Week 4 - Attention Flashcards
(32 cards)
Chapter 22 - Attention
What is Attention
Definition
- A process of selective awareness and response to stimuli
- Often described as a mental spotlight - can be directed to external stimuli, memories, or motor programs and can occur consciously or unconsciously
- Top-down, selective mechanism
- Filters specific sensory information for processing
- Takes time
Chapter 22 - Attention
Automatic processing
Definition
- Unconscious, involuntary, and without focused attention
- Does not intefere with ongoing tasks
- Can be innate or highly practiced behaviours
- Operates via bottom-up processing: stimulus driven (reaction based on input rather than intention).
Chapter 22 - Attention
Conscious (controlled) processing
Definition
- Effortful, intentional, requires focused attention.
- Top-down processing: conceptually driven (relies on expectations and memory)
Chapter 22 - Attention
Feature vs conjunction search
Treisman
Feature search (automatic):
* Ex: spotting a T among L’s or Q among O’s
* Search time is independent of number of distractors
* Target “pops out”
* No focused attention needed.
* Bottom-up process
Conjunction search (conscious):
* Ex: searching to a T among L’s and I’s - shares features with distractors
* Search time is serial = attention moves across items one by one
* Search time increases linearly with number of distractors
* Requires focused attention
* Top-down process
Chapter 22 - Attention
Key points for Treisman’s research
Treisman
- Some visual processing is automatic, requiring no focus
- Conjunction search requires attention to combinations of features
- Practice does not eliminate the need for serial processing
- Feature processing is likely innate and biologically grounded in the visual system
Chapter 22 - Attention
Treisman’s featue integration theory
Treisman
Parallel feature maps = unified object perception:
* Visual system encodes colour, orientation, size, depth etc in seperate maps.
* Attention is the “glue” that binds features into object files.
* “Fixation of attention” binds features located at the same spatial location
* Neural basis = attention modulates neural activity in higher visual areas, not just V1.
Chapter 22 - Attention
Emotional feature detection
Eastwood
- Sad or negative stimuli are detected faster.
- Evolutionary perspective: fear/danger stimuli are prioritised and it may reflect the amygdala’s sensitivity to threatening cues.
Chapter 22 - Attention
What makes a process automatic vs conscious?
Attention, speed, awareness, processing type, visual search
Attention:
* Automatic = not required
* Conscious = required
Speed:
* Automatic = fast
* Conscious = slow
Awareness:
* Automatic = absent
* Conscious = present
Processing type:
* Automatic = bottom-up (data-driven)
* Conscious = top-down (goal-driven)
Visual search:
* Automatic = feature pop-out
* Conscious = conjunction (serial search)
Chapter 22 - Attention
Key principle
Neurophysiological evidence of attention
- To show a neuron responds due to attention, the same stimulus must elicit different responses depending on its location or relevance.
- This rules out that neural changes are due to stimulus features.
Chapter 22 - Attention
Takeaway from monkey experiements
Neurophysiological evidence of attention
- Neurons can be trained to respond selectively to attended locations
- 2 types of visual attention: ventral stream (object recognition for selecting stimuli) and dorsal stream (spatial processing for selecting and directing movements).
Chapter 22 - Attention
Divided attention
Neurophysiological evidence of attention
Concept of processing bottleneck:
* Limited attentional capacity - we cannot process everything at once.
* if multiple tasks overload the system - a bottleneck appears and performance suffers.
Chapter 22 - Attention
Selective attention
Neurophysiological evidence of attention
- Attentional effort changes how neurons responds, specifically for V4 (color and orientation)
- Cells in the pulvinar respond selectively to visual stimuli (more vigorously when stimuli are targets of behaviour)
Chapter 22 - Attention
The “Binding problem”
Parallel processing of sensory input
- When attention is focused on one object, the visual system binds its features into a coherent whole.
- When multiple objects are present, the visual system struggles to bind features = binding problems
- Items not in the spotlight of attention are processed as seperate items.
Chapter 22 - Attention
Electrophysiology in monkeys (area TE)
Parallel processing of sensory input
- Area TE neurons can process multiple items in cluttered scenes in parall.
