PSY605 - Attention

A cognitive system that allows preferential processing of relevant information while ignroing irrelevant or distracting information.

• Alerting - dysfunction: anxiety
• Orienting - dysfunction: depression
• Monitoring - dysfunction: ADHD

• active interplay between internal and external stimuli
• Internal: Somatic, affective, cognitive
• External: Perception

• Vigilance - The ability to maintain alertness continuously over time (sustained attention)
• Arousal - Tied to functioning of the autonomic nervous system - sympathetic)
• Overall level of wakefulness

Galvanic skin response

• Reticular activating system
• -Cell bodies in medulla & pons
• -Projects diffusely throughout the cortex

• Hyperfunctioning: Panic and anxiety
• Hypofunctioning: Unresponsive to dangerous stimuli

Select some information for further processing at the expense of selecting other information

Dichotic listening task (1940s)

• -Listen to 2 streams of info
• -Attend to one of the channels (i.e. left ear)
• -Much of the message form the unattended channel is "not heard"

• Select some information at the expense of selecting other information
• Bottleneck view of information processing (Broadbent)
• Attenuation theory (Treisman) - processing of unattended channel is diminshed (not absent) and increases when the info is relevant to the task

• Dichotic listening task
• Shadowing experiments

Sensory Input

• Perceptual Analysis
• BOTTLENECK
• Semantic Analysis

Response Selection & Execution

Sensory Input

Perceptual Analysis

• Semantic AnalysisResponse
• BOTTLENECK
• Selection & Execution

The ability to focus one's attention on a single speaker among a cacophony of conversation and background noise

• Dichotic listening with two stories that switch ears in the middle
• You stick to semantically consistent content
• Supports early selection (?)

• Items that easily pass through the unattend channel:
• - Own name
• - Words related to sex
• - Curse words

• Greater attenuation for neutral words relative to name
• Evidence for late selection

• Early:
• -Dichotic listening: Can't remember info from unattend channels
• -Perceptual factors influence attentional cuing effects
• -Attention influences the sensory-perceptual processing of information
• -Attention's effect is seen early in time in the visual processing stream, in early visual areas (ERP studies)

• Late:
• -Breakthrough phenomenon

• Covert attention
• - Controls for perceptual input and eye movement

Valid, invalid, and neutral trials

• Endogenous: Must actively decide to put attention there
• Exogenous: Stimulus draws attention itself

• Must do valid often enough for them to trust it (70% valid, 30% invalid)
• Attentional benefits: | Neutral - Valid |
• Attentional costs: | Neutral - Invalid |

• High Luminance - invalid RT is faster
• Valid - luminance doesn't change RT (it is "maxed out")
• So the cuing effect is greater during low relative to high luminance

• Impact of attention at cell's receptive field maximal at cell's selected orientation - Attention increases amplitude of cell's response
• Increase in baseline firing when attention is paid to receptive field
• So, baseline is shifted when attention is inside receptive field, as if that cell is getting ready

• Phasic
• -Evoked acitivity
• -Stimulus must be preferred by cell
• -Time lock to target
• -Greater when target is attended

• Tonic
• -Sustained activity
• -Location must be preferred by cell
• -Time lock to cue
• -Greater when attention is focused within cell's receptive field

Is inormation really irrelevant if we need to response to it?

Solution - Assessing the fate of unattended stimuli by measuring neural responses to them, which does not require judgment from the subject

• Press button when two symbols are the same and on attended side
• Electrode in right hemisphere, maximally sensitive to the left
• P1 component has a greater amplitude when attention on left

• Generated in V4
• It is a sensory-perceptual component
• Its amplitude will be greater for brighter stimuli (regardless of attention conditions)
• It if the first visually-evoked ERP component than is modulated by attention
• Its amplitude is greater when attention is directed to the contralateral (versus ipsilateral) hemifield
• Doesn't care about color (pink and green bars)

• Face-sensitive component
• Amplitude is greater as face saliency is greater
• Amplitude is greater when attention is directed to face versus nonface stimuli (but this effect is limited to conditions during which the face saliency is low)

All visual areas code for spatial location, in addition to another feature (orientation, color, motion, shape, face, etc.)

• Indivisible
• Moves spatially from one region to the next
• Enhances regions within the spotlight
• Size of the region may vary but capacity is limited
• Independent of eye-movement

• Disengage
• Move
• Engage

• Failure to respond to objects or events presented in the contralesional hemifield
• Lesions to the right parietal lobe (or frontal cortex, basal ganglia, or thalamus)

• Body-Center: anosagnosia, may include hemiplagia (inability to move one side of body)
• Scene-based: Environment centered
• Object-based: Object-centered

• Line bisection
• Target detection task
• Copying
• Spontaneous drawing
• Matching
• Implicit processing
• Memory tasks
• Posner cuing paradigm

• Dumbell, red side and green side -- is there an X in the red circle?
• Spatial based vs. Object based
• Object-based - still don't see X when rotated onto right side

Memory is intact but reporting requires attention

• Residual effects of neglect
• Stimulus on left - It's there
• Stimulus on right - It's there
• Stimulus on both sides - Only see right, neglect left

• Invalid - Faster ipsilateral to the lesion than contralateral
• Valid - Same speed regardless of side

With recovered patients, it's hard to disengage from right side cue to view left object (invalid)

• Severe attentional disorder; functionally blind
• Ocular apraxia - Stare at a fixated object and have great difficulty disengaging
• Simultagnosia - Can only perceive one object per fixation
• Spatial disorientation - Can't perceive spatial layout of objects around them
• Optic ataxia - inability to handle objects in space
• Often have to close their eyes to fixate on another object
• Bilateral parietal lesions

• -Difficulty in "move" component of spatial attention
• -Can't "keep steady" attention, and cuing doesn't help
• -Unilateral damage

• Posner Cuing
• -Ipsilateral - slightly faster with valid, and faster than contralateral
• -Contralateral - valid = invalid

• -Problem with "engage" component
• -Can't engage in one object, and cuing doesn't help
• -No problem selecting a single item when it is alone, but difficulty when multiple items present

• Posner Cuing
• -Ipsilateral - slightly faster with valid
• -Contralateral - valid = invalid, and as fast as valid in ipsilateral

• P1 doesn't care about color - amplitude is same
• P1 amplitude is greater for stimuli appearing on Left
• Selection negativity is sensitive to color
• Location-based selection precedes color-based selection

• ERP evidence: P1 for location occurs prior to SN for color
• Illusory conjunctions: In the absence of spatial attention, object features are miscombined

• 2THR3 --> 2THR3
• Without focused attention, features appear to be combined at random
• The miscombination of features form illusory objects in the absence of attention

Features are coded by separate systems

• Know this from:
• -Anatomical & Neurophysiological Evidence (modulatiry to visual system)
• -Neuropsychological evidence (brain damage)
• Brain imaging (fMRI and PET)

• Problem: How do we experience a coherent world?
• Solution: Feature Integration Theory

• Treisman
• Attention is used to bind features together
• Code one object at a time on the basis of its location
• Bind together whatever features are at that location

• Basic features - coded automatically, in parallel, without the need for spatial attention
• Conjunction of features - need spatial attention

• Parallel Search:
• One feature - processed together, search is automatic without need for spatial attention, regardless of number of distractors
• -Preattentive stage

• Serial search:
• Conjunction of features - Requires spatial attention to attend to each item until target is found, distractors increase reaction time
• -Attentional stage

Visual search experiments