Week 6 - (09.13) Reading & Lecture Notes
Week 6 - (09.13) Reading & Lecture Notes 4100
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This 5 page Class Notes was uploaded by Leslea Motley on Tuesday September 20, 2016. The Class Notes belongs to 4100 at University of Georgia taught by Kara Dyckman in Fall 2016. Since its upload, it has received 3 views. For similar materials see Cognitive Psychology in Psychology (PSYC) at University of Georgia.
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Date Created: 09/20/16
09.13 – Reading Notes – Object Recognition and Agnosia 3.3 Review the science of object recognition and agnosia 3.3.1 Recognition by Components Biederman's (1987-1990) Recognition by Components theory (RBT) o The idea is that we recognize objects by breaking them down into their parts, and then look up the combination in memory to see which object matches it o Pattern Recognition here has a small number or basic primitives – simple 3D geometric forms called geons: combined form of geometric ions o Theory argued that mental representations of 3D objects are composed of geons; when we recognize objects, we break them down into their components and note where the components join together; the pattern then matcher too info stored in memory to yield recognition – two important aspects of these patterns: Find the edges of objects, enabling us to determine which edges maintain the same relationships to one another regardless of the viewing orientation Scan vertices (regions of the pattern where lines intersect) - usually places where deep concave angles are formed Evidence for RBC In Beiderman's further investigations of this model he discovered: o Emphasis on vertices is critical If a pattern is degraded, your perception will depend on where it was degraded. If segments on smooth, continuous edges are missing, it is relatively easy to fill out the missing parts and recognize the pattern. Found using drawings with deletions and determining which deletions caused impaired perception among participants (examples of these images are in the book Figures 3-13 and 3-14) Shortcomings of RBC and Embodied Perception It is tied to bottom-up processing o Issue b/c object recognition is strongly influenced by context and prior knowledge o Example: Tanaka and Curran (2001) tested 'bird' and 'dog' experts (people with more than 20 years experience with local dog and bird organizations); these people showed enhanced, early recognition in their areas of expertise, compared to how they recognized objects outside of their areas. o Also, Evidence that retrieval of an object's identity occurs as fast as identifying that something is there at all Dell'acqua and Job (1998) - data indicate that object recognition is automatic, given that judgments of a perceptual feature were strong. Perceiving components is the first major step ion object recognition – thus, claiming that the whole is perceived by first identifying the components of the overall shape and global pattern (aka the Gestalt or overall form) 3.3.2 Context and Embodied Perception Embodied processes: how the structure of our bodies and how we interact with the world influence the way that we think Neural systems programming neural activity – including motor cortex and mirror neurons o These areas are activated under a variety of circumstances when people are looking at objects, including when perceiving/predicting the actions of other people. o We vicariously experience or enact what we see other people doing, mentally simulate how you would perform that activity People also activate mental representations of the muscle activities they would engage in if they were to interact with an object or environment o Tucker and Ellis (1998) - participants respond to pictures with left or right hand o Determined that the ease with which objects are identified can be influenced by the actions people would take to use them 3.3.3: Agnosia Agnosia: a failure or deficit in recognizing objects, either because the pattern of objects can not be synthesized into a whole or because the person cannot then connect the whole pattern to meaning o Often associated with damage to the left occipital or temporal lobes o People with agnosia ('agnosics') can see and detect visual stimuli – they are NOT blind, they are experiencing cognitive and mental loss o Not limited to vision; auditory agnosia is possible, but agnosia's are modality specific o Visual agnosia: disrupted recognition of objects presented visually, but no disruption of hearing, touch, or other sensory systems There are also subtypes of visual agnosia, each with a somewhat different type of deficit – each involved different brain regions.: Apperceptive agnosia: disruption in perceiving patterns o Still able to process rudimentary visual features – color and brightness o "..ability to coalesce this basic visual info into a percept, an entity, or a whole, it lost" (Banich, 2004) o Associated with the right hemisphere, in the parietal lobe o Cannot fill in missing contours to perceive the whole form or pattern Associative agnosia: cannot associate the pattern with meaning, not able to construct a mental percept – he/she can combine perceived features into a whole pattern, but cannot further associate that pattern with any stored memory/knowledge about its identity o Damage to corpus callosum Prosopagnosia: a disruption of face recognition o Often a result of damage to the fusiform gyrus, as well as, along the ventral stream The fact that there are two separate conditions (one involves objects and the other faces) is significant because it shows that perception is complex, and that different brain areas emphasize different qualities of info. "Perception is not a one-size-fits-all system., but is a number of specialty systems that typically work in seamless harmony." Famous case of agnosia: "The Man who mistook his wife for a hat" (Sacks, 1970) o Music professor, Dr. P, lost ability to recognize objects and faces; he was able to describe the components or elementary features of an object yet was unable to identify the object he was looking at o "..Had a serious and pervasive visual agnosia, a profound loss in the ability to recognize things." 3.3.4: Implications for Cognitive Science "What do these neurological disruptions mean for our understanding of normal perception? How does evidence advance our understanding of cognition?" Apperceptive agnosia o Serious disruption in early stage of perception, disorder of feature detection o Malfunction in the process of extracting features from visual stimuli o For example: Beiderman's, 'geons' are not processed much beyond noticing small segments or junction points o Seems to result from damage in the right hemisphere, parietal region o More involved in global processing, forming global patterns, while left pays more of a role in local processing (small components and features) o Furthering above theory --> Disrupted mechanism in forming a Gestalt mechanism from the features, where this disrupted mechanism would correspond to the symptoms of apperceptive agnosia Associative agnosia o "a deeper dysfunction" o Gestalt pattern formed but seems to have lost the pathway to the meaning and name of the object o Damaged regions are lower, towards the temporal lobe in BOTH hemispheres o "What pathway" - pathway from the vision centers in occipital lobe forward and down toward the temporal lobe – activated when you look at something and decide what it is o Temporal lobes are primarily associated with language and word meaning o Connecting from a perceived pattern to its meaning and name is the impairment in associative agnosia Varieties of agnosia define 3 important things about perception: o Detecting features in a visual stimulus is a separate (and later) process from sensation Basic features must be extracted from a sensory signal o Detecting visual features is critical in constructing a perceived pattern, a percept If features cannot be extracted, a person cannot get the Gestalt, cannot form an overall pattern or percept. o There is a separate step for hooking up the pattern with its meaning and name in memory; different from knowing the meaning and name of an object in verbal form. Visual association path can be isolated from all the other sensory systems Therefore, "immediate" recognition of objects is NEITHER simple nor immediate. Disruptions of agnosia whether caused by disruptions in feature detection of in associating patterns with meaning, provide additional evidence of the complexity of perception. 09.13 Lecture Notes Prosopagnosia - inability to recognize facial details Activity - - Finish space training - space effect on cognitive processing finished - "The Man Who Mistook his Wife for a Hat" activity
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