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Cognition Quiz 2 (2).docx

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PSYC 3260
Norman Park

Chapter 3- Attention  Attention- process that enhances some info for further processing and inhibits other info to set aside  William James o Attention is the taking possession by the mind, in clear and vivid form, of one of what seem several simultaneously possible objects or trains of thought o Focalization, concentration, of consciousness are of its essence o Selection/consciousness is an important aspect of attention o There is conscious attention and other processes that occur without conscious attention  Types of attention: o Selective attention- people are limited in their capacity to process incoming info, therefore need to be able to focus on info that is relevant to their goals  Can be selective in space (processing info in one location may cause you to miss other info) or time (when new info is rapidly presented, processing some of it may cause you to miss other info)  Attention seems to be guided by top-down processing  Exogenous attention- salient external stimulus that drives attention (bottom-up)  Endogenous attention- covert, internally controlled, driven by goals (top-down) o Sustained attention- takes place over a prolonged period of time, so that you keep in mind the goal you’re attempting to achieve  Losing sustained attention- lose focus and get diverted to an irrelevant task o Divided attention- doing 2 activities at the same time  Sometimes it is functional to process two different streams of info  Automaticity o Posner and Snyder- a skill is automatic when it occurs without intention, doesn’t give rise to conscious awareness, and doesn’t interfere with other mental activities o Stroop effect- most people cannot avoid reading the words, so it appears that reading the words occurs automatically  Difficult because meaning of the word and colour of the word are inconsistent  we cannot ignore the meaning of the word o Shiffrin and Schneider- effects of practice on memory search task  RT increases with study list size, however, with practice RT becomes stable o Logan- as a task becomes practiced, the correct outcome becomes represented in memory and the task cues the memory and the outcome is retrieved and produced  Posner and Boies- attention has three components o Orienting to sensory events o Detecting signals for focused processing o Maintaining an alert state  Failures of selection in space- not being able to notice all the info simultaneously present to you at once o Change blindness- failure to detect changes in the physical aspects of a scene o Experiment: Simons and Levin stopped pedestrians to ask for directions, two people carrying a door walked between them, experimenter switched with a second experimenter to continue the conversation, only half the pedestrians noticed the change of speaker o Change deafness- miss changes between voices in an auditory scene o We select partial info from the world around us and are not very attentive to the rest o Top-down processing- knowledge, beliefs, goals, and expectations can alter the speed and accuracy of the processes that select meaningful or desired info (highly adaptive) o Bottom-up processing- sensory event gets your attention o Focused attention- concentration on one source of input to the exclusion of any other o Divided attention- more than one source is attended and the info selected is imperfect, may be that two sources of info compete for limited attentional resources o Change deafness- miss the changed between voices in an auditory scene  Failures of selection in time- processing new info will cause you to miss other incoming info o Studies: participants shown a stream of letters, one of them white (T1) and the rest of the black o In some of the trials, a second target (T2, probe) included in the stream of letters at various intervals following the appearance of the white letter o First part of experiment- ignore T1 and indicate whether or not T2 was present in the sequence of letters (single-task) o Second part of experiment- asked to report the presence of T2 and to identify T1 whenever it appeared (dual-task) o In the single-task condition, participants did well at detecting T2 regardless of how long after T1 it appeared o In the dual-task condition, they failed to report T2 when it appeared 100 and 500 milliseconds after the appearance of T1, but after greater delays, they were able to spot T2 again o Attentional blink- short period during which incoming info is not registered after an earlier stimulus is presented o Repetition blindness- failure to detect the later appearance of a stimulus when the stimuli are presented in a rapid sequence o It is believed that the failure to encode the second stimulus occurs because it is not individuated or selected as a distinct event when it rapidly follows the first and only one event is registered  Limitations o Bottleneck- restriction o the amount of info that can be processed at once, certain mental operations have to be carried out sequentially o Dual-task interference- performance is lower when you have to attend to two separate sources of visual info or two separate visual events o Response bottleneck- interference that arises when trying to select between two possible responses to even a sole sensory stimulus (slowing down actions)  Endogenous attention- attentional process that is top-down, originates from within  Exogenous attention- bottom-up fashion and by stimuli generated outside oneself  Covert attention- although the eyes may be directed at a specific spot, visual attention can be directed elsewhere covertly o Study: two boxes appear on a computer screen, one to the right and one to the left of a central fixation point, endogenous cue (arrow) leads the participants to focus attention to that location even while their eyes are kept on a fixation point  Valid trials- target is subsequently presented at the cued location and participants press a response key as soon as they detect it  Invalid trials- arrow cue appears pointing in opposite direction of target  Neutral trials- target appears at same location but arrow is not informative (points left and right) o Two main results:  Participants detected the target faster and more accurately in the valid condition than neutral condition (suggests that attending to a location can facilitate processing in that location, even without eye movements)  Participants detected the target in the invalidly cued location significantly more slowly than in the neutral and valid conditions (they were deceived or misled by the cue) o Same results with exogenous cues with one difference, attention can be rapidly