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)
what does moran and desimone 1985 suggest
unwanted info is filtered from the receptive field of neurons in the extrastriate cortex as a result of selective attention
cell response is determined by the properties of attention
bottom up attention (exo)
employed automatically in response to salient stimuli
characteristics of a scene/stimulus salience reflects sensory stimulation
top down attention (endo)
voluntary attentional control based on knowledge, expectation, task or goals
internally generated attentino
describe de fockert et al 2004 exogenous attention
attentional capture - stimulus salience
manipulated the shape/colour/size of target and distractor singletons
1- target identified by diff shape and colour
2- target only diff shape
3- target diff shape but distractor diff colour(same shape)
4 - no change in colour but distractor smaller
de fockert et al 2004 exo attention results
presence/absence of salient coloured distractor singleton associ with increased attention in
left+right superior parietal lobe, left lateral precentral gyrus (assoc with frontal activation)
RT sig increase when colour distractor - longer to detect target
if exo and endo part of the same system
yantis 1998
Should demonstrate the same functional characteristics
May differ quantitatively (in magnitude or time-course), but not qualitatively
Modulate similar stages of processing
Should be implemented into the same brain circuits
if exo and endo diff system
klien 2009
Qualitative differences between them
Modulate different stages of processing
Evidence for a double dissociation
Should be implemented in brain circuits which may have overlap, but should contain exclusivity for each
describe kincade et al 2005 exo vs endo
pps focus on fixation cross -
exo: grid of on unique colour singleton then respond to presence of target - 50% predictive
neutral: grid of many colours and respond to target - to% predictive
endo: grid of many colours then fixation cross brightened into arrow indication cue for target - 75% predictive
behavioural results kincade et al 2005 exo vs endo
look at cue-target stimulus onset asynchronies (SOA) - either 150 or 700ms
exo: RT increase between 150 >700ms when target valid vs inalid (even though unpredictive)
endo: RT sig longer on invalid than valid trial - using spatial cue and cue more effective for long vs short SOA - greater benefit from cue when they have sufficient time to process it
neuro results kincade et al 2005 exo vs endo
dorsal and ventral frontoparietal regions
-Endogenous = larger preparatory activity in FEF and IPS (dorsal frontoparietal regions)
Exogenous = occipitotemporal regions and FEF
Partly overlapping but distinct
neural circuits
corbetta et al 2002
showed 2 distinct networks for endo vs. exo
When attention shifted - VENTRAL set of brain regions within the fronto-parietal network engaged (TPJ, VFC
When attention was sustained at a location/feature - DORSAL set of brain regions were engaged (FEF, IPS)
partially segregated but interact
research (corbetta et al) show that the dorsal attention network is in control of
top down, endogenous attentional control
research (corbetta et al) shwo that the ventral attention netwrk is in control of
bottom-up, exogenous attentional control
what is the primary means by which humans sample their environment (findlay and gilchrist 2003)
by saccadic eyemovements and fixations using occulomotor control
what areas in the brain contribute to occulomotor control
dorsal
FEF and lateral intraparietal area(LIP)
describe nobre et al 2000 covert vs overt visual attention
covert:
like posner - fixation cue for invalid/valid target
saccade task - target move left/right and must follow and fix
fmri results nobre et al 200 covert vs overt visual attention
areas for shiftting spatial attention via saccades activates overlapping neural circuits to that of covert - parietal and frontal regions
covert expectancy increases activation to occumomotor condition - attention engage sensorimotor areas independent of overt movement
premotor theory of attention
rizzolatti et al 1987
spatial attention and eyemovement are interdependent
attentional shifts can be performed independent of eye movements and vise versa
dorsal network and occulomotor of brain interact to shift focus
but covert - shift without eye movement
FEF and covert attention
part f frontoparietal network for attentional control
occulomotor control for planning and saccade execution
when stimulate - saccade contralateral to hemisphere
increase activity in attention w/o overt eye movements to location
describe moore and fallah 2004
microstimulation to FEF controls spotlight of attention - apply and saccade to location
monkeys to detect siming of target in specifi location and ignore distractors
prior to dimming - microstimulation in FEF to sbthreshold level (covert attention)
results moore and fallah 2004
