Attention I Flashcards
What is the definition of attention?
Attention is the process by which the mind chooses from among the various stimuli that strike the senses at any given moment.
Describe the Cocktail Party Effect
- Focusing your attention on a specific conversation or stimuli, despite the various competing sounds and conversations around you
- The voice/stimuli you focus on might even be one that isn’t directed towards you
What is the difference between early selection model and late selection model?
- Early selection model argues that attention affects sensory selection early on
- Early = Sensory areas; Late = High level areas
Describe Dichotic Listening
Two streams of input entering your ears, with different content/pitch/etc
What is the evidence for early selection in a dichotic listening task?
- Event-related potentials in a dichotic listening task.
- When we measure the activity over the right auditory cortex, we measure the activity that comes in through the left ear (+ vice versa)
- Measure that activity when the subject attends to the input from left ear, compared to from right ear
- Shows difference in activation of sensory areas -> Early selection task
In summary, what are the evidences for early selection?
- Auditory cortical responses are affected by attention
- Auditory brainstem responses are not affected by attention
- But: Otoacoustic emissions are affected by attention? (research)
What are otoacoustic emissions?
- Faint sounds produced by the inner ear in response to external auditory stimuli
- Automatic and involuntary
Describe exogenous attention
transient, bottom-up, automatic
Describe endogenous attention
sustained, top-down, voluntary
Define interstimulus interval (ISI)
The time interval between Stimulus 1 and Stimulus 2
Define inhibition of return
Exogenous attention decreases reaction times for short ISIs, but increases them for long ISIs
Define covert attention
We attend to something we don’t look at
Define overt attention
Directly attending to a stimulus you’re looking at
Define spatial attention
Attention to a specific location in space, irrespective of what is present at that location
Define feature-based attention
Attention to specific stimulus features irrespective of where they are in our environment
Define object-based attention
Attention to parts of an object spreads automatically to the entire object
What is Broadbent’s model of attention?
- ## Early selection
Give examples in favour of early selection. Discuss the quality of evidence
- Auditory cortical responses are affected by attention
- Auditory brainstem responses are not affected by attention
- Contrary to the cat exp (which was not a good controlled exp), there is little evidence for auditory brainstem responses being affected by attention
- Poor evidence from psychophysical EEG exps - Otoacoustic emissions are affected by attention
- Imaging Evidence
- Spatial attention effects in multiple cortical areas as demonstrated by functional MRIs
How are features represented in the brain?
- Visual Cortex (V1/V2)
- Ventral Pathway -> Inferior temporal
- Dorsal Pathway -> Posterior parietal - Sub-modules
V1: Sub-modules that process colours, motion, form, etc.
V2: Same as V1 but broken down in a slightly more orderly manner
V4: Colours, form
MT: Motion - Where are they sent to
- From these sub-modules, the info about motion and depth (3D vision) is sent to the dorsal pathway
- While info about the colour and form goes to ventral pathway - Prediction
Feature selective attention should predominantly activate the maps (areas) that represent the feature of interest
How are objects represented in the brain?
- Emphasis on how attention automatically spreads across the whole object
How is space represented within visual areas across visual areas?
How can this be exploited to map attentional signals in different brain areas non-invasively?
What is the evidence for attentional modulation of single cell responses?
What does the biased competition theory of attention state?
Multiple stimuli or sensory inputs in the environment are processed in parallel by the brain, and attention biases the competition in favor of certain stimuli (enhancing their processing while suppressing others)
Key points:
- Parallel processing (process multiple stimuli simultaneously)
- Limited Processing Resources (thus, there is competition among stimuli for neural rep and processing)
- Attention as a Biasing Mechanism -> Selective Enhancement and Suppression
- Top-down and Bottom-up influences
- Neural Mechanisms
- Flexible and Dynamic Process
How is the biased competition theory reflected in single cell responses and in human fMRI?
- Research studied the effect of selective attention on the responses of a neuron in area V4 of macaque monkeys
- When the animal attended to effective sensory stimuli, the V4 neuron gave a good response
- When the animal attended to ineffective sensory stimuli, a poor response was generated
- The first burst (of neuronal firing rates) is to the cue, but the second burst in each image is to the target array, and reduction is observed when the animals attend the ineffective stimulus
Why would you expect feature selective attention signals in different areas of the brain?
(Hint: How are different features represented in the brain?)
What is the evidence of object-based attention (task, behaviour, imaging results?)
How can endogenous and exogenous attention be tested?
What is inhibition of return?
