Lecture 3 - The Attending Brain Flashcards
What is inattentional blindness?
Failure to be aware of a visual stimulus because attention has been directed away from it
What is pseudo-neglect?
Failure to attend to left side of space
What is the Posner spatial cueing task?
Spatial attention - fixation on computer screen, followed by a cue indicating location of target. After delay, target presented at cued location or different location. By comparing reaction times = examine effects of spatial attention on information processing. How attention can enhance the processing of info while suppressing distractions.
What is exogenous orienting?
Attention that is externally guided by a stimulus
What is endogenous orienting?
Attention is guided by the goals of the perceiver - VISUAL SEARCH, SCANNING!
What is inhibition of return
A slowing reaction time associated with going back to a previously attended location. In the Posner cueing task - flashlight / invalid cue causes PPT to be slower at attending to the target - distracting
What is Feature Integration Theory (FIT) - Treisman & Gelade, 1980
How attention selects perceptual features of objects - when a single letter differs in colour to the others it will stand out (feature detection) - pop out affect. When there are two or more features - attention is required to SEARCH
What are illusory conjunctions?
Visual features of two different objects are wrongly perceived as being associated with only one object
What is the ventral route?
Connects visual cortex to temporal lobes - WHAT PATHWAY associated with recognition of objects and faces. Processing without awareness
What is the dorsal route?
Connects visual cortex to parietal lobe - WHERE PATHWAY (spatial processing). important for conscious experiences
What is allocentric space?
Map of space coding the locations of objects relative to each other. Stored in Hippocampus
What is peri-personal space?
Space within reaching distance - the space that surrounds us
What is the frontal eye field?
Part of the frontal lobes responsible for voluntary eye movement
How does neglect arise?
Loss of neurons dedicated for representation to that space - failure to shift attention - often after a stroke to right hemisphere
Mort et al., 2003 - Is the visual field affected in neglect?
Neglect is not a disorder of low-level visual perception as objects in neglected visual field still activate visual regions. However neglect is most commonly observed in the visual modality.
Vuilleumier et al. (2002) study - proof that neglect patients can process without conscious awareness
- Shown pictures of objects in left, right or both fields.
- When presented simultaneously patients extinguished the one on the left and only reported the one on the right
- Claimed to have never seen the left picture
- When asked to identify a degraded picture of the object - performance was facilitated
- Processed unconsciously
Representational neglect
Affects memories of scenes - failure to attend to one side of an imagined space
What is perceptual neglect?
Neglect of stimuli in the external environment that a person perceives. In line bisection an individual with neglect will mark the line towards the right and ignore the left
What is representational neglect?
Neglect of imagined / mental representations of space. Neglect patients exhibit deficits in representation of imagining objects and scenes - bias towards one side of imagined space
What is a double dissociation in relation to perceptual / representational neglect?
Two functions are impaired or preserved independently of each other. Some people exhibit perceptual neglect without representational neglect. Spatial reference frames used for perceiving external space and representing imagined space are SEPARATE / DISTINCT
What is the Piazza del Duomo experiment?
- 2 patients with large right parietal lesions (neglect to left)
- Asked to describe a familiar place (Piazza del Duomo in Milan) from 2 different perspectives
- Showed double dissociation between perceptual and representational neglect
- Different spatial reference frames for external vs imagined
- Spatial knowledge not lost, unavailable to report
- Pseudo-neglect = shift attention to the left
- Parietal lobes required for IMAGINING it from a given viewpoint - DAMAGED IN NEGLECT PATIENTS
What is near space neglect?
Visual search of external objects
