CHAPTER 7 LECTURE NOTES
Review: What is a horopter?
we have two eyes. two visions of more or less same stuff.
when your fovea converge, the foveas are directly look at it. for fovea, there is no double vision but many other point where there is
also no double vision.areas where we donot have double vision when we converge our eyes etc.
3 points to get from the definition:
1)attention has to do with many things; inputs, thoughts and actions
2) is a facilitary and
3) supressory mechanism.
-vs arousal: there are processes that are inhibited while you are sleeping.
-attention and arousal are diff things.that doesn't mean they dont interact with each other.
-If low arousal, attention is low.
- as arousal increases, attention increases. if arousal increases more, attention is decreased.
attentional state can get compromised if too much arousal. i.e drinking two litres of coffee
why would too much arousal be detrimental to attention?
problems ignoring irrelvant things. arosual seems to activate all type of sensory input in global way. too much arousal = too much
sensory input. too much a challenge to ignore irrelevant things.(suppressory mechanism)
and can't focus on the things that u should.
why would u need attention?
1.-we have all sorts of bottlenecks. impossible to process everything at the same time.
-too much info, u can’t process all the details, hence hard to find Waldo.
-lack of brain to process everything so attention is good to have!
2. Bottleneck exist on sensory(lack of arms, demo of waldo) and cognitive level [we can only have 1 or 2 thoughts at same time.].also
motor (motor behaviour involving output to muscles, etc)
Why attention help us?
How does attention help us survive if u focus on one thing and ignore other important things?
-attention helps us to focus on things that have certain probabilities to be more important than others
Not always perfect i.e car accidents.
Hard to measure attention.only measurable if effects are seen.
Perceptual thresholds: less commonly use.
-how do your thresholds of perception change over time.
- the point at which I perceive a dim signal for the first time.
If paying attention, lower threshold!if paying attention to that source in one place, easier to detect even dimmer light.
Also studies have shown that if i pay attention to things, they may appear even more brighter and more longer.
-if u don’t pay attention to your motor actions, can be bad. i.e a player in a hockey game.
-professional athletes are very good at attentional tasks
-changes as a function of whether paying attention or not.
Eye movts: we look at where our eyes are look at and taking this as indicator to what we are paying attention to.
There’s not 1 to1 connection between eye movts and attention.i.e you can look at someone and pretend to be paying attention to
them but be paying attention to the time/clock.
But mostof the time you pay attention to what you are looking at.and make eye movts to what I am paying it
You can shift your attention from where your eyes are looking at.
Difficulting shifting eyes without shifting attention
Perceptual biases : how biases influence what we pay attention to. CUEING AS A TOOL FOR EXAMINING ATTENTION
Simple problem detection expmnt. Involves attention but you cannot manipulate it.
Cue : diff. doesnot require behaviour.not asked to press a button.posner would say to ignore the squares.
In these expmnts, your attention shifts either to valid or invalid side in an INVOLUNTARY fashion..u just can’t help but pay attention
to the square. The instruction was to ignore the square.not really reason o expect that where the square appears will be followed by
the stimulus. The squaer appears 50% on valid and 50% on invalid side.- stimulus-driven cue:SAME LOCATION AS THE TARGET
Voluntary arrow indicates where most likely target will occur. 80% of time in valid direction and 20% in invlaid direction.
Ppl know and learn that they can use the symbol and hence, shift their attention.makes sense to process the direction fo the error
and shift their attention.
-voluntary, intentionally shift attention.
People’s RT faster in valid condn than invalid and neutral.
Stimulus Onset asynchrony
-time between square and the stimulus (dot) to appear.
-time between arrow appears and the target
- takes time to cognitively process the arrow.is a simple must translate into a directional code.takes time. Must interpret it into some
-also depends on how complicated just learned to associate the new pesudocode with certain direction vs simple.
- SOA might have diff effects- might take you longer till u can shift attention.
Benefit kicks in with some delay because to process the symbol takes some time.
Attentional shift happens more quickly.
If u make the SOA really large,i.e sec, voluntary,
u can maintain attention for long.
but will decline at some point but u see the benefit
diff for stimulus-driven cue: benefit will decline and its gone , -ve benefit. U are starting to be slower at the square and then the
-is a disadvantage---IOR
and something in between stimulus-driven and voluntary.
-the face makes a gaze shift and is directed to either the valid or invalid side.
This will influence your attention.
-same face but flipped around!
-when it comes to gender perception, we pay attention to the right side of a face
-we pay attention to the left visual field, which is the right side of the person u are looking at.
-asymmetry!we pay attention to one side than other.
-has to do with brain lateralization and brain being asymmetrical.
Line-bisection task-also shows biases
-the line is actually in the middle
-there is a bias in doing these task, people see the line as either to the left or right
-mostly people perceive it to the left.—used to measure spatial neglect
Grating-scale task-mostly the same as the line-bisection task
-scrutinize the rectangle bar on the top and on the bottom
- Spat.freq increases or decreases. Which bar has more of the thinner /thicker bars?
- Biases in this task are really attentional bias
- Bias to the opposite side for thicker bars
- Differences between two baises reflect different forms of attention
- Bilateral negativity first, interhemisperic competition
- later asymmetrical negativity-right hemisphere wins
so far spaced-based cueing of attention but can bias attention from one sense to other
-from one modality to other.
-shifting attention to visual domain but not spatially but in feature domain Feature-based attention can be a disadvantage.
-pic is designed so that it’s a disadvantage to shift your attention to feature domain.
Zhang and Luck
-fixed on white point on screen and dots on the right side of diff colors.pay attention to the red dots and press when they get
Paying attention to one side and one color. Ignoring the other color that is getting ismmer.
Color represented voltage.
On the graph, voltage is x-axis.
2 diff conds: paying attention to the red dots, press button whenever they get dimmer
Control cond :pay attention when green dot s get dimmer
-after 100msec=P1, less of a response when pay attention to green. has to do with dimming of the stuff on the other side.
More of a response to dimming when you pay attention to somewhere in the visual field that is of the same feature i.e color as
opposed to the other colour.
~feature-based attention –occurs early
Always thought spatial attention works faster but this showed that its not the case
P1 reflects activity in visual areas outside of striate areas, which are extrastriate areas.
Striate cortex – is also known as visual cortex
- Nonspatial cueing
- High level features can be the shape or contour of an object.are more likely associated with higher visual areas
- On which side is the o