Attention Flashcards
What is attention?
Given limited capacity to process competing options, attentional mechanisms select, modulate, and sustain focus on information most relevant for behavior
Attention sources
- Exogenous: in the environment, reflexive, automatic, “bottom-up”
- Endogenous: in the mind, voluntary, intentional, “top-down”
Attention targets
- External: sensory info, in the environment
- A sensory modality, spatial location, feature, or object
- Internal: mental representations, in the mind
- A memory, imagery, or plan
Attention types
- Overt and covert
- Transient and sustained
- Selective and divided
Overt vs. Covert
- Overt: Involves actual movement of the sensory surface, e.g.: moving
the eyes, directing the ear - Covert: Does not involve actual movement, e.g.: “looking out the corner
of your eye”, “eavesdropping on a conversation at the next table”
transient vs. sustained
- Transient: Momentary focus on something
- Sustained: Prolonged focus on something
Selective vs. divided
- Selective: Focus on one thing to the exclusion of others
- Divided: Try to focus on multiple things simultaneously
Dichotic listening
-Source: endogenous
● “Attend to the left ear”
- Target: external
● Sounds entering ear
- Covert
- Sustained
- Selective
Dichotic listening: Cherry (1953)
- Could report existence of
message - Could report gender of
speaker - Could NOT report content
Dichotic listening: Moray (1959)
- Could report change in
gender of speaker - Could report change in
pitch of a tone - Could NOT report a word
repeated 35 times! - Could report hearing own
name
Dichotic listening: Gray & Weddeburn (1960)
- Told to shadow left ear
- Left ear hears: “Dear 7 Jane”
- Right ear hears: “9 Aunt 6”
- Participant reports: “Dear Aunt Jane”
- Meaning of unattended words
being taken into account
Dichotic listening: McKay (1973)
- Meaning of biasing word
(“river” or “money”) in
unattended ear affected
participants’ choice - However, participants were
unaware of presentation of
biasing words
Attentional selection models
- Early all-or-none filtering (Broadbent) occurs between low-level perceptual and high-level semantic analysis
- Early attenuation (Treisman) occurs between low-level perceptual and high-level semantic analysis
- Late selection model (McKay) occurs between high-level semantic analysis and decision-making/memory storage
- Strategic control of attention:
● Early versus late selection can
be chosen based on situation and approach
● Attention is applied by top-
down modulation
Electroencephalography (EEG)
- Non-invasive technique
- Measures surface electric fields generated by post- synaptic potentials in
dendrites of neurons - High temporal resolution: signal sampled >1000/sec
- Low spatial resolution: up to 256 electrodes
Event-related potentials (ERPs)
- Average of EEG signals
- Time-locked to event of interest
- Typically plotted with negative up
Attentional stream paradigm
- Random sequence of auditory “pips”
- Occasional deviant targets (different volume or pitch)
- Instructed to attend to one ear
- No effect of attention on brainstem evoked potentials
- Effect of attention on midlatency potentials (primary auditory) and late waves (secondary/tertiary auditory)
Posner’s orienting task
- Maintain central fixation
- Spatially cued trials
● 80% valid
● 20% invalid - Neutral trials
● No spatial cue - Source: endogenous
- Target: external
- Covert
- Transient
- Selective?
(McAdams and Maunsell, 1999)
- Orientation tuning curve: Attention causes gain (multiplicativescaling), but no change in feature selectivity
Visual attention and V4 neurons
Attention enhances signal-to-noise ratio:
- No contrast:
● Small response
● Small change
- Subthreshold/Medium:
● Medium response
● Big change
- High contrast
● Big response
● Small change
Synchronization in V1 and V4 (Bosman et al. 2005)
- Recording local field potentials (LFPs) in V1 & V4
- Attention to a stimulus increases synchronization between brain areas representing that stimulus
The effects of attention
- Attention affects reaction time, accuracy, and awareness of sensory stimuli
- Attention can have effects less than 100 ms after stimulus onset
- Attention modulates neural activity in brain areas for locations and objects
- Attention enhances neural response to attended stimuli (e.g. enhanced signal-to-noise ratio)
- Attention increases neural synchronization between brain areas
Unilateral (hemispatial) neglect
- A defict of attention
- A deficit in perceiving & responding to stimulation contralateral to damaged hemisphere
- Cannot be explained by primary sensory or motor disturbance
Reference frames of of neglect
- Spatial
● e.g. neglect of left side of space
● Location-based attention - Object-based
● e.g. neglect of left side of objects
● Object-based attention
Attentional control network
Regions involved in endogenous and exogenous shifts of attention
Role of frontal eye fields
FEF stimulation enhances V4 response, only when stimulus occurs in V4 receptive field
Change blindness
changes in a picture or scene over time are not immediately apparent if not attended to
Flicker paradigm (Resnick et al. 1997)
Image and one similar one with something missing or different flicker between each other
- endogenous, external, overt, transient, and selective
