Topic 5: Attention Flashcards
what is attention?
a limited capacity to process competing options in which attentional mechanisms select, modulate, and sustain focus on information most relevant for behaviour
what is the problem, importance, and challenge of attention?
P: allocate limited resources
I: prioritizing information
C: balance the need for selective focus to handle new situations
Source: Exogenous vs. Endogenous
Exo: environmental, reflexive, automatic, “bottom-up”
Endo: in the mind, voluntary, intentional, “top-down”
Target: External vs. Internal
Ext: sensory information in the environment
Int: mental representations in the mind
Type: Overt vs. Covert
Overt: movement of the sensory surface
Covert: no actual movement
Type: Transient vs. Sustained
Transient: momentary focus
Sustained: prolonged focus
Type: Selective vs. Divided
Selective: one thing to the exclusion of others
Divided: multiple things simultaneously
Dichotic Listening
when a person has headphones on, and different messages are sent to different ears. Person is told to pay attention to one ear or the other
Cherry’s Early all-or-none filtering (Broadbent’s filter model)
low level gating mechanism can filter out irrelevant information before the completion of sensory and perceptual analysis (couldn’t report the content)
Grey and Weddenburn’s Early Attenuation (Treisman’s attenuation theory)
meaning of unattended words are taken into account
McKay’s Late Selection Model
all stimuli are processes through the completion of sensory and perceptual processing before selection occurs (meaning of the same word differed depending on what was played to the unattended ear)
Strategic Control Model
top-down selection at early, middle, or late stages depending on the circumstances
EEG
measures surface electric fields generated by post-synaptic potentials in dendrites of neurons
Event-related potentials (ERPs)
the average of EEG signals at a specific time locked event (temporal precision plotted with negative up)
Brainstem evoked responses (BERs) or Auditory brainstem response (ABR)
- series of small electrical brain waves that are elicited during the first 10 ms after onset of brief auditory stimulus
- activity in the auditory brainstem nuclei and thalamus
- no attentional stream
Midlatency responses
- 10-50 ms after auditory sound
- early activity in the auditory cortex (A1) that effects attention
P20-50 Attention Effect
in midlatency responses, an enhancement of activity in attention that supports the early-selection theories
Late Waves
- continue for several hundreds of ms
- extending activity in A2 and A3
Attentional Stream Paradigm
two or more segregated series of stimulus are presented in parallel, and subjects attend to one to perform a task (dichotic listening tasks)
- EPR of both are compared
- effect in mid latency and late waves, but not in BEPs
Endogenous vs. Exogenous in Posner’s Spatial Curing Paradigm
endo: arrows; faster to respond to validly cued targets, slow to invalidly cued; accordance with early-selection models
exo: list flashes; respond faster to target presented in the cued location than the uncued
Inhibition of return
in exogenously cued spatial attention paradigm, there is a slower behavioural response to a target stimulus present at the validly cued location later than 300ms after the cue
what is the neural effect of a stimulus on a plot
positive signal at 100ms, then a negative one
what is the difference in the spikes on neural plot between an attended EEG and an unattended EEG
attended has was more activity with bigger spikes
Attention affect reentrant activity
following a stimulus of event, a process where activity is fed back to the same brain region that was activated earlier in the process (loops to get processes by higher areas again)
there are greater effects on which visual cortical areas from attention on stimulus processing
greater in low-level (V2, V3, V4) than in V1
monkey study in visual attention and V4
- visual cortical neurons fire strongest if a stimulus is in that cell’s receptive field, and has the right specific characteristics
- BUT there is a strong fire in attend vs. unattended even when the stimuli are the same
Orientation turning curve
attention causes scaling of response depending on the orientation
contrast sensitivity
if you present a stimulus that you can see, but not very well, attention increases how well you see it; spatial attention increase at lower an middle contrast levels where it would be more useful
differences in contrast levels in contrast sensitivity
- low contrast: small response, small change
- medium contrast: medium response, big change
- high contrast: big response, small change
visual attention in fusiform face area (FFA)
- FFA= neurons that respond to faces
- more activity when they are paying attention to faces than when they are passively viewing them, and even more than when they are paying attention to something else
Pop-out
rapidly detected target stimuli where a single feature is different from the distractors
Feature search
- pop out
- no sequential shifts of attention
- rapid
- in parallel
salient characteristics draw attention - same amount of time, regardless of how many distractors
- bottom up
- exogenous
- parietal then frontal
Conjunction Search
- more than one feature difference
- increase distractors = increase time
- reaction time is doubled when the object is not there because we have to search every single object whereas when the object is there, we can stop once we found it
- slope = how much more additional time (ideal person is 50ms added per additional item)
- frontal than parietal
Feature integration theory
a model of attention postulating that the visual perception system is organized as a set of feature maps, each proving information about the locations in the visual field of a particular feature
- attention is required to bind different feature into consciously experienced wholes in two stages
two stages of feature integration theory
- preattentive stage: analyzes what we see into literally features which does NOT require attention
- focused attention stage combines all of them, and DOES require attention
where does 1. attention based feature integration occur? 2. preventive feature extraction? 3. low-level sensory analysis?
- posterior parietal cortex
- extra-striate cortex
- striate cortex
why does conjunction search use the frontal lobe before the parietal lobe?
you have to bind features together, so the frontal/control parts of the brain have to be active first to search for the target in a systematic way
what happens when someone has damage to the right inferior parietal lobe?
deficits in spatial attention to the left side of personal and environmental space (contralateral)
T/F
those with unilateral (hemispatial) neglect have a deficit on their memory of one side of their personal and environmental space
false - deficit in attention, not memory. if someone points something out to them on the other side of their fields, they notice it, but they can’t notice anything on their own
what is the role of frontal eye fields (FEFs)?
- eye movements are closely tired to visual attention, therefore if you stimulate FEFs, you have greater firing in V4 (but only when the stimulus occurs in that V4 neurons receptive field)
T/F
stimulating FEF has the same effect on V4 as stimulating V4
true - stimulating FEF is kind of like manually turing on attention in the brain (only when there is a stimulus in the field)
IPS/FEF attentional control network
endogenous; voluntarily choosing to direct attention somewhere in a top-down control
TPJ/VFC attentional control network
exogenous; involuntary attention in a bottom up control
What is change blindness?
changes in a picture or scene over time are not immediately apparent if not attended to (e.g. flicker paradigm)
what is the source, target, and type of attention used in the flicker paradigm
Source = endogenous because you are voluntarily looking around trying to find what changing Target = external because you are looking at a picture Type = covert because your eyes are moving; transient because you are moving your eyes around the screen; selective because focus on each spot on the screen individually
