L3 - attending and spatial brain Flashcards
space in the brain: different forms
- RETINOCENTRIC SPACE = location on sensory surfaces (e.g. retina)
- EGOCENTRIC SPACE = location of objects relative to the body
- ALLOCENTRIC SPACE = location of objects relative to each other
attention
- the process by whcih certain info is selected for further processing and other information is discarded.
spotlight metaphor of attention
- visual search : spotlight may move from one spatial location to another.
- may zoom in or out (narrow or wide beam)
- location of attention not necessarily same as eye fixation
- limited capacity
what controls the spotlight of attention
EXOGENOUS CONTROL: externally guided by a stimulus
INHIBITION OF RETURN (IOR)
Posner 1980
cue paradigm - cue captures attentional spotlight and this facilitates subsequent perceptual processing at that location (reduced RT)
Mitroff and Biggs (2013)
- airport search games
- groups of people who were very good at this - could have implications for who works this job
feature integration theory
- perceptual features are encoded in parallel and prior to attention
- if object has unique perceptual feature then it may be detected without need for attention
- if object shares features than cannot be detected from a single perceptual feature and attention is needed to search all candidates serially.
Attentional Networks
DORSAL (WHERE) PATHWAY - from the parietal lobes and is important for identification of objects within space
VENTRAL (WHAT) PATHWAY) - from the temporal lobes - leads to recognition and identification of objects.
dorso and ventro dorsal streams
dorso-dorsal network involved lateral intraparietal area (LIP) and frontal eye fields (FEF)
ventro-dorsal stream (right temporo-parietal junction and ventral frontal cortex) that interrupts any cognitive task in order to divert attention away from processing (i.e. you hear a scream)
hemispheric differences in parietal lobes
- hemispheric asymmetry
- right PL richer representation of space (left space and some right space)
- left PL less so
= pseudoneglect
types of neglect
unilateral, spatial or hemispatial
clinical tests of neglect -
- cancellation tasks (cross al the lines you can perceive) - patients with hemispheric neglect will cross lines only
- drawing: copying or from memory
perceptual versus representational neglect
- the brain contains different references for spatial and imagined events in external space
- neglect can affect memories of scenes (representational neglect
perceptual versus representational neglect
- the brain contains different references for spatial and imagined events in external space
- neglect can affect memories of scenes (representational neglect
plazza del duomo
- Ps with right PL lesions - asked to describe familiar place (the plazza)
- first asked to imagine themselves looking at the front of the cathedral from the opposite side of square AND then reverse the perspective
- what ever area was on the left visual field was neglected - however the spatial knowledge of the square is not lost but unavailable to report.
- hippocampus - considered to store ALLOCENTRIC map of space … and
- parietal lobes required for IMAGINING IT from a given viewpoint.
- example of a double dissociation
neglect for near versus far space
DOUBLE DISSOCIATION
- line bisection using pen and paper - impaired / laser
- backed up by single recordings from animals
- near space: supported by right parietal and frontal space
- far space : supported by visual cortex
personal versus peripersonal space:
body neglect = failure to groom left side of body, notice position of limbs or feel pain on left side
near space neglect: visual search of array of external objects
(Hussein et al 2001)
within objects versus between objects
- some neglect patients attend to object on left side of space but omit to attend to one half of object itself (object based neglect) - associated with damage to the SUPERIOR TEMPORAL GYRUS
- forms a double dissociation with space-based neglect
spatial versus object based neglect
patient with object neglect can detect differences on left side of an object even when falling onto right side of space
neglect as a disorder of attention
- not low level perception
- neglect patients still activate visual regions in OCCIPITAL LOBES
- They are often able to detect objects on the left if they are cued
affects auditory and tacticle judgements
visual extinction
- unawareness of a stimulus in the presence of a competing stimulus
- frog and sun.
neglect types (in terms of attention)
egocentric (with respect to observer) - e.g. line bisection
allocentric (with respect to another extrapersonal event) e.g. plazza del duomo
object-centred (with respect to a principal axis in the canonical representation of an object) e.g. with half of object, or half a picture
prism adaptation
patients wear prism lens glasses that shift view to the right
- visual feedback allows for correction
- effects persist after removal of lens
spatial memory
hippocampus
- Maguire et al 2006 and 2001 - cab drivers
hippocampus versus parietal lobes
parietal lobes: linking sensory and egocentric maps of space to create representations of visual environment
hippocampus stores long-term memory of space
(can work together)
video games - role in attention and learning
action video game playing = capable of altering range of visual skills
- perceptual learning tends to be specific with a trained task
- Ps who did action video games were much better at visual search tasks and contrast sensitivity and mental rotation
The test of variables of attention (TOVA)
- TOVA assesses impulsivity and sustained attention
- Ps required to press a key as fast as possible in response to target and to withhold responding to non-target stimuli
- in one condition - targets are rare and non-targets appear frequently (this measures SUSTAINED ATTENTION)
- in other condition - targets are frequent, non-targets are rare (this measures IMPULSIVITY)
TOVA and video games
video game players were faster in both conditions.
- but no difference in accuracy from controls.
