Define Attention
The process by which certain information is selected for further processing and other information is discarded.
Why is attention important?
- Attention is needed in order to avoid sensory overload as there is a limited capacity to process all received information.
- Attention may be needed to bind together different aspects of conscious perception (e.g. shape and colour, sound and vision)
What is the Spotlight Metaphor of Attention?
- Attention tends to be directed to locations in space
(space is a common dimension of different sensory systems and our motor system). - Spotlight may move from one location to another (e.g. in visual search) or it may zoom in or out.
What controls the spotlight?
- Exogenous control – externally guided by a stimulus
- Endogenous control - guided by the goals of the perceiver.
- Inhibition of Return (IOR) – slowing of speed of processing when going back to previously attended location
What did Posner, (1980) study?
measured reaction time to identify target after cued light is presented.
What did Posner, (1980) find?
- When there was no cue at first they were slow but then improved at the task.
- if the cue was introduced and it was close in time (150ms) to the target then Ps were significantly faster at detecting target.
- if the cue was longer than 150ms away from target then Ps became slower at detecting target
Endogenous control
- guided by the goals of the perceiver.
- Related to properties of the task
Define Inattentional blindness
A failure to be aware of a visual stimulus because attention is directed away from it
Define Change Blindness
A failure to notice the appearance/disappearance of objects between two alternating images.
Define Orienting
The movement of attention from one location to another
What was the explanation for Posner’s (1980) results?
- if target is presented 150ms after cue because Ps had deployed attention.
- if target is presented 150+ms after cue Ps are already searching the space so it takes longer. There is a cost of returning to previously searched space (inhibition of return)
Define Visual Search
- A task of detecting the presence or absence of a specified target object in an array of other destructive objects.
- Scanning the environment to find something you are looking for.
What did the visual search study by Mitroff & Biggs (2013) find?
- When items are rare people are very bad at finding them because most of the time there is nothing to be found
- When appearance frequency of rare items increases then people become better at finding them.
What is the flat/efficient/parallel search?
The target immediately pops out from the distractor items because it has one distinct feature. (single feature search)
the reaction time doesn’t change regardless of the display size.
What is the Steep/inefficient/serial search?
It takes longer to find the target because the target is defined by multiple factors. (conjunction search)
The reaction time depends on the size of the display and the number of distractors.
What is the Feature Integration Theory (FIT)?
- 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 are the 2 attention related networks?
- a dorso-dorsal network (blue) involving lateral intraparietal area LIP and Frontal eye fields (FEF).
§ Attention employed internally
§ FEF control voluntary eye movements (looking for things actively) - ventro-dorsal stream (right tempo-parietal junction and ventral frontal cortex) that interrupts any cognitive task in order to divert attention away from processing
§ Attention employed externally
What are the differences in the 2 parietal lobes in human?
- hemispheric asymmetry of parietal lobes
- Right parietal lobe contains richer representation of space (left space and some right space)
○ Left side of the body is more richly presented in the brain - Left parietal lobe contains an impoverished representation of space (predominantly of right side only)
- The greater spatial specialisation of right parietal lobe means that we all have a tendency to attend to left side of space (pseudo-neglect).
How did Nichols, (1999) show a Leftwards Spatial Bias?
- Study tested for psuedo-neglect.
- Asked Ps which bar is darker
- Ps chose bottom bar because of attention is drawn by the darker side on the left side of the space.
Define Neglect.
Patients fail to attend to stimuli on the opposite side of space to their lesion (a right sided lesion would affect the left side of the space).
Neglect is a disorder which can reduce a person’s ability to look, listen or make movements towards one half of their environment.
What is the common lesion found in neglect?
- right angular gyrus - rAG
- rAG needs to be damaged for people to experience neglect - !disputed finding!
What are the clinical tests for neglect?
- line bisection - have to draw centre on multiple lines
- cancellation tasks - need to cancel out all lines/stars.
- Drawing - need to copy drawing
What is Perceptual neglect?
cannot perceive half of the space
What is Representational neglect?
Neglect can affect memories of scenes
