Lecture 26- Visual Attention Flashcards
How does the difference in the subcortical and cortical structure functions make sense from an evolutionary perspective? (think frog)
-This distribution of labour makes sense when you consider it from an evolutionary perspective.
Think about how reflexive the behaviours of a frog are compared to humans. Then compare the
proportion of subcortical structures in frogs versus humans.
-The frog brain contains a high proportion of subcortical neurons.
-The human brain contains a relatively large proportion of cortical neurons compared to subcortical neurons. Consider the large number of gyri and sulci in the human cerebral cortex.
Do we consciously perceive everything that stimulates our sensory receptors?
- If you consider the massive quantity of stimuli detected by our sensory receptors at any given
time, you should agree that conscious awareness of each of those stimuli would completely
overload our system.
What is perception facilitated by?
- Perception can be facilitated by attention; however, attention to one part of the visual field can
come at the cost of neglecting other parts.
What is attention partially determined by?
What we attend to is determined in part by external factors (i.e., exogenous influences) and in
part by internal factors (i.e., endogenous influences).
What is the difference between covert and overt attention?
Overt shifts of attention involve movement of the eyes.
* However, attention can be redirected in the absence of an eye movement (i.e., covertly).
What was the ‘Event-related potential (ERP) experiment in neurologically-healthy adults: Effects of covert attention on activity in the occipital lobe’ experiment?
How does the brain respond when a stimulus appears at the location that attention is directed
compared to elsewhere?
* Task: Participants fixate on centre while stimuli
are flashed at either the left or right location.
During separate blocks, participants are asked
to covertly attend to either the left or right
location while maintaining fixation on centre.
* Results: A stronger neural signal occurred in
response to the stimulus when attention was
directed at the location of the stimulus
What is the ‘Event-related potential (ERP) experiment in neurologically-healthy adults: Effects of covert attention on activity in the occipital lobe’ experiment results consistent with?
This modulation of neural activity is consistent with the idea that selective attention to one part of the visual field comes at the cost of neglecting other parts.
What is the difference between Exogenous vs. Endogenous Movements of Attention? What parts of the brain are vital for each of these?
The ERP study that we just considered measured neural changes associated with attention that
was directed voluntarily.
* As with eye movements, attention can also be shifted reflexively in response to a sudden change
in the periphery.
* Exogenous shifts of attention are elicited by an external stimulus (i.e., reflexively). The superior
colliculus is important for reflexive movements of attention.
* Endogenous shifts of attention are elicited internally (i.e., voluntarily). Cortical neurons are
important for voluntary movements of attention.
Draw out what out an Exogenous Cue looks like and then what an endogenous cue looks like….
Answer in notes
How does attention facilitate responses?
When attention is directed toward a
location, and then a target appears
shortly afterward, the latency to
respond to that target is reduced
when the target appears at the
location of attention compared to
when the target appears at a
different location.
- Thus, attention facilitates responses.
What is inhibition of return?
When attention is directed toward a
location, and then there is a long
delay before a target appears, the
latency to respond to that target is
increased when the target appears at
the attended location compared to when the target appears at a different location.
* Inhibition of return is thought to facilitate efficient visual search by discouraging orienting
toward recently attended locations.
* Research indicates that stronger inhibition of return is associated with better driving
performance.
* Inhibition of return provides an example of a reflexive mechanism of attention.
.
What is the flanker task?
- The flanker task can be used to assess the efficacy of strategic control over attention (i.e., how easily distracted the participant is by the other letter, can they just fixate on the center and not be effected by the incongruent trials???).
- Instructions: Maintain fixation on the center of the screen. When a stimulus appears at center, indicate its identity by pressing the appropriate button as quickly as you can (but try not to make
mistakes).
-Note: there is two letters that appear 1 above the other. The center one is the only one you care about. Congruent trials are when both the letters are the same (either both K or both S) and incongruent trials is when the letters are different (one K and one S). Expect incongruent trails to take longer (longer RT) - Flanker effect = RTs on incongruent trials minus RTs on congruent trials.
The younger you are the lower the flanker effect, the least distracted you are/ the more strategic control you have over eye movements
How is driving performance effected by aging?
Aging is associated with worse driving performance.
- Age-related increases in distractibility may be one factor that underlies age-related deficits in
driving performance.
