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Chapter 7

PSYB57H3 Chapter 7: PSYB57 Lec 07 Ch 7

Course Code
George Cree

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PSYB51 Lec 07 Ch 7: Attention and Space
Attention: any of the very large set of selective processes in the brain. To deal with the
impossibility of handling all inputs at once, the nervous system has evolved mechanisms
that are able to bias processing to a subset of things, places, ideas, or moments in time.
- Attn can be internal or external. Ext. attn. refers to stimuli in the world
o Internal attn., ability to attend to one line of thought as opposed to
another or to select one response over another
- Attn can be overt or covert.
o Overt: refers to directing a sense organ at a stimulus fixating eyes on a
single world. Shift of attn. w/ movements of eyes
o Covert: ex. pointing your eyes to a book while paying attn. to a person to
the left. Shift of attn. w/o eye movements
- Divided attn.
o Ex. listening to music while reading
- Sustained attn.
o Ex. Watching the pot to note the moment the water begins to boil
Focus on: selective attn.: ability to pick 1 or few out of many stimuli
- Note that att’l ehaiss opeate i all of the seses
- Selective attention is a cognitive brain mechanism that enables one to process
relevant inputs, thoughts, or actions while ignoring others that are less
important, irrelevant or distracting
- Arousal: a global state of the brain reflecting an overall level of responsiveness
o There is a connection between arousal and attention but they are not the
same thing
Why we need attention
- Bottle necks: it is impossible to process everything at once
o Sensory cognitive motor
Why can attention help us?
- How is it that we are not lost? How is it that evolution gave us a chance in the
first place? How does it help us?
o It increases our chances, even though we could still die. How do we
survive all the lions out there? It might be difficult sometimes to even be
able to see the lion.
o Attention is that mechanism that helps us put things in order.
Where does attention play a role?
- Attention to cvision, audition/touch/smell, across modalities, attn. to thoughts,
motor tasks
Today: What effects does attn. have? Next week: attentional control and models of
How can we study attn.? (paradigms, IVs and DVs..) ways to quantify attn
- Cues influence/bias attn.
o Pose’s attetioal ueig paadig
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o Natural biases
o Feature-based cueing
- Visual search
- Attn in time
The physiological correlates of attn.
Scene perception
How we measure attn.
- RT: a measure of the time from the obset of a stimulus to a response
- Perception: perceptual thresholds and biases
- Motor accuracy
- Eye movements: overt shifts of attention but not covert shifts of attn.
o Often, there is a correlation, not always, but often.
o These are all behavourial measures
- Brain activity
Selection in Space
Epeiet o hat it eas to atted to a stiulus  pose simple probe
detection experiment measures RT (or perceptual thresholds)
- We want to be able to control attention before we measure it
- Subject in the experiment fixates on a central point (*). After Variable delay, a
test probe (X) appears in one of the two boxes
- All the subject needs to do is hit a response key as fast as possible when the
probe appears vs. auditory cues. When you hear a beep, you are more likely to
respond faster by ~20-30 msecs. The auditory system is quite a bit faster than
the visual system.
- The measure time of interest is the average rxn time (RT)
Changed situation: the subject is given a cue
- The cue is the change in the outline colour of one of the two boxes (peripheral
cue). Pess the utto he ou see the ed dot, igoe the suae. It does’t
matter at all (it does influence results ut does’t eall hae to do ith the task
- With a valid cue (the target is on the same side as the target), the RT increases
- The invalid cue (target is on the opposite side of the target) = RT decreases
- Even if you know the target is on the wrong side, ou a’t help it. You attetio
just shifts there
- Result: attetio shifts efleiel e a’t help it.
Comparison to first no-cue control situation: subject responds faster to the probe
eause she is paig att. to the oet loatio
- Cue: a stimulus that might indicate where (or what) a subsequent stimulus will
be valid vs. invalid vs. neutral => cueing effect (the cue makes a difference even
though it does’t atter. This is the difference between the invalid & valid cues)
o The diffeee i RT ai atiit, hatee ou’e easuig et
between the effect of a valid vs. an invalid cue
o RTs for neutral cues are half way between valid and invalid
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Cueing is a tool for examining attention
- Behaviour can be stimulus driven or voluntary
o Monosynaptic reflex (knee jerk vs. kicking)
Another kind of cue: red for is a symbolic cue but can also direct attention.
- Now there are rules:
o If the cue is green, the probe is likely to be on the left
o If the cue is red, the probe is likely to be on the right
- This cue is invalid because the cued location is on the right but the probe
appears on the left
- RTs are slow here than the control condition because the subject has been
tricked into attending to the wrong location
Exogenous cue: seem common to summon attn. automatically by virtue of their physical
salience (peripheral)
Endogenous cue: consider them something like instructions that can be voluntarily
obeyed (symbolic)
Stimulus-driven cues: info conveyed through previous events at the same location
(involuntary, reflexive, peripheral, exogenous)
- All of these terms more of less mean the same thing (the ones in the brackets)
Voluntary cues: (spatial) info conveyed through cognitions and memory, often based on
language or other symbols (symbolic, central endogenous)
Whats the difference between stimulus-driven/peripheral and voluntary/symbolic?
- Partially independent neutral structures
Stimulus onset synchrony (SOA): The time between the onset of one stimulus and the
onset of another (this is a behavioural phenomenon)
- Different time courses of SOAs; slower effects for voluntary cues
- Ex. The time between the cue and the target
- Inhibition of return (IOR)
- If you extend SOA longer, at some point, you might just give up attention on that
location (cueing effect)
Inhibition of return: The relative difficulty in getting attention (or the eyes) to move back
to a recently attended (or fixated) location
- Helps to keep you from getting stuck continually revisiting one spot
- When the cueing effect is gone, it becomes negative. At the valid location, now
ou’e eoe sloe tha ou ialid etu
- If e did’t hae ihiitio of etu, e a’t disegage fo the ost saliet
stimulus. We are able to at some point, disengage from very salient stimuli
because it becomes uninteresting.
- Occurs only for stimulus driven attention
Selection in Space
In a cueing experiment, attention starts at the fixation point and somehow ends up at
the cued location
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