Kap. 4 - External attention

What is attention?

• What are attention’s bipolar subdivisions - explained in short?

Attention

• Family of cognitive mechanisms that combine to help us select, modulate, and sustain focus (vigilance) on information that relevant for behavior

• Helps us select and prioritize information because of our capacity-limited ability to process information

• Works as a gatekeeper:

  • Giving priority to some information at the expense of other

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Subdivisions

• External vs Internal

  • Whether your attention is focused on the physical environment or your own inner thoughts

• Explicit vs Implicit

  • Whether your attention is conscious or unconscious

• Covert vs Overt

  • Whether an observer can physically see where you are paying attention

• Endogenous vs Exogenous

  • Whether the control of your attention comes from your own internal goals or is forced by outside events

What is the distinction between internal and external attention?

• Are they completely unrelated to each other?

External attention

• How we attend outwardly/select and modulate sensory information

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Internal attention

• How we select, modulate, and maintain internally generated information

• Closely related to WM

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Relation to each other

• Useful to talk about them separately, but they are closely related

• Can influence each other!:

  • E.g.

    • Attention on daydreaming (internal) interferes with ability to attend to lecture (external)

What is the difference between explicit and implicit attention?

• Give an example of implicit attention that can be measured

Explicit attention

• Conscious awareness that can be self reported

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Implicit attention

• Unconscious awareness that is measured by response times or eye movements

• Shows that people can attend to things without being consciously aware of it

• E.g. - Blindsight

  • People with lesion in visual cortex, but have functioning eyes, can respond to and localize visual stimuli even though they self report that they didn’t see it

Can you always tell where people are paying attention? Why/why not?

Overt attention

• “Outwardly observable sign of where people are paying attention”

• Measuring overt attention:

  • Eye tracking

    • Cameras recording saccades (eye movements)

      • The eyes move around so that we can use the foveas - region of highest acuity - to bring objects of interest into sharp focus and capture fine visual details

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Covert attention

• Attention directed in a way that can’t be discerned by observable signs

  • Processing an object or location in visual scene (i.e. mentally shifting focus) without shifting gaze

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Does overt attention always correlate with covert attention?

• Attention is a function of the mind, not just the eyes

• Overt attention often match with covert, but not always!

  • E.g.

    • Experiment: Inattentional blindness with radiologists not covertly attending to the monkey, even though overtly seeing it

How have researchers distinguished between voluntary and reflexive attention?

Endogenous (voluntary) attention

• The effort to select goal-relevant information

  • Top-down control processes

• Endogenous (central) cues in Posner cueing task

  • Engages voluntary attention and can appear between the potential target locations and can indicate symbolically where the target is likely to appear

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Exogenous (reflexive) attention

• Attending to a particular stimulus because it has seized your attention

  • Bottom-up processes

• Time course

  • Reflexive attentional shifts:

    • Transient:

      • Benefits of reflexively processing stimuli at specific location peak after ca 150 ms

      • After 150 ms —> inhibition of return

        • Short period when processing at the location is suppressed

        • Aiding ability to find things!

• Exogenous (peripheral) cues in Posner cueing task

  • Engages reflexive attention and can appear at one of the target locations instead of between them

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Evidence to distinguish the two attentional mechanisms:

• Neural regions involved

  • Endogenous/Voluntary:

    • Certain areas along the dorsal portion of brain

  • Exogenous/Reflexive:

    • A network alongside the ventral side of brain

What is selective attention?

• Describe different ways that attention can select information from the world

Selective attention

• Singling out certain pieces of information to pay attention to among many

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Spatial attention

• “The ability to attend to regions in space“

  • Like a spotlight - illuminating and raising the profile of whatever falls within its focus

    • Enhances information in specific location and suppress information outside that location

      

      • 
        

  • Like a zoom lens - attentional resolution decreases as attentional breadth increases

    • Consistent with fMRI:

      • Attention to larger area visually —> spread of corresponding neural activation (in visual system) increased, but neural activity level within spread decreased

• E.g.