microstimulation to target = increased ability to detect dimming target
do not need cue - stimulation allows direct shift of attention
FEF in control of where attention is directed
define overt attention
focus that coincides with sensory orientation ie gaze
define covert attention
focus independent of sensory orientation but remain alert to the sitmuli
behtmann et al 1997 hemispatial neglect
equal amount of saccadic eye movements across the visual field despite a sig bias towards right on line bisection
laduras paladine and cubeline 1998 hemispatial neglect priming
word on neglect side not reported but leads to fater response to words semantically related to it
heilman and van den abell 1980 hemispatial neglect EEG
trace alpha wave desynchronisation which reflects cortical stimulation
LEFT parietal lobe activate to stimuli on RIGHT hemispace
RIGHT parietal lobe exhibits equal distribution of activity across the visual field
what is representational neglect
neglect is not just manifest in attention to the external world but in internal representations of the world ie memory for it
types of hemispatial neglect tests
object copying/drawing from memory
line bisection
visual search task
describe line bisection HN
asked to bisect centre of line
tend to deviate towards the right
describe visual search task HN
cancel/idenfity targets within a visual display
may incorporate distractord ei letters, stars, digits, bells
stars most sensitive
neglect fail to identify targets to the left of the display
Marshall and halligan 1988 HN burning house
show two hoses - one burning to the left
HN patients chose right>left as say prefer but fail to report that one not chosen is burning
describe space based theories of attention
space is the primary unit for attentional selection
attention selects a region of space independent of the objects that they contain
ie spotlight metaphor (posner 1978)
what brain regions are thought to be involved in attention
temporoparietal junction
superior colliculus
pulvinar (thallamus)
FEF
TPJ in attention
disengages attention from current stimulus/orientation
superior colliculus in attention
determined the reflexive shifts towards bottom up stimuli
pulvinar/thallamus in attention
egages attention towards a spatial location
FEF in attention
voluntary attentional shift that may also act to inhibit the reflexive shifts in attention by the superior colliculus
describe object based models of attention
propose that grouping mechanisms divide the attentional field across stimuli
attentional selection is determined by the no objects in the visual field
neisser 1967 two stage process of object based attention
visual field pre attentively seperated into perceptual units according to gestalt processess ie based on similarity or proximity
once attention is directed, focal attention processess al features of an object regardless of spatial location
duncan 1984 evidence for object based theory of attention
observers given two overlapping objects with two attributes
- line (dotted or dashed) and box (large or small)
discrimination between the obects less accurate when report attributes of two diff objects than of two of the same objects
moran and desimone 1985 results
attend to effective or ineffective stimuli in task to determine if stimuli presented in the same or diff lcoation
effective and ineffective in receptive field : call respond strong to effective
multiple stimuli in receptive field : neuronal response determined by effetive stimuli
over half the usual response when ignore effective stimuli in receptive field
ineffective cue outside receptive field - no response
- attention atenuate processing of relevant > irrelevant stimuli
mangun and hillyard 1991 neural basis of spatial attention using ERPS
central cues direct towards of away from peripheral targets
detect or make choice discriminations about targets appeared in covertly attended/unattended locations
p1 > attended targets in both detection and discrimination
n1> oly for disciminaion of targets
spatial attention facilitates sensory gail control - enhance processing assoc with sensory signals in attend locaiton
jonides 1981 endo and exo control
test interdependent of endo and exo attention control
centrally presented directional cue - arrow at fix or peripherall presented locational cue - arrow at adjecent location
visual search in letter display - RT to central cues slowed when Wm task consume attention
cueing effect persistent when ignore peripheral>central
cueing effect modulated by relative proportion of central cues but not peripheral
bourgeois et al 2015 endo/exo
visual search paradigm using monetary rewards
one of two distractors assoc with high reward (80%) or low reward (20%)
peripheral cue either 80% predictive of target (endo) or 50% (exo)
distractors 25% of time
distractors with prev assoc high monetary reward increase attentional priority even though no loner relevant
- competitive shifts in attention
