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PSYB65 chapter 11.docx

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Ted Petit

Chapter 11 - William James describes attention as o Selective attention: selection of inputs, thoughts or actions, while others are ignored o Voluntary attention: intentionally shift attention from one input to another o Reflexive attention: shift occurs in response to external event - Hermann von Helmholtz: o Demonstrated voluntary kind of intention even without eye movements and without changes of accommodation , one can concentrate attention on peripheral nervous system and exclude attention from all other parts o Eg. Stare at the middle of the screen but focus peripherals to corner of the screen. Able to remember letters from the corner of the screen - Cherry: o Cocktail party effect: focus listening to one single speaker among conversations and background noises o Found that people can extract information from attended ear but can’t recall information from other ear o Because of spatial hearing – tactics could ease task of filtering different voices (like air traffic controllers). Using voices with different pitch, speeds,tones, directions, accent, etc - Recent experiments say spatial hearing is not major cue. - Auditory selective attention is mediated by contralateral anterior temporal lobe o Those who had anterior temporal lobectomy impaired at task when it was on side opposite to their lesion in brain - How do we shift attention? Is attention mechanism distinct from sensorimotor systems? Early vs. Late selection - William James suggested attention is early in sensory processing chain. When attention to region was before light, but not if it was after flash. - Early selection: encoding and perceptual analysis of an input need not be complete before it is selected or rejected from further processing - If selection is this early, attention could modulate perceptions by influencing sensory events - Also evidence for covert changes that are low or early. Eg. Cochlea shows different activation under different attentional conditions but identical stimulus - Inner ear function seems to be more vulnerable to higher perceptual and attentional processes - Interpreting results of these experiences not straightforward. Better to refrain using accuracy or reaction time measures because attention could be exerting its effects late in perceptual process - Attention is possibly as early as primary auditory cortex. - Visual attention however may operate later in the visual system than in auditory. - Tactile attention is both early and late based on findings - Late selection: operates after sensory information has been perceived, identified and categorized - Evidence in late selection include stroop effect and study where people were conditioned to associate city names with electrical shock o In stroop task, nonattended stimuli can have semantic effects. o And participants can be conditioned to produce autonomic responses when they recognize city names and associate it to electrical shock. However, words were presented to unattended ear. o Therefore there is semantic knowledge of information in the neglected field, but they fail to explicitly attend to these stimuli How does attention shift? - Voluntary shifts o Experiment with valid trials (trials consistent to cued location) and invalid trials (when target appears in location other than what was cued). And there aer also cues that don’t give information about possibly location of target is neutral o When there are more valid than invalid trials, participants learn to use cue to ehlp anticipate location of target o Benefit : reduction in average reaction time o Cost: When invalid cues increase average reaction time o Early selection theorists claim shift in covert attention influenced perceptual processing o Late selection theorists might argue that the response required in the task was influenced by attention at a later stage of processing - Reflexive shifts in attention o Usually adaptive o Right frontal lobe responsible for reflexive shifts o Not always useful – attention deficit disorder leads to abnormal behaviour o When ccues are randomly presented and participant asked to ignore them, leads to Exogenous cueing: produces costs and benefits. Both effects are possible for valid cues, depending on the timing. - 50-200ms leads to benefit. - If valid flash is 300+ms, then it’s a cost/inhibitory after effect or inhibition of return. o Leading 2 possibilities - Reflexive orienting responses are normally very short, on the order of 200 or fewer milliseconds. Longer ones potentially be more life-0threatening.  Eg. Passenger sneeze while you’re driving, thats a short cue. But if it was long, it’d be life threatening, you’d swerve the car. - Cues tend not to provide valid information so there is reluctance to respond. Takes much of the 200-300ms after presentation of cue for people to recognize that something other than target and decide to act on its presentation. Neural systems sub-serving attention - Phrenologists say it’s at the back - But past 30 years have demonstrated practically every cortical cell can have its activity influenced by attention - Attention not strictly controlled by cortical structures - In Baddeley’s model of working memory, the central executive is the single system that controls attention. However there has been less research on central executive than the 2 slave systems (phonological loop and visuospatial sketchpad). Difficult to study without looking at the other 2. - Reported that central executive result in activation of dorsolateral prefrontal cortex - In nonhuman primates, also found activation of subcortical structures and more posterior regions of brain including parietal cortex - Posner and Peterson’s model involves 3 visual attentional mechanisms. o Posterior attentional system (PAS)- orients spatial attention, object search and inspection of object once found. Like a zoom lens. - Inputs is dorsal (how and where). Role is ventral (what). - Includes pulvinar nucleus of thalamus, superior colliculus, secondary visual areas, inferior temporal lobe and posterior parietal lobe o Anterior attentional system (AAS) - Working memory and executive control system that subserves conscious control of attention - Includes cingulated gyrus and frontal cortex and contains many connections to structures with mnemonic functions such as hippocampus, amygdale, and medial temporal cortex o Vigilance system (VS) - Prepare and sustain alertness toward signals that demand high priority - Lateralized. Right frontal damage compromises tha ability to develop and maintain an alert state or perform vigilance atsks. Left hemisphere damage does not produce same behavioural deficits - Dependent on norepinephrine dependent neurons Studying Consciousness - Term consciousness hard to define - Lucid dreaming: be aware of yourself during dream or realize you are dreaming. o Are they considered conscious? - Drunk person, can’t remember after. Were they conscious? Defining consciousness - Conscious and unconscious as a dichotomy is an oversimplification - Consciousness includes selective attention, explicit memory, language and self-awareness - Bisiach’s definition: three different senses of consciousness o Nonphysical entities (soul or immaterial mind) o Sensation, thought or action o Monitoring internal representation - But fails to mention awareness - Niedermeyer identifies same components and includes selective attentiveness, changes in mental states and vigilance - Damasio define consciousness as o Core consciousness: transient process when organism interacts with object o Extended consciousness: more complicated. Gradual build-up of autobiographical self, requires long term memory. Enhanced by language but language not necessary - Helpful to see consciousness as either a state or trait. Human can exhibit trait but not always be in conscious state. Whereas some organisms cant exhibit the state of consciousness therefore can’t exhibit the trait either The neural basis of consciousness - Farah proposes 3 theoretical perspectives of consciousness o Consider consciousness as privileged role of particular neural stru
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