  • Posner cueing task

    • Faster and more accurate at responding to a target (in space) when a cue (in this case and arrow) predicts the target’s location

      • Slower if cue is invalid and doesn’t predict target

      • The difference of speed in reaction to valid vs invalid cues is used as index of movement spatial attention

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Feature-based attention

• “The ability to attend to or filter out information based on features like color, shape or motion“

• Neuroimaging:

  • Neural distinction between feature-based attention and spatial attention

    • Feature-based attention increase activity in neural regions that are sensitive to the target feature across the visual field

      • - even in absence of sensory stimulation

      • Neurons that are not responsive to the feature tuned to be prioritized exhibit suppressed sensitivity

  • Feature-based turning of attention often occur when preparing to search for a target - even though it hasn’t appeared yet

^.

Temporal attention

• “The ability to pay attention to points in time”

• E.g.

  • Attentional blink in RSVP task (Rapid serial visual presentation)

    • The second (T2) of two targets shown in rapid succession of items → more difficult to detect than the first (T1)

      • (if T2 appears within ca ½ a second of T1)

    • Explanation:

      • Attention needs a “resetting period“ before a second item can be brought to conscious awareness

^.

Object based attention

• “Selective attention to an object rather than to a point in space“

  • Objects as units of attention - i.e. attention to a part of the object entails attention to the whole object

  • Evidence:

    • E.g. - reaction to cue and target within the same object vs in different objects (s. 88)

      

      • Result:

        • The invalid cues slowed response time more when they appeared on the opposite rectangle (object) than on the same rectangle as the target

      • Meaning of result:

        • Visual attention is influenced by how we parse the world - (with objects as a unit of attention)

    • Spatial neglect by lesion in right hemisphere

      • Fail to process stimuli within left visual field

      • Evidence for object based attention:

        

        • Some of the patients fail to process left side of objects - even if it is situated in their right visual field

          • i.e. even if an object is moved entirely into a patient's "good" side of space, their brain still treats that object as a distinct entity with its own left and right side. Consequently, they will completely neglect the left side of that individual item.

What is the biased competition model of attention?

One of the most influential and empirically supported models of attention!

Claims:

• “Stimuli in a cluttered visual environment compete with each other to drive the responses of neurons in the visual system”

  • i.e.

    • The competition among stimuli is particularly fierce when they fall within the same perceptive field

      • (A given neuron’s preferred region of the visual field is known as that neuron’s receptive field)

      • The smaller the distance among the stimuli - the greater overlap in the neuron populations that are activated —> increased competition among neural representations

• “Selective attention biases the competition in favor of one stimulus over the others“

  • Selective attention is biases by:

    • Bottom-up selection

      • Salience of the physical features

      • When multiple stimuli are present at once (e.g., a "face-house" mixture), their neural representations automatically compete for processing resources

    • Top-down selection

      • Goal-relevance

      • Higher cortical areas (frontal and parietal attention networks) send feedback signals to bias the neural competition, selecting and prioritizing one representation over the other

  • Bias may be amplified by emotional arousal

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The model is supported by evidence of neural activity

• When competing stimuli simultaneously occupy a neuron’s receptive field, the visual cortical neuron highly sensitive to another stimulus - become less responsive

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Ambiguity resolution theory (of visual selective attention)

• Any one cluster of neurons can actively support several representations

  • So, presence of multiple stimuli —> ambiguity about which mental representation accurately reflect the external world

• Resolution: Attention

How do early selection and late selection accounts of attention differ?

• How do load theory and Treisman’s attenuator model fit in with/modify this distinction?

• What evidence supports these different accounts?

The relevant question: “at what point in the flow of information processing does attention do its selecting?“

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Early selection of attention

• The attention theory that we attentionally select stimuli on the basis of physical features - such as color, pitch, or location - and that we register their meaning only after selection

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Late selection of attention

• The attention theory that we process the meaning of everything around us before we select what will gain entry to heightened awareness

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Treisman’s attentuator model

• Claims: “Meaningful information needs to meet a lower threshold of processing in order to reach awareness“

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Modern Consensus: The locus of attentional selection is flexible (not fixed)!

What is the Load Theory of Attention, and how do its early perceptual and late cognitive mechanisms determine whether we get distracted?

Availability of mental resources to process information depends partly on the demands of an attended task

• The Limited Capacity Principle:

  • The brain has a limited pool of processing resources. Distraction depends entirely on how a task loads either your senses (Perceptual Load) or your brainpower (Cognitive Load).

