export_(PS) lecture 8 objectbased attention the cognitive neuropsychology of attention Flashcards
What was it claimed attention acts upon? What is the current notion of what it acts upon? (Object-based attention)
- It was thought it acts on a region of physical space
- It seems to act on a specific object (primary) in that space (secondary)
What did Rock & Gutman 1981 show about object based attention? (red vs green)
Participants attended to red line only even though green was in the same spotlight
In Tipper’s experiment what happens to the unattended shape?
It is not remembered consciously but it is perceived because it negatively primes subsequent tasks when it is not to be ignored (ie. slower to perceive when it is the target after it has been ignored before).
What was the evidence for Object-Based Attention in Duncan’s (1984) ‘boxes’ experiment?
better performance when having to judge 2 qualities of the same object, than qualities of different objects
cannot attend simultaneously to different objects, even if they occupy the same locations. It is an advantage just to select one.
Egly, Driver, Rafal (1994) - their experiment consistent of boxes on the left or right as location markers and they would cue the top or bottom of box (flash). What did this lead them to discover about object based attention and how?
- 1) possible miscue: cue upper right, target occurs at bottom of same box
- or 2) cue upper right (right box), present target at upper left (left box).
- RT time to 1) was faster than 2); meaning attention spreads to encompass the entirety of objects
Maybe perception may not spread across perceptual boundaries? What did Moore, Yantis, Baughans 1998) Occluding Bar experiment show about this?
Still found the same object advantage; rectangle was always seen as a continuous perceptual object. Curing part of object leads to whole object being selected for.
What was some Neuroimaging (fMRI) evidence for object based attention?
The Fusiform Face Area prefers faces while the parahippocampal place area prefers houses. When put in the same region the FFA or PPA are active depending on what people are attending to
What is Visual Neglect?
Insensitivity to stimuli on one side of visual space. Attentional in origin, not visual.
How does Visual Neglect occur?
From damage to the right parietal lobe
What does the right parietal lobe do? Refer to the dorsal stream.
Reflects lateralization of spatial function of brain. Visual information, initially encoded in occipital lobes, follows 1 of 2 streams (dorsal stream) to proceed into the parietal lobe. The dorsal stream is the “where” pathway; it is associated with processing spatial relations amongst objects and where stimuli are. Damage causes deficit in processing visual space on the left.
What did a right parietal lobe deficit patient do in the cancellation test?
Put a stroke through each line on the right side only
What was the implications of Cuing Deficits & Right Parietal Damage (Posner)?
- degree of seeing symptoms of neglect depend on attention allocation
- cue attention on left, performance normal.
- miscue on right, then present stimulus on the left; RT very slow (cost).
- Patients can still engage attention, but have difficulty disengaging & shifting in response to new information
Symptoms of Neglect: What is Extinction?
- Perceptual response to one stimulus (ie. comb) “extinguishes” response to the other (ie. apple).
- Damaged hemisphere is under-active; cannot activate enough resources to compete with other hemisphere
What is Balint’s syndrome?
caused by bilateral damage to parieto-occipital region, extremely rare; symptoms include optic ataxia , ocular apraxia (can’t shift fixation), and difficulty perceiving more than one object at a time (i.e. seeing the visual field as a whole)
Tipper (1991) set up a visual display and location markers, where a target could occur on the left or right. What is Object-Based Inhibition of Return that he discovered? (or rather how did it occur)
Inhibition of return tracks the cued marker to its new location!
Inhibition of Return follows the cued object; it is not confined to one region of space
Tipper & Behrmann, (1994) set up a visual display and location markers, where a target could occur on the left or right. A line joined the 2 location markers (barbell-like) What did they find was Object-Based Neglect?
- When marker was rotated 180 degrees, the longer RT was on the right side
- Neglect based deficit tracked from the left to the right side of space
- An object based phenomenon
EXAM Q10: Tipper & Colleagues carried out a cuing experiment in which a cue was presented & then the markers designating possible target locations were rotated to new positions in the display. They found that RT was slower at a new position if the marker had previously occupied a location that had been peripherally cued. Tipper et al interpreted this finding as showing: (ie. that attention operates primarily on the representations of…)
Objects rather than on the regions of space they occupy
In Negative Priming RT’s to a target stimulus are longer if…
it was a to-be-ignored stimulus on a preceding trial
The dorsal cortical pathway is thought to process information about:
The location of stimuli in space
Cuing studies with spatial neglect patients have found abnormally long RTs in responding to miscued stimuli in the
left visual field
In perceptual extinction, neglect patients show impairment in responding to…
2 strong stimuli