- Possible due to neurons tuned to complex configurations and serial selection (rapid cycling through items in brief intervals enables parall processing via temporal division)
Chapter 22 - Attention
fMRI evidence
Parallel processing of sensory input
Unimodal attention:
* Visual attention = increased visual cortex activity
* Auditory attention = increased secondary auditory cortex
Divided attention (to both):
* Decreased total sensory activation (less than sum of both)
* Increased activation in left DLPFC
* Indicates executive control of attention allocation
Chapter 22 - Attention
Interpretation
Parallel processing of sensory input
- Selective attention recruits task-relevant sensory areas.
- Divided attention relies on frontal executive regions like DLPFC to manage multiple streams
Chapter 22 - Attention
Corbetta’s research
Different attentional tasks activate distinct brain areas:
* Location-based attention = posterior parietal cortex
* Feature-based attention = occipitotemporal areas
General attention system includes:
* ACC
* DLPFC
Suggests attentional control networks extend beyond sensory areas.
Chapter 22 - Attention
Model of discrete attentional networks by Mike Posner and Steve peterson
Networks of attention
Key concepts and main networks (3)
Key concepts:
1. Anatomical separation = attention systems are anatomicaly distinct from sensory systems.
2. Distributed network = attention is not a single process but comprises distributed networks.
3. Three main networks = alerting, orienting, and executive control.
Chapter 22 - Attention
Alerting networks
Networks of attention by Posner
Function, neuroanatomy, neurotransmitters, behavioural role, and ACC role?
Function = maintains alertness and arousal.
Neuroanatomy:
* Rooted in the reticular activating system (RAS) in the midbrain.
* Forebrain = especially prefrontal and posterior parietal cortex.
Neurotransmitters:
* Enhanced by noradrenaline
* Not influenced by acetylcholine
Behavioural role = enhances reaction speed to warning cues without predicting what comes next.
Suppresses other processing by activating the ACC
Chapter 22 - Attention
Orienting network
Networks of attention by Posner
Function, two systems, disengagement -> reengagement, neurotransmitters
Function = prioritises specific sensory input or spatial location
Two systems identified:
1. Dorsal attention system: top-down (goal-driven), includes frontal eye fields and IPS/SPL, right-laterlised and linked to neglect.
2. Ventral attention system: bottom-up (stimulus-driven), includes temporoparietal junction (TPJ) and ventral frontal cortex (VFC), helps in behaviourally meaningful visual stimulus detection.
Disengagement -> reengagement: switching attention activates TPJ/VFC
Neurotransmitters: modulated by acetylcholine from the brainstem.
Chapter 22 - Attention
Dual executive networks
Networks of attention by Posner
Frontoparietal network and cingulo-opercular network
Two top-down control systems:
1. Frontoparietal network: supports moment-to-moment task adjustments, includes DLPFC, aPFC and IPS/IPL, active during transient demands at the beginning of a task.
2. Cingulo-opercular network: supports sustained task maintenance, includes dACC, active throughout the task duration.
These networks are functionally distinct but not mutually exclusive.
Chapter 22 - Attention
Attentional networks and self-control
Networks of attention
- Humans can voluntarily control cognition/emotion.
- Lateral prefrontal and cingulate cortices are involved in voluntary self-control
- Self-regulation develops around age 3-4 years with maturing executive systems.
Chapter 22 - Attention
Impaired attentional networks
Networks of attention
- Chronic stress alters the prefrontal cortex, impacting executive control of attention.
- It can impair DLPFC, ACC, Premotor, and posterior parietal cortices.
- Stress related attention impairments are reversible and therapeutically relevant.
Chapter 22 - Attention
Attentional spotlight via synchrony hypothesis
Mechanisms of attention
Attention increases the temporal alignment (synchronisation) of neural firing across a population of neurons coding for the same sensory input, thus highlighting those signals and facilitating their influence on downstream neurons.
Mechanically speaking, temporal aligment is:
* Action potentials from different neurons are timed so that they arrive simultaneously at a postsynaptic neuron.
* When two spikes arrive close in time, the postsynaptic neuron is more likely to reach firing threshold due to the summation of EPSPs.
* This temporal precision increases the salience of the selected signal in the downstream network.
