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42 Cards in this Set
- Front
- Back
Selective attention |
We need to filter out irrelevant information and selectively attend to relevant information. Typically we shift our attention from one object to another by moving our eyes. Fovea as the focus of attention. Eye gaze as a social cue. |
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Fixations |
Keeping the eye fixed on a specific location for a period of time. |
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Saccades |
rapid jerky eye movements from one location to another |
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Salience |
Characterisitics that stand out in the scene. Physical properties such as colour, brightness, contrast, orientation, abrupt onset, cause reflexive shifts of attention. Relies on bottom up and top down processing. |
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Reflexive attention |
Automatic, effortless, bottom up, rapid. |
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Voluntary attention |
Controlled, requires effort, top down, slow. |
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Visual search |
Looking for a specific item among distractors. Some features are critical and grab attention automatically. Pop out search. Serial search. |
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Pop out search |
Reaction time does not change with the number of distractors. |
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Serial search |
Reaction time increases with the number of distractors. |
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What determines where we look |
Knowledge about the scene, goals of the observer. |
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Reddy et al. experiment |
Used a dual task paradigm to measure the link between focused attention and perception. central task, peripheral task, dual task. Participants performed well in single task conditions. In dual task conditions participants were better at discriminating between faces compared to letters. |
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Inattentional Blindness |
Mack and Rock asked participants to indicate whether the horizontal or vertical portion of a cross was longer from trial to trial. In some trials an additional object was presented and many failed to notice it. |
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Attention and change detection |
One of the most important functions that attention serves is to detect changes in the environment. Sudden changes result in motion transients that trigger reflexive shifts of attention. If these motion transients are masked it has a dramatic influence on change detection. |
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Attention vs. eye movements |
Subjects can attend to different spatial locations without making eye movements. Premotor theory. |
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Covert visual attention |
If a participant is cued to attend to a specific location they are faster to respond compared to an uncued location. cues do not need to be informative. |
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Inhibition of return (Posner and Cohen) |
When attention is reflexively drawn to a peripheral location, perception is facilitated at that location for a short time. Shortly afterwards, processing at the same location is slowed. |
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Attention within vs. Between objects |
Does attention focus on a specific location, or can it spread to an entire object? Cue appeared in the upper or lower portion of one object. Target appeared either in the same location, within the same object, or in the uncued object. |
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Effects of attention on perception (Carrasco et al.) |
Used a cuing paradigm to investigate the link between attention and perception. The cue is presented, two gratings are presented simultaneously (different orientations), report the orientation of the grating that was of higher contrast. When the gratings were of equal contrast, participants selected the one that was in the position of the cue. |
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Binding |
Process by which features such as colour, form, motion, texture etc. are bound together to create the perception of a coherent object. |
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Feature integration theory |
Proposes that binding occurs in two stages. Pre-attentive stage and focused attention stage. Activation in the ventral stream would process information about form, colour, etc. Activation in the dorsal stream would process information about location, motion. |
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Pre-attentive stage |
Object is broken down into constituent features by the visual system (does not require attention) |
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Focused attention stage |
Features are recombined to perceive an entire coherent object |
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Illusory conjunctions |
Occur when features of one object become incorrectly associated with another object. Present images for 200ms followed by a mask. Participants reported illusory conjunctions on 18% of trials |
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Neural synchrony and binding |
Neurons in different parts of the brain are responding to the same object may fire synchronously. |
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Physiology of attention |
SPL, IPL, IPS, LIP |
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SPL |
superior parietal lobe |
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IPL |
Inferior parietal lobe |
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IPS |
Intraparietal sulcus |
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LIP |
Lateral intraparietal sulcus |
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Attention signals in area LIP (Colby et al.) |
Recorded from neurons in monkey parietal area LIP when the monkey was not attending, or attending to a peripheral stimulus in its receptive field. |
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Salience maps in area LIP |
Neurons in LIP respond best to stimuli that suddenly appear in the neurons receptive field. |
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The biased competition model |
Neurons can bias attention towards stimuli at a specific spatial location. Baseline activity of ventral stream neurons is increased when the attended location is within the neurons receptive field. |
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Cognitive neuroscience of attention |
Activity in many brain regions are modulated by attention. A great deal of evidence implicates the parietal cortex is the source of control signals. |
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Dorsal attention network |
Allocation of attention to a specific location in space. Superior parietal lobule. |
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Ventral attention network |
Interrupts the current focus of attention in order to reorient to new stimuli. Right hemisphere. Inferior parietal lobule. |
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Balint's Syndrome |
Due to bilateral lesions of occipital-parietal cortex. 3 main symptoms: optic ataxia, ocular apraxia, Simultanagnosia. |
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Optic ataxia |
Problems with visually guided action |
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Ocular apraxia |
Difficulty fixating, scanning, and initiating eye movements. Neglect of left space. |
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Simultanagnosia |
Inability to perceive more than one object at a time. Attentions can be space based or object based. Can perceive objects correctly but only attend to one at a time. Attentional 'tunnel vision'. |
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The right IPL and spatial neglect |
The inability to respond or attend to stimuli in contralesional space. Behave as if the left half of the world ceases to exist. Cannot be due to a primary sensory or motor deficit. |
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Neglect and sensory extinction |
Extinction task: two stimuli presented simultaneously to the left and right of the patients midline (left target typically extinguished). Rightward attentional bias. However, neglect and extinction are dissociable. |
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Representational neglect |
Neglect is not a disorder of vision or memory. Even when asked to imagine scenes the patient neglects the left, and this is viewpoint dependent. |