Cognitive and biopsychology lecture 3 Flashcards
What is bottom up attention?
passive modes of attention, exogenous attention. Alertness or arousal, reflexive attention (towards a bolt of lightning)
what is top down attention?
active modes of attention, endogenous attention. selective attention choosing whether to listen and look at lecturer
What are the cells of the retina made up of?
photoreceptor cells and can be broken down into two areas:
fovea (more cells - most cones)
parafovea (less cells - most rods)
what is the fovea?
centre of retina
what is the diameter of the fovea?
1mm
what does the fovea have?
high concentration of cone photoreceptors (colour, high spatial acuity0
What percentage of optic nerve fibers come from the fovea?
50%
Where in the eye is the greatest visual accuracy achieved?
in the fovea - further away from retina lower the acuity
what needs to be processed in the fovea?
areas of detail
what is the parafovea?
higher density of rod photoreceptors
what are the characteristics of the parafovea?
- no colour
- low spatial acuity
- better with low light vision and motion
What is a fixation?
when an eye is table
what is the saccade?
when they eye is moving in a ballistic way
How many eye movements are made per second?
3 eye movements
What does a brain do with our eye movements?
brain fills in the gap and uses our frequent eye movements to update and hold visual info.
How is the perception of the world made?
by amalgamating visual snapshots and knowledge about our environment
What is saccadic suppression
don’t perceive our own saccades
Why does saccadic suppression happen?
to suppress motion blur during the saccades
How many visual degrees per second can the eye
travel up to?
900 visual degrees per second (perceive a stable world)
what is overt attention
focus of attention is what fovea is currently looking at
what is attended info?
info in or around the fovea
what is unattended info
everything else
Characteristics of overt attention
slow - around 3-4 saccades per second (1 every 300 ms)
Characteristics of covert attention?
faster - 50ms to shift
what is covert visual attention?
attentional spotlight: focused visual attention resembles a spotlightb
example of covert visual attention
enhance attention w/in a small region of the visual field but not outside the beam of attentional spotlight (Posner 1980)
What is attention directed to?
a given region of the visual field