L12 Flashcards
reflexive eye movements are generated by neurons in the superior colliculus and that voluntary eye movements depend on cortical neurons.
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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
All of the incoming information there’s no way you can process it all efficiently. This is where the attention system comes into play. It chooses important stimuli for you to focus on
You are still award of all the stimuli you are just not conchiolily awaer
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 an example of this
Eg if you are in a crowd and your friend is wearing a yellow top you will use yor attention system to look for yellow things
Attention has many advantages but it comes at the cost of neglecting other things in the EG visual field Eg too busy looking for yellow that you don’t see a steep and trip over
what is attention determined by
in part by external factors (i.e., exogenous influences)
and in part by internal factors (i.e., endogenous influences).
Endogenous = what you want to focus on (internal factors)
Exogenis just just an external factor (eg someone screaming)
what are overt shifts in attention
• Overt shifts of attention involve movement of the eyes.
what are covert shifts of attention
attention can be redirected in the absence of an eye movement
eg when you walk past someone sketchy and you dont want them to know that you are looking at them
what could you used to test for exogenus attention
green stars and one red star
your eyes will immeditly go to the red star because it is different
how to test for endogenous attention
green suns and red stars
find the red sun
you need to activly look for the red sun because there are other red objects in the image
Event-related potential (ERP) experiment in neurologically-healthy adults:
Effects of covert attention on activity in the occipital lobe
how can you study this
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
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
what did they find
A stronger neural signal occurred in response to the stimulus when attention was directed at the location of the stimulus.
• 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.
• The neural signal recorded from the right occipital lobe in response to a visual stimulus in the left hemifield was greater then when attention was directed to the right (controlater viasuion)
• 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
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what is Facilitation
When attention is directed toward a location (exogenous cue), and then a target appears shortly afterward (in that spot), the latency to respond to that target is reduced (faster reaction time) when the target appears at the location of attention compared to when the target appears at a
different location.
Thus, attention facilitates responses.
what happens when an exogenous cue is followed by a long delay
If you add a long delay then people are slower at get their attention to the position that had been drawn
Therefore long delay inhibbits response this is because after a period of time passes then the systen desides that onthing happens there therefore the system will inhibit that area so that you can pay attention to other stimuli
this is inhibittion return
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.
what does inhibition return facilitate
• Inhibition of return is thought to facilitate efficient visual search by discouraging orienting
toward recently attended locations.
