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theories [2010/04/16 00:37]
sarahsolomon
theories [2010/04/16 00:39] (current)
sarahsolomon
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 Sensory integration in a broad sense deals with the integration of input across modalities. That is, vision as integrated with audition, taste as integrated with smell, until a coherent representation can be established. However, it is important to note that integration within a modality must occur as well. This phenomenon is referred to as feature binding. ​ Sensory integration in a broad sense deals with the integration of input across modalities. That is, vision as integrated with audition, taste as integrated with smell, until a coherent representation can be established. However, it is important to note that integration within a modality must occur as well. This phenomenon is referred to as feature binding. ​
  
-==Spatially Selective Attention==+===Spatially Selective Attention===
 One theory of visual feature binding is posited by Treisman (1998). This theory can be thought of as the spatially selective attention theory of feature binding. As the name implies, features are bound together through the work of spatially selective attention, and this requires different elements in order to work. First off, there is a "​master map of locations",​ which can be thought of as a spatially represented map of the visual field. Secondly, there is a way in order to detect the presence of features anywhere in the visual field; these features are "​flagged"​ in order to signify their presence. An implicit spatial layout of the features is also included in the theory, most likely to account for implicit awareness of feature locations in the absence of spatially selective attention. ​ One theory of visual feature binding is posited by Treisman (1998). This theory can be thought of as the spatially selective attention theory of feature binding. As the name implies, features are bound together through the work of spatially selective attention, and this requires different elements in order to work. First off, there is a "​master map of locations",​ which can be thought of as a spatially represented map of the visual field. Secondly, there is a way in order to detect the presence of features anywhere in the visual field; these features are "​flagged"​ in order to signify their presence. An implicit spatial layout of the features is also included in the theory, most likely to account for implicit awareness of feature locations in the absence of spatially selective attention. ​
  
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-==Temporal Correlational Hypothesis==+===Temporal Correlational Hypothesis===
  
-A different, yet more neurological,​ account of feature binding is the temporal correlational hypothesis, in which different perceptual features are bound together by means of neural synchrony. This account relies on the neurophysiological properties of cells, and their ability to synchronize activity due to the rhythmic effects of ion conductances. A brain area that has been attributed with this property is the thalamus, which takes in sensory information from the neural periphery (i.e., sensory organs), and relays it to the cortex. In doing so, different perceptual cues are bound together due to the inherent physiological nature of the thalamic and thalamic relay cells; this can, in theory, explain how different perceptual cues are bound together into a unified representation (Singer and Gray, ???). +A different, yet more neurological,​ account of feature binding is the temporal correlational hypothesis, in which different perceptual features are bound together by means of neural synchrony. This account relies on the neurophysiological properties of cells, and their ability to synchronize activity due to the rhythmic effects of ion conductances. A brain area that has been attributed with this property is the thalamus, which takes in sensory information from the neural periphery (i.e., sensory organs), and relays it to the cortex. In doing so, different perceptual cues are bound together due to the inherent physiological nature of the thalamic and thalamic relay cells; this can, in theory, explain how different perceptual cues are bound together into a unified representation (Singer and Gray, 1995). 
  
 Upon analysis of this claim, it seems as though the integration that might be attributed to the thalamus would be of the multi-modal variety, since within-modality integration could perhaps more easily be attributed to the cortical areas in which parallel features of a unimodal input would be integrated with each other (for example, the color, motion, line orientation areas of the cortex, with respect to visual input). Since the thalamus receives driver input from many different peripheral sources, it would seem appropriate that the integration mechanisms associated with thalamic activation would be of the multi-modal variety. ​ Upon analysis of this claim, it seems as though the integration that might be attributed to the thalamus would be of the multi-modal variety, since within-modality integration could perhaps more easily be attributed to the cortical areas in which parallel features of a unimodal input would be integrated with each other (for example, the color, motion, line orientation areas of the cortex, with respect to visual input). Since the thalamus receives driver input from many different peripheral sources, it would seem appropriate that the integration mechanisms associated with thalamic activation would be of the multi-modal variety. ​
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 ===How should we deal with these opposing theories?​=== ===How should we deal with these opposing theories?​===
  
- The theory posited by Treisman referring to feature binding as a result of spatially selective attention, requires that the concept of "​attention"​ is a well-defined one. The concept of “attention”,​ however, cannot be attributed to certain neurological facts, since “attention” itself is somewhat of an abstract theory. In this sense, Treisman’s feature binding theory is a good one insomuch as it gives a theoretical framework in which to fit data, thereby setting experimental data in a significant direction. However, since theories are somewhat flexible in the sense that data can be differently interpreted to be consistent with the theory, in order for a theory to be good it must be able to be disproved by specific characteristics of the data. Since “attention” itself is an abstractly defined term, it might be the case that it would be very difficult to disprove a theory whose central element was attention. However, the notion of expanding and shrinking receptive fields of visual neurons was referred to by Treisman (1998), and could serve as the concrete definition of “attention”,​ thus making the theory more disprovable and therefore valid. A major problem with theories as a guideline for validity of empirical data is that since there is so much experimental data to explain, differing theories can claim to explain //different aspects// of the data.+The theory posited by Treisman referring to feature binding as a result of spatially selective attention, requires that the concept of "​attention"​ is a well-defined one. The concept of “attention”,​ however, cannot be attributed to certain neurological facts, since “attention” itself is somewhat of an abstract theory. In this sense, Treisman’s feature binding theory is a good one insomuch as it gives a theoretical framework in which to fit data, thereby setting experimental data in a significant direction. However, since theories are somewhat flexible in the sense that data can be differently interpreted to be consistent with the theory, in order for a theory to be good it must be able to be disproved by specific characteristics of the data. Since “attention” itself is an abstractly defined term, it might be the case that it would be very difficult to disprove a theory whose central element was attention. However, the notion of expanding and shrinking receptive fields of visual neurons was referred to by Treisman (1998), and could serve as the concrete definition of “attention”,​ thus making the theory more disprovable and therefore valid. A major problem with theories as a guideline for validity of empirical data is that since there is so much experimental data to explain, differing theories can claim to explain //different aspects// of the data.
  
- For example, a supposedly contrasting theory to Treisman’s feature binding is the aforementioned temporal correlation hypothesis, in which features are bound together in an object representation due to the synchronous firing of specific groups of neurons (Singer & Gray, 1995). ​ However, Treisman (1998) claims that the temporal correlation hypothesis does not provide answers to the same binding problem that her theory tries to tackle. Treisman (1998) claims that neural synchrony can explain how features remain bound, but does not explain how they are originally bound together. ​+For example, a supposedly contrasting theory to Treisman’s feature binding is the aforementioned temporal correlation hypothesis, in which features are bound together in an object representation due to the synchronous firing of specific groups of neurons (Singer & Gray, 1995). ​ However, Treisman (1998) claims that the temporal correlation hypothesis does not provide answers to the same binding problem that her theory tries to tackle. Treisman (1998) claims that neural synchrony can explain how features remain bound, but does not explain how they are originally bound together. ​
  
 Thus it is clear that the binding problem is not only a real one, but a problem that has many different facets that are able to be explained by both psychological and neurological data. Thus it is clear that the binding problem is not only a real one, but a problem that has many different facets that are able to be explained by both psychological and neurological data.