and automatically drawn toward the salient cue with no extra processing time (with arrow, processing time was required to see what it meant)  For the same task, patients with hemispatial neglect (lesions to right parietal lobe) detected the valid targets normally on the right side and almost normally on the left side (neglected side) o For the invalid trials, when the cue occurred on or pointed to the left side but the target appeared on the right side, they detected the target more slowly than in the valid trials, but still in the normal range  Three separate mental operations- Posner constructed a model for attention due to this fact: o Disengaging of attention from current location o Moving attention to new location o Engaging attention in a new location to facilitate processing in that location  Patients with damage to the midbrain suffer from a disorder called progressive supranuclear palsy o Have no difficulty with disengage or engage operations o However they are slow in responding to cued targets in the direction in which they had difficulty orienting, suggesting a problem in moving attention to the cued location  Patients with lesions to the pulvinar (thalamus) were slow to detect the valid and invalid cues that appeared on the side of the space opposite to their lesion o Suggests that patients cannot engage attention on the affected side  Cross-modal links- directing attention to one side of space in one modality automatically results in attention to that location for other modalities as well (seeing the woman at the party made her voice more audible)  Object-based attention o When attention is directed toward an object, all the parts of that object are simultaneously selected for processing o An object and its associated parts and features are selected together o Our perceptual system can handle two judgments well when attention is focused on a single object o When attention is divided across two different objects, making two judgments becomes very difficult o Evidence from brain damage- no object-based neglect occurred, only space-based neglect o Balint’s syndrome- following bilateral damage to parietal-occipital region (simultagnosia)  Neglect entire object  Affects the selection of entire objects irrespective of where the objects appear in the display, and a whole object may be neglected even if it occupies the same spatial position as another object  This condition can be helped when info in the visual scene is bound together to make a single object  Broadbent- selection is made at an early stage of processing o Attentional system as containing a limited-capacity channel through which only a certain amount of info can pass o The bottleneck is immediately after the sensory store and only a small amount of info (mostly based on physical characteristics) passes through for further, semantic processing o Dichotic listening- played competing speech inputs into both ears of the participants o Participants had to shadow- follow and repeat as fast as possible one stream of speech input and ignore the other o Patients had no memory of what was played in the unattended ear, but they noticed whether the sex of the speaker was different or whether the speech became a pure tone o Early-selection bottleneck theory- unattended inputs are filtered out and attended signals are admitted through on the basis of their physical characteristics o Cocktail party effect- doesn’t support early-selection, if info is salient and important to participant, they could detect info the unattended channel even with no changes to its physical features  Spotlight theory o Spatial attention selectively brings info within a circumscribed region of space to awareness, and info outside that region is more likely to be ignored o The spotlight metaphor can break down because attention can be directed to a single object, even if superimposed on another object o More recent studies characterize attention as a dynamic process in which info selection is automatically accompanied by active inhibition of other info (competitive system)  Feature integration theory (FIT) o Concerned with the role attention plays in selecting and binding complex info o Disjunctive search trials- target differs from the distractors by a single feature, such as shape (easier), also preattentive o Conjunctive search trials- target is defined by a conjunction of features such as colour and shape o The perceptual system is divided into separate maps, each of which registers the presence of a different visual feature (colour, edges, shapes) o Each map contains info about the location of the features it represents o If you know you’re looking for an object defined by a shape, you need to only refer to the shape map o However conjunctive searches require the joint consultation of two maps, shape and colour o You can search faster for the presence of a feature than its absence o Illusory conjunctions- incorrect combinations of features o Even disjunctive search may require attention and the preattentive- attentive distinction between these forms of search may not hold o Guided search theory- output from a first stage of info processing guides later serial search mechanisms  ERP studies o Directing attention toward a stimulus results in an increase in the amplitude of the waveform as early as 70-90 milliseconds after the onset of the stimulus o Suggests that attention enhances the early processing of visual stimuli in the brain, which leads to better perceptual detection of the attended target stimulus o Exogenous, automatic attention and endogenous, voluntary attention have at least some underlying processes in common o Enlargement of early waveforms at the occipital cortex is consistent with the idea that selection occurs early in the processing system and that incoming sensory signals may be enhanced early as a result of attention o Not good at indicating exactly which region of the brain is responsible for generating the brain waves  Functional neuroimaging (PET) o Good complementary approach to ERP methods because of its spacial precision o Different neural systems are used when attention is directed to a location before the appearance of a stimulus and when an unexpected salient stimulus appears and redirects the participant’s attention o In the endogenous cases, a network of frontal and dorsal parietal areas was involved o In the exogenous cases, the ventral system that included the temporal parietal junction and ventral frontal cortex were activated o The two systems are functionally independent but interactive  TMS o Confirmed the critical role of parietal cortex in attention o TMS applied to right parietal cortex led them to requ
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