagery ability; some people l are great at iit, others h can’t ’ ddo iit at all. ll  Mental Imagery Propositional versus Depictive Representations Propositional: Representation using abstract symbols or factual knowledge (2+2=4; “I have a stapler on my desk”). Depictive: Representing information as a picture that can be scanned (imagining your desk then looking for a stapler).  Mental Imagery Propositional versus Depictive Representations Propositional: Representation using abstract symbols or factual knowledge (2+2=4; “I have a stapler on my desk”). Depictive: Representing information as a picture that can be scanned (imagining your desk then looking for a stapler). Which representation we use depends on what we are trying to do. Do German Shepherds have floppy ears or upright ears?  Mental Imagery Propositional versus Depictive Representations Propositional: Representation using abstract symbols or factual knowledge (2+2=4; “I have a stapler on my desk”). Depictive: Representing information as a picture that can be scanned (imagining your desk then looking for a stapler). Which representation we use depends on what we are trying to do. How many windows are in your parents’ living room?  Mental Imagery Propositional versus Depictive Representations Propositional: Representation using abstract symbols or factual knowledge (2+2=4; “I have a stapler on my desk”). Depictive: Representing information as a picture that can be scanned (imagining your desk then looking for a stapler). Which representation we use depends on what we are trying to do. □ Using Us g mapsaps o often te involves a depictive representation to p reason about spatial relationships.  Mental Imagery Shepard & Metzler (1971) Methods: Showed subjects pairs of block objects and asked them if they were the same or different. □ When theyy were different, they y differed in shape (C); no amount of rotation can line them up. □ “Same” Same objects had the same shape but differed in rotation. □ The difference in rotation was manipulated from 0 0-180 180 deg (in 20 deg increments). On some trials it was small (A), and other trials it was large (B) (B).  Mental Imagery Shepard & Metzler (1971) Predictions: If the objects were represented using a depictive code, then larger angular separations should produce longer RTs. □ A propositional representation predicts no effect of angular separation. p  Mental Imagery Shepard & Metzler (1971) Results: RTs increased with the angular separation between the objects; e.g., subjects needed only 2 seconds to say that two patterns separated by 40 deg were the th same, but b t needed d d 4 seconds to say that two patterns separated p p byy 140 deg were the same.  Mental Imagery Shepard & Metzler (1971) Conclusion: Subjects were solving this task by mentally rotating one object until it matched the other. The speed of the mental rotation operation is about 40 degrees per second.  Mental Imagery Kosslyn (1973) Methods: Had subjects study a picture (e (e.g., g boat) boat), then to form a mental image of it and “look” at a particular part (e.g., the anchor). Subjects then answered a question about b t another th object bj t either ith Near N ( (e.g., cabin) bi ) or Far F (e.g., ( motor) from their starting point. Prediction: If imagery is spatial, spatial like perception perception, then RTs should be longer to questions about far things due to subjects having to scan over a greater distance.  Mental Imagery Kosslyn (1973) Results: Subjects took longer to respond to far objects than to near objects. Conclusions: A mental image is spatial (pictorial); we “scan” a mental image just like we would scan an actual picture. □ It takes slightly longer to move our inner “eyes” eyes to more distant things, just as it would our actual eyes.  Mental Imagery Pylyshyn (1973) One doesn’t doesn t have to assume a depictive representation or mental scanning to explain data from imagery exps; data can be explained in terms of a propositional code. Assuming that time is needed to travel along each link in a knowledge structure, it should take longer to reach “motor” than “porthole” porthole when starting at “anchor” anchor.  Mental Imagery Kosslyn, Ball, & Reiser (1978) Methods: Subjects studied the locations of landmarks on a map, then created a mental image. They were then told to start at one location (e.g., tree) and to imagine a dot moving i tot another th location l ti ((e.g., mountain), t i ) th then tto press a button when they reach it. □ E Each h pair i off objects bj t h had da different distance, and every object pair was tested.  Mental Imagery Kosslyn, Ball, & Reiser (1978) Results: The time needed to scan between two objects in the image increased linearly with the distance between those objects. □ Subjects needed less time to move their mental eye when the distance was short compared to when it was long. Conclusions: Subjects form a depictive representation and mentally t ll scan it much h as they would an actual p picture.  Mental Imagery Pylyshyn (2003) Subjects may be using their tacit knowledge of how physical systems work to implicitly guide their behavior during a mental imagery task. Because subjects know that it should take longer to scan between two objects as their distance increases, they were unconsciously making their behavior conform to this relationship.  Mental Imagery Finke & Pinker (1982) Methods: Subjects would see a display of dots dots, followed by an arrow. Their task was to indicate whether the arrow pointed to one of the dots. □ There was no mention of mental scanning or of this being an imagery experiment.  Mental Imagery Finke & Pinker (1982) Results: The time that subjects took to make their judgment increased with the distance between the arrow tip and a dot in the previous display. Conclusion: Subjects formed a mental image of the dot display, then scanned from the arrow to see if it hit a dot. □ A Argued d against i t tacit t it kknowledge l d bbecause subjects bj t h hadd no reason to believe that distance was relevant to the task.  Mental Imagery LeBihan et al. (1993) Methods: Subjects were either shown an object or asked to imagine the object. fMRI was used to measure brain activation in visual cortex under each condition. Results: Visual cortex activates when seeing or just imagining an object. Conclusion: C l i I Imagery activates the same brain areas used in perception; not what you would expect from a propositional code code.  Mental Imagery Bisiach & Luzzatti (1978) Methods: Had subjects with visual neglect imagine standing at a certain location in a famous piazza, and to describe the buildings that they “saw”. People with visual neglect ignore or neglect visual information appear in their left visual field due to injury to their right parietal cortex.  Mental Imagery Bisiach & Luzzatti (1978) Methods: Had subjects with visual neglect imagine standing at a certain location in a famous piazza, and to describe the buildings that they “saw”. Results: Subjects only described the buildings that would have appeared in their right visual field field. Methods: Asked subject to imagine viewing the piazza from the opposite direction. Results: Now they described the b ildi buildings th thatt th they h had d previously i l ignored.  Mental Imagery Implications of Mental Imagery for Memory (Paivio, 1963): Some words in a Dual Code Theory (Paivio memory experiment can just be coded propositionally (abstract nouns, “idea” or “justice”), others can be coded using i b both th propositional iti l and d pictorial i t i l codes d ((concrete t nouns, “dog” or “George Washington”).  Mental Imagery Implications of Mental Imagery for Memory Reality Monitoring (Johnson et al al., 1979): We may occasionally confuse something that we only imagined for something that we actually experienced. Reality monitoring it i iis a ttechnique h i ffor di dissociating i ti memoriesi ffor real events from memories of imagined events.  Mental Imagery Johnson et al. (1979) Methods: Had two groups of subjects subjects, “good good imagers imagers” and “bad imagers”. □ Stimuli were either pictures or the corresponding words. □ Subjects would see a long sequence of pictures and words, all mixed together. □ Their task was to remember these items, items but they were also asked to create a mental image when seeing just the word. □ Finally, they were given a surprise test and asked to estimate how often they had seen the pictures (not the words). words) APPLE C CHAIR  Mental Imagery Johnson et al. (1979) Methods: Had two groups of subjects subjects, “good good imagers imagers” and “bad imagers”. Prediction: Good imagers would find it harder to give an accurate estimate of pictures because they would get confused as to whether they had seen an object or just imagined itit. Results: Good imagers were more likely to overestimate how often they had seen pictures compared to the poor imagers. APPLE C CHAIR