Studies on visual information processing have been concerned with the question of whether our non-verbal knowledge is represented in the same manner as our verbal knowledge. Many theorists have studied the issues of hemisphere specialization and visual imagery to evaluate whether verbal and visual information is represented in different ways. Now we examine these studies.
Hemisphere Specialization
The human brain is divided into two roughly symmetrical halves called as left and right hemispheres. Physiological evidence indicates that these two cerebral hemispheres :of the brain act as two separate processing systems. Right hemisphere is specialized for processing spatial information and spatial relations, whereas the left hemisphere is specialized for processing language and verbal information. For example, damage to the left hemisphere produces language disorders, called aphasias, in a high percentage of I right-handed people. Yet that damage seldom impairs spatial abilities. In contrast, damage to the right hemisphere of right-handers produces deficits in the ability to draw items to judge spatial relationships or to move about getting lost. These observations, which are backed by observations concerning the behaviour of split-brain patients, suggest that the two hemispheres may process different kinds of representations. In tum, this idea has fueled the notion that propositional representation is not the only kind of representation people use.
Images and Analog Representation
In performing everyday tasks, many people form visual images, for example, if a student asked you how to get the library or canteen, you might construct an image or mental map of your college campus and use that image to give the correct verbal instructions. Introspectively, our images seem to resemble or mirror the objects they represent. Images preserve the spatial relations that are present in the external scene.
Due to the fact that our images resemble the objects they represent, many theorists believe that images are analog representations. An analog representation is one that mirrors or is analogous to the things that are represented. Images are analogous to perception, and both involve analog representations. Visual images contain visual and spatial information that can be quite detailed. Further more mental images can be scanned and rotated, just as external objects can.
Images and Propositions
Images are based upon propositional representations. For example exact image of particular room can be represented by propositions such as BESIDE (CHAIR, TABLE) and ON (BOOK, SHELF). Propositions could indicate that a location was occupied by an item even if we were unable to picture that item. Thus images may be based upon abstract, propositional descriptions that bear little resemble to the objects they represent.
Informing images, we use our world knowledge, which is represented in propositional form. On the whole we can conclude that propositional and analog representation may be used in a complementary manner in representing our semantic or world knowledge: the kind of representation we use depends on the situation.
SUMMARY
Our cognitive activities are based upon both episodic and semantic knowledge. Episodic know ledge is autobiographical and includes memories of events and episodes that occurred at a particular time and place. Semantic or world knowledge includes factual, conceptual and linguistic information. There is no sharp distinction between episodic and semantic knowledge. Many global models represent--knowledge in a propositional format. A proposition is a symbolic expression that can be true or false and that designates a relationship between two or more concepts, as in BITE (DOG, BOY), which represents the meaning of the sentence "The dog bit the boy". People seem to represent sentences and paragraphs in prepositional form. Global models such as HAM (Human Associative Memory)use prepositional representations because they are powerful enough to embody much of our knowledge and they allow for efficient processing. Some theorists contend that our knowledge of visual objects and of spatial relationships the know ledge we use in recognizing pictures and forming visual images is not represented propositionally. The most convincing evidence that people use non-propositional representations comes from studies of visual imagery. Visual images are analogous to our visual perceptions of objects; both contain visual and spatial information that can be quite detailed. Further more, mental images can be scanned and rotated; just as external objects can. Overall, images seen to resemble the objects that they represent. Images are also based upon prepositional representations, for we use our abstract, propositional knowledge of concepts and spatial relations to construct images. In conclusion, then, our semantic or world knowledge consists of both prepositional and analog representations.
Hemisphere Specialization
The human brain is divided into two roughly symmetrical halves called as left and right hemispheres. Physiological evidence indicates that these two cerebral hemispheres :of the brain act as two separate processing systems. Right hemisphere is specialized for processing spatial information and spatial relations, whereas the left hemisphere is specialized for processing language and verbal information. For example, damage to the left hemisphere produces language disorders, called aphasias, in a high percentage of I right-handed people. Yet that damage seldom impairs spatial abilities. In contrast, damage to the right hemisphere of right-handers produces deficits in the ability to draw items to judge spatial relationships or to move about getting lost. These observations, which are backed by observations concerning the behaviour of split-brain patients, suggest that the two hemispheres may process different kinds of representations. In tum, this idea has fueled the notion that propositional representation is not the only kind of representation people use.
Images and Analog Representation
In performing everyday tasks, many people form visual images, for example, if a student asked you how to get the library or canteen, you might construct an image or mental map of your college campus and use that image to give the correct verbal instructions. Introspectively, our images seem to resemble or mirror the objects they represent. Images preserve the spatial relations that are present in the external scene.
Due to the fact that our images resemble the objects they represent, many theorists believe that images are analog representations. An analog representation is one that mirrors or is analogous to the things that are represented. Images are analogous to perception, and both involve analog representations. Visual images contain visual and spatial information that can be quite detailed. Further more mental images can be scanned and rotated, just as external objects can.
Images and Propositions
Images are based upon propositional representations. For example exact image of particular room can be represented by propositions such as BESIDE (CHAIR, TABLE) and ON (BOOK, SHELF). Propositions could indicate that a location was occupied by an item even if we were unable to picture that item. Thus images may be based upon abstract, propositional descriptions that bear little resemble to the objects they represent.
Informing images, we use our world knowledge, which is represented in propositional form. On the whole we can conclude that propositional and analog representation may be used in a complementary manner in representing our semantic or world knowledge: the kind of representation we use depends on the situation.
SUMMARY
Our cognitive activities are based upon both episodic and semantic knowledge. Episodic know ledge is autobiographical and includes memories of events and episodes that occurred at a particular time and place. Semantic or world knowledge includes factual, conceptual and linguistic information. There is no sharp distinction between episodic and semantic knowledge. Many global models represent--knowledge in a propositional format. A proposition is a symbolic expression that can be true or false and that designates a relationship between two or more concepts, as in BITE (DOG, BOY), which represents the meaning of the sentence "The dog bit the boy". People seem to represent sentences and paragraphs in prepositional form. Global models such as HAM (Human Associative Memory)use prepositional representations because they are powerful enough to embody much of our knowledge and they allow for efficient processing. Some theorists contend that our knowledge of visual objects and of spatial relationships the know ledge we use in recognizing pictures and forming visual images is not represented propositionally. The most convincing evidence that people use non-propositional representations comes from studies of visual imagery. Visual images are analogous to our visual perceptions of objects; both contain visual and spatial information that can be quite detailed. Further more, mental images can be scanned and rotated; just as external objects can. Overall, images seen to resemble the objects that they represent. Images are also based upon prepositional representations, for we use our abstract, propositional knowledge of concepts and spatial relations to construct images. In conclusion, then, our semantic or world knowledge consists of both prepositional and analog representations.