Term
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Definition
| Agnosia is disorder involving failure of perception. |
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Term
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Definition
| Visual agnosia is limited to the visual modality. |
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Term
| Two major fiber bundles (fasculi) which comprise most of the output from the occipital lobe. |
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Definition
1. the superior longitudinal fasciculus
2. the inferior longitudinal faciculus |
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Term
| Two cortical pathways for visual perception |
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Definition
1. dorsal or occipito-temporal pathway
2. ventral or occipito-temporal pathway |
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Term
| dorsal or occipito-temporal pathway |
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Definition
| The "where" pathway. Specialized for spatial perception, for determining where an object is, and for analysing the spatial configuration between objects. |
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Term
| ventral or occipito-temporal pathway |
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Definition
| The "what" pathway. Specialized for object perception and recognition, for determining what it is we are looking at. |
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Term
| What area should you lesion if you want to disrupt the "what" pathway? |
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Definition
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Term
| What area is central to spatial attention? |
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Definition
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Term
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Definition
| Impaired face perception. Lesions fall along the ventral pathway. |
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Term
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Definition
| Difficulty naming objects. |
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Term
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Definition
| Patients with optic ataxia can recognize objects, but they cannot use visual information to guide their actions. Associated with lesions of the parietal cortex. |
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Term
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Definition
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Term
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Definition
| The ability to recognize an object in countless situations. |
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Term
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Definition
| In a view-dependant theory, perception is assumed to depend on recognizing an object from a certain viewpoint. Posits that we simply need to match a stimulus to a represtntation stored in memory. |
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Term
| view-invarient frame of reference |
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Definition
| Recognition depends on an inferential process based on a few salient features. Sensory input defines the basic properties; the object's other properties are defined with respect to these properties. |
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Term
| What is blindsight and why is it interesting? |
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Definition
| Blindsight is the residual ability to localize stimuli following cortical blindness (the ability to attend to objects one is not aware of). It is interesting because those with blindsight respond to stimuli as if they can see. |
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Term
| Describe an experiment used to describe the "what" and "where" pathways. |
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Definition
| A double dissociation involving a landmark task and an object discrimination task. In the landmark task, food is placed in a well next to a cylinder. After the association is learned, the rule is reversed so that the food is placed in the well farthest from the cylinder. The monkey, although initially confused, eventually learns the new rule. Monkeys with temporal lobe lesions (lesions in the “what” pathway) also show eventual improvement in the reversal, however monkeys with parietal lobe lesions (“where” pathway) lesions fail to improve. In the object discrimination task, the monkey must associate food with an object. Beside each food well is an object, either a cylinder or a cube. The monkey must learn that the food is associated with the cube; whenever the cube moves to the other food well, the food move with it. The monkeys with temporal lobe lesions failed to make the connection |
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Term
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Definition
| Refers to the idea that cells can signal the presence of a known stimulus. |
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Term
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Definition
| inability to recognize objects due to perceptual problems. |
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Term
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Definition
| failure of visual object recognition not due to perceptual problems. |
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Term
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Definition
| a form of acquired dyslexia |
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Term
| Give a theoretical example of how all objects may be decomposed into a finite set of parts. |
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Definition
| Irv Binderman’s geon theory posits that a finite set of shapes called geons, or geometric ions, comprise the perceptual alphabet for constructing object objects. Any object can be decomposed into its constituent geons. Geons are the fundamental building blocks for object recognition. |
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Term
| Marr's theory of object recognition |
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Definition
| A view-invarient theme which posits that a critical property for recognition is establishing the major and minor axes for object recognition. These properties will hold across different vantage points. |
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