3 The Spatial Brain Flashcards
what is attention
Attention is the process by which certain information is selected for further processing and other information is discarded
Attention is the ability to select the stimulus, focus on it, sustain that focus, and shift that focus
what does the brain not regard space as
• Brain doesn’t regard space as a continuous single entity
what are the 3 forms space exists in the brain
(1) Locations on sensory surfaces (e.g. the retina; retinocentric space)
(2) Location of objects relative to the body (egocentric space)
(3) Location of objects relative to each other (allocentric space)
how do we locate things
In order to locate things in space we use cross-modal perception (integrating information from sight, sound, touch…)
is attention directed
Attention tends to be directed to locations in space (space is a common dimension of different sensory systems and our motor system) – spotlight metaphor
do we have limited attention
Limited capacity to process all received information, so selection based on relevance or importance to current goals
why do we need attention
Attention may be needed to bind together different aspects of conscious perception (e.g. shape and colour, sound and vision)
what is retinocentric space
locations on sensory surfaces - the retina
what is egocentric space
locations of objects relative to the body
what is allocentric space
locations of objects relative to eachother
what is the spotlight metaphor of attention
• Spotlight may move from one location to another (e.g. in visual search)
• It may zoom in or out (narrow or wide “beam”), e.g. if attending to words or
attending to central letter in a word
• Location of attention not necessarily same as eye fixation (“looking out corner of
one’s eyes”) – however, there is a natural tendency for attention and eye-fixations
to go together
• Limited capacity: not everything is illuminated
is the spotlight limited
yes limited capacity - not everything is illuminated
what controls the spotlight
exogenous control
inhibition of return
what is exogenous control
externally guided by a stimulus
what is inhibition of return
IOR
spotlight can be guided by an external stimulus
e.g. flash of light
presented pps with squares
Presented pps with squares - see a target a red square press a button
Every now and then there was a flash of light as a cue where a potential target might appear and posner just measured reaction times
how do you use endogenous control in a visual search
scanning the environment to find something youre looking for
spotlight can be guided internally
examples of visual search
radiographers
airport security personnel
experts in visual search
visual search task in labs colour
flat - efficient - parallel
Arrays with many items and one is different which is target
Defined by one feature which is colour
When we have only one feature that is defining an item we find it immediately we don’t have to look we can just scan and know what is target
Flat efficient parallel search - finding of an item that is defined by only one feature really doesn’t matter on how many distractor or what is the display size we’re looking for this one will immediately pop out
visual search task in labs colour and oreintation
steep - inefficient - serial
On the other hand if we have a target that is defined by colour and orientation it takes a bit longer to find target bc we have to scan several items in display before we find the target
Steep in efficient serial
Bc we have to scan different distractor
Depends on the number of distractors and display size the more there are a the slower we are
If target is absent it takes us even longer bc we keep searching for target until we find it
what is feature integration theory
- Perceptual features (e.g. colour, line orientations) are encoded in parallel and prior to attention
- If an object has a unique perceptual feature then it may be detected without the need for attention – “pop-out” (left array)
- If an object shares features with other objects (right array) then it cannot be detected from a single perceptual feature and attention is needed to search all candidates serially
- “Pop-out” is not affected by number of items to be searched
what is ‘pop out’
a single feature search
what is conjunction search
target is defined by the combination of different features
reaction time increases with number of distractors
what is the dorsal pathway
reaches up into the parietal lobes and is important in processing information about where items are located and how they might be acted on, guiding movements such as grasping
where - tells us where the objects are located in space
sometimes called the how route bc it tells us how objects can be manipulated
mostly associated with parietal lobes
what is the ventral pathway
reaches down into the temporal lobes - this pathway processes information that leads to the recognition and identification of objects
ventral - what - tells us identity of object
what do the parietal lobes do
Space, Attention and Parietal Lobes
Parietal lobes specialized for spatial processing and have been called the “where” route (Ungerleider & Mishkin)
Parietal lobes also bring together different types of spatial representation that are needed for action (e.g. integrating visual space with body space) so also called the “how” route
once the information is processed through the visual system what happens
Once the information is processed through the visual system it leaves the visual system in two routes so the information is either processed through the dorsal route or the ventral route
what are the two main attention related networks
There are two main attention related networks depending on whether we employ attention internally or externally:
- a dorso-dorsal network (blue) involving lateral intraparietal area LIP and Frontal eye fields (FEF).
- ventro-dorsal stream (right tempo-parietal junction and ventral frontal cortex) that interrupts any cognitive task in order to divert attention away from processing - external deployment of attention
internal deployment of attention
If we engage in a certain visual task which is internal deployment of attention - blue network will be engaged - dorso-dorsal network - bc it involves parietal areas in particular lateral parietal areas such as superior parietal fields and frontal eye fields
Frontal eye fields are involved in voluntary eye movements and they control our eye movements so when we’re looking for things actively dorsal route is employed
external deployment of attention
if you hear a cry for help while you’re doing something else then this ventro-dorsal networks is employed x made up for areas such as temporal parietal junction particularly on the right side and the ventral frontal context such as the medial frontal gyrus and inferior frontal gyrus so this is when our attention is deployed externally
in humans there may be hemespheric asymmetry of…
parietal lobes
what does right parietal lobe contain
Right parietal lobe contains richer representation of space (left space and some right space)
what does left parietal lobe contain
Left parietal lobe contains an impoverished representation of space (predominantly of right side only)
what is pseudoneglect caused by
The greater spatial specialization of right parietal lobe means that we all
have a tendency to attend to left side of space (pseudoneglect)
what are parietal lobes important for
Parietal lobes important for deployment of attention whether it be externally or internally
Left space is more richly represented in brain that right space
do we have a leftward spatial bias
yes