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Canada (158,081)
Psychology (9,549)
PSYB57H3 (369)
Dwayne Pare (122)
Chapter 4


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University of Toronto Scarborough
Dwayne Pare

CH.4 PAYING ATTENTION Selective Attention Dichotic Listening  Participants were instructed to pay attention to one of these inputs- the attended channel and the other is the unattended channel  To make sure participants were paying attention, they were usually given a task called shadowing. The attended channel contained a recording of someone speaking and participants listened to this speech and had to repeat it back.  Unattended speech could only be detected by a few participants Some Unattended Inputs are detected  Cocktail party effect where things with personal importance are noticed, even though rest of the unattended channel is perceived only as an undifferentiated blur Perceiving and Limits on Cognitive Capacity  Filters are erected from potential distractors. Desired information (attended channel) is not filtered out and so goes on to receive further processing. Filtering is rather specific and is done on a distractor by distractor basis- as if entry lacked the broad ability to separate desirable guests in general from undesirable ones.  Sentry seems to have assignment of blocking specific, already identified gate crashers. You inhibit your response so this distractor and do the same for that distractor but efforts are of little value if some new, unexpected distractor comes along and will need to develop a new skill aimed specifically at blocking the new intruder  We block processing of distractors and promote processing of desired stimuli In-attentional Blindness  Participants were instructed to point their eyes at the dot and to make judgements about the cross shown just off to the side. The dot briefly changed to another shape. If participants were not warned about this (not paying attention to the dot), they routinely failed to detect this change- even though they had been pointing their eyes right at the dot the whole time. If participants were warded (alert for possible changes), then virtually they detected the change  Participants not expecting any shapes to appear and were not prepared for these shapes is called by Mack and Rock as in-attentional blindness Conscious Perception, Unconscious Perception  Mack and Rock argue that there is no perception without attention. There is no conscious perception without attention Change Blindness  It is observers’ inability to detect changes in scenes they’re looking at directly.  Having a stimulus directly in front of yur eyes is no guarantee that you will perceive the stimulus Early vs. Late Selection  Studies may reveal genuine limits on perception so that participants literally don’t see stimuli or these studies may reveal limits on memory so that people do see the stimuli but immediately forget what they’ve just seen  Early selection hypothesis, the attended input is identified and privileged from the start, so that the unattended input receives little analysis  Late selection hypothesis, however, all inputs receive relatively complete analysis and selection is done after all of this analysis is finished  Late selection- selection done after distractors were perceived but before they made it to consciousness. Early detectors- stimuli receiving little analysis and indeed falling out of the stream of processing at a very early stage.  Some data indicates late selection and other on nature of attended input. If input is complex then more effort needed and little effort will be left for other stimuli, with the consequence that the other stimuli receive less processing, leading to a data pattern consistent with early selection. If attended input is simple, processing will demand few resources leaving more room for unattended input Selective Priming  Priming is produced by your visual experience whether each detector has been used recently/frequently in the past. Priming can also come from another source: your expectations about what the stimulus would be  Participants don’t notice shapes in inattentional blindness because they don’t expect any stimulus to appear so they have n reason to prepare for any stimulus. The stimulus, when it’s presented, falls on unprepared detectors. The detectors don’t respond to stimulus and you end up not perceiving the stimulus  Prior exposure can activate detectors for things like your name, you don’t need to prime and detectors will fire even if your attention is elsewhere Two Types of Priming  Perception require primed detectors and priming can come from 2 different sources  Sometimes priming is a simple matter of the stimuli you encountered in past (recently or frequently) and you don’t need to take effort or require any resources  You can deliberate prime detectors for inputs you think are upcoming, so that you’re ready for those inputs when they arrive. You don’t do this priming for inputs you have no interest in and you can’t do this priming for inputs you can’t anticipate. This priming is under your control  Posner and Snyder study with letters to see if its different or same with warning signals. In this task accuracy rates were high but speed of responding varies condition to condition. Posner and Snyder compared response times in the primed and neutral conditions, we can ask what benefit there is from the prime.  Expected to have faster RTs in the primed condition than in neutral conditions because of the prime, relevant detectors have just fired s detectors should still be warmed up. When target stimuli arrive, detectors should fire more readily, allowing a faster response.  Table 4.1  RTS were faster in the primed condition than in the neutral condition. Detectors can be primed by mere exposure to a stimulus. priming is observed even in the absence of expectations which is stimulus based  Mislead participants had no effect. Performance same for neutral condition. Priming the wrong detector, it seems, takes nothing away from the other detectors including detectors actually needed for that trial. Priming one detector influences the functioning of that specific detector but neither helps nor hinders the other detectors  High validity primes have another influence; they’re excellent predictors of the stimulus to come. They will produce a warm-up effect and also an expectation effect whereas low validity primes produce only the warm-up Explaining the Costs and Benefits  One type is stimulus based produced just by presenting a priming stimulus with no role for expectations  The other is expectation based and is created only when participant believes the prime allows a prediction of what’s to come.  Expectation based priming takes longer to kick in than stimulus based priming because you need a moment to form an expectation and a bit longer to activate relevant detectors. Stimulus based priming can be observed immediately after the prime; priming based on expectations takes roughly a half-second to develop  2 types of priming can also be distinguished in terms of their cost. Stimulus based priming appears to be free and you can prime one detector without taking anything away from the other detectors. In the low validity condition, misled trials lead to responses just as fast as those in neutral trials  Expectation based priming has a cost. With high validity primes, responses in misled condtn were slower than responses in neutral conditions (misleading participants hurt their performance)  Expectation based priming, by virtue of revealing costs when mislead, reveals presences of a limited capacity system. Perceiving involves some work and this work requires some limited mental resources. Chronometric Studies and Spatial Attention  spatial attention is the ability to focus on a particular position in space, and thus to be beter prepared for any stimulus that appears in that position  in the Posner et al. study, participants had to press a button as soon as they saw the target. If participants knew where target would appear, they were slightly faster (although procedure prevented them from moving eyes to this target location). If, however, participants were misled about the target’s position, their responses were slower than they were when participants had no expectations at all. Attention as a Spotlight  “Beam” marks the regions of space for which you are prepared so inputs within the beam are processed more efficiently. The beam can be wide or narrowly focused, something that can be demonstrated formally in the lab or informally and it can be moved as you explore (attend to) one aspect of the visual field or another  Attention occurs prior to any eye movement as eye movements are slow, requiring 180 to 200 ms and withprimes 150 ms after stimulus is presented  Evidence suggests that ctrl of attention depends on a network of brain sites in the frontal cortex and parietal cortex. Neural connections from these areas send activity to other brain sites (like visual areas in occipital cortex)that do the actual analysis of the incoming information. Expectations (based on ur goals and info you received) are supported by one group of brain areas, and are used t modulate activity in other areas directly responsible for handling the input  Neural mechanisms are in place that allow you to adjust your sensitive to certain inputs, there is no spotlight beam. You only prime yourself and have stimuli for the ones you care about which increases sensitivity to the desired input which is what you want and the other ones you don’t care about fall on unprepared (unresponsive) detectors Attending to Objects or Attending to Positions  Beam may not line up with boundaring of the object you’re shining on.  We pay attention to object than to positions inspace. The target of our attention will just be the object we attend to  People with brain damage (in parietal cortex) produce extraordinary problems in paying attention. Patients with unilateral neglect s
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