SPRING Attention Flashcards
what is attention
no absolute certainty of what it is
measures alertness and arousal on a continuum
implies withdrawal from something to engage effectively with others
types of attention
alertness and arousal
vigilance
selective attention
describe alterness and arousal
extract certain info from enviorn or select a specific response
continuum of consciousness
ie coma - full alert
describe vigilance
sustained alertness to a specific stimulus/event despite enviornmental stimuli
describe selective attention
ability to scan event/stimuli and notice those that are relevant
filter stimuli to focus on those that relate to current goals and needs
limited processing of unattended info
why is selective attention needed
brain is limited resource - need to filter irrelevant info and preferentially process those relevant to current goal/survival for enhanced processing
what is hemispatial neglect
in inattention to the contralateral to the lesion
not due to primary sensory or motor deficit
not hemianopia
80% RHD and 40% permanent damage
82% more likely following RHD>LHD
may have comorbidity with other visual and motor impairments BUT not a result of motor or sensory deficit ie hemianopia
how is hemispatial neglect cause
chatteree 2003
damage to right/left hemisphere often due to stroke
deprives inferior parietal lobule and superior temporal gyrus to middle cerebellar artery that results in contralesional inattention
main characteristics of hemispatial neglect
anosognosia (so dont develop compensatory strategies)
cant orient to contralesional side
dont notice people on contralesional side
lower quality of life
behavioural deficits are dependent on severity of damage to certain areas of the brain
object copying in hemispatial neglect
patients find difficult to copy whole image
miss details contralesional to damage
clock - still draw full circle as represented in motor memotry/procedural
describe Bisiach and Luzzatti 1978 hemispatial neglect
milan residents
describe plaza del duomo from two perspectives
not problem of memory or vision
neglect contralesional side despite recollection from an alternative perspective
inattention is an internal problem of representation
describe corbetta and shulman 2011 hemispatial neglect
probability of reporing an obect to contralesional side is dependent on the no of distractors (cancellation tasks) and the level of meaning (drawing tasks)
ie prefer house not on fire but report that both houses look the same
spotlight metaphor of attention
posner 1978
focus on main stimuli and ignore surrounding
pay attention to a specific sensory channel - increase energy of said stimulus ie perception of brightness
describe the posner cuing task
fixate centrally then presented with cue to left or right that directs attention towards that area
valid cue: target follows same side as cue (100%)
invalid cue: target may or may not follow cue (50%)
null cue: no target following cue
describe posner 1980
posner cuing task
predictive cue directs attention covertly
RT inrease when follow cue location but decrease when invalid
improvement in atention for valid is because attention already allocated towards spatial location whreas invalid requires shift in attention to opposite side
describe bartolomeo and chockron 2002 hemispatial neglect on posner
does predictive cue direct attention to left and help orientation
YES - can detect stimuli in the left visual field almost as quickly asfor the right
BUT - difficulty orienting to left and disengaging attention from the ipsilateral side when the cue is invalid
what ERP waves link to attention
when attend to stimulus VEP waves (visually evoked potentials) and N1 P1 and P2 increase in response early processing of attended stimulus = increase p1n1 but ignored still being processed
define spatial attention
the process by which objects in certain spatial
locations are selected for processing over objects in other spatial locations
hillyard et al 1998 ERP and attention
Directing attention to the location of a stimulus results in amplitude enhancement of the P1 and N1 with little/no change in component latencies or scalp distributions- spatial attention exerts gain control or selective amplification of sensory information flow in the visual pathways between 80 and 200 ms after stimulus onset
Stimuli at attended locations elicit larger P1/N1 than unattended `
driver et al 2002 attending to spatial or feature
If attention could only select space, neglect patients should be able to identify the figure in the right picture but not in the left
But they can!
Neglect impairs spatial attention only, and shows that attention can select at the object/featural level
Anllo Vento and Hillyard 1996 Feature vs spatial VEP
VEP wave activity manipulating spatial and feature
- fixate on cross and different coloured targets - measure response to appearance of stimulus varying in colour (blue.red) motion(horiz.vertical) or spatial location
told to attend to spatial location and feature and only respond when they corresponded
- if dissociate the two then show diff VEP response
anllo vento and hillyard 1996 feature vs spatial VEPs results
found a boost in VEP response to spatial location
but not to feature ie colour/motion (p1n1)
selection negativity:
VEP that was increased when the attended feature appeared in the attended location
selection negativity (sn) increase when attended but not unattended feature appear - enhanced processing of the critical feature, rather than indiscriminate amplification that results from spatial attention
- enhanced processing of specific features despite amplification from spatial location
mechanism for attentional boost - multiplicative gain
attention increases response gain by multiplying the response by a factor
therefore - when attend to a stimulus, attention doubled compared to baseline
mechanism for attentional boost - additive gain
attention adds to the signal increase of responding to the stimulus the same as it would for baseline - creates a baseline shift
describe kastner et al 1999 additive attentional gain theory
attend: count no times pre specified image appear
expectation: prior to attention, covertly attend to location when stimulus will appear
unattend: ignore stimuli
BL: no stimuli
critical condition: EXP vs BL
look at v1 - v4 & TEO - areas in brain visual pathway that process visually presented information
results kastner et al 1999 additive attentional gain theory
unattend vs baseline: regions respond to stimuli without specific manipulation of attention
exp vs BL: pre attention vs no attention: same area activation but more in exp (no stimuli actually presented)
- attention selects from external world for further procesing - additive gain
what does the research overall show on the mechanisms of attention
neglect - disorder in the ability to disengage and redirect attention from the ipselesional to the contralesional side of space
objec and spatial attention increase neuronal response when stimulus appear AND shifts baseline activity in preperation for a stimulus
describe moran and desimone 1985 neuronal response to stimuli
HOW does attention filted desired from undesired stimuli
single cell recording of visual cortex (v4) in monkeys
trained to attend covertly to stimuli in one location and ignore others (match to sample task)