    • High vs Low load:

      • If attended task has high load (demanding):

        • Few spare attentional resources for unattended information - filtering it out at early processing stage

          • Unattended information will not reach awareness nor interfere with attended task

      • If attended task has low load:

        • More spare attentional resources for unattended information - may let attention “spill over” to this

          • Unattended message more likely to reach awareness + interfere with task

    
    

  • .

    • Early Perceptual Filter - (Sensory Capacity):

      • High Perceptual Load:

        • Hard visual tasks (e.g., finding an 'X' hidden among mixed letters) consume all sensory capacity. Distractors (like a cartoon dog) are filtered out early and ignored.

      • Low Perceptual Load:

        • Easy visual tasks leave spare capacity that automatically "spills over" to irrelevant stimuli, making you highly susceptible to distraction

    

    
    

  • .

    • Late Cognitive Filter - (WM & Inhibition):

      • The Mechanism:

        • Managed by the prefrontal cortex, this active system keeps targets distinct from distractors

      

      • The Threat (Taxing Working Memory):

        • Keeping a high working memory load means inhibiting distractors is harder

          • Because working memory plays a critical role in inhibition

      • The Result:

        • When working memory load is high, the active inhibition fails, causing the processing of non-target/irrelevant information to increase

    

    • Summary of the opposite effects:

      • High Perceptual Load decreases distraction

        • (no raw sensory capacity left to see the distractor)

      • High Cognitive/Working Memory Load increases distraction

        • (the brain is too exhausted to actively inhibit and block the distractor)

What is the Binding Problem in perception, and what is required to solve it?

The Problem:

• Different features of a single object (e.g., a rolling red ball's shape, color, motion, and depth) are processed by separate, distinct areas of the cerebral cortex.

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Definition of Binding:

• The physiological process by which these isolated, scattered neural signals are combined to create a unified perception of a coherent object

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The Key Requirement:

• Focused attention is absolutely necessary to act as the glue for binding features together.

Is attentional selection purely early or late, and where does it occur in the brain?

Attentional selection is a flexible combination of both early and late selection!

• Attention does not happen at a single fixed bottleneck - It actually operates at many points throughout the information processing stream

• Evidence Basis:

  • Behavioral and physiological data show that the brain shifts its selection strategy dynamically based on the sensory and cognitive load of the task.

What is Broadbent’s Filter Model of Attention, what is its core flaw, and how did Treisman’s Attenuator Model resolve it?

Broadbent’s Model:

• Describes the flow of auditiv information processing pre- and post-attention.

  • It suggests information is attended or ignored based strictly on early physical characteristics (e.g., pitch, voice gender) prior to any semantic processing of meaning.

• Evidence Against It:

  • The filter is not absolute. People automatically notice words with high personal relevance—like their own name—even when presented entirely to an unattended ear (The Cocktail Party Effect).

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Treisman’s Resolution (Attenuator Model):

• Instead of a rigid "on/off" switch that blocks out meaning, the attentional filter acts as an attenuator (a volume knob).

  • It turns down the processing strength of unattended information, but highly meaningful words (like your name) still have a low enough activation threshold to break through into conscious awareness.

    • (Treisman's FIT then took these ideas about early vs. late processing and applied them directly to the visual world.)

What does Treisman’s Feature Integration Theory (FIT) suggest about our raw experience of the world during pre-attentive processing?

FIT:

• Explains how the brain pieces together a unified visual world. It proposes that visual perception happens in a strict two-stage process:

  • (1) Pre-attentive stage

  • (2) Focused attention stage

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The Pre-attentive Jumble:

• FIT suggests that prior to attention, we experience the world as a jumble of simple features (like individual shapes, colors, or orientations) that are completely unbound

• The neurological state of the information

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The Act of Binding:

• Focusing attention directly on an object acts as the glue that binds these features together, allowing us to perceive a meaningful, cohesive object.

Define pre-attentive processing and contrast how stimuli are analyzed in parallel versus serial processing

Preattentive processing

• The extent we process information before attentionally selecting it

• Parallell processing of stimuli

  • Analyzing of stimuli during preattentive processing

    • Taking in stimuli quickly all at once - taking in the whole scene simultaneously

  • Evidence:

    • When the target is characterized by a distinct feature (poping out):

      • Detection is quick, regardless of the search array’s size

    • When the target is characterized by a conjunction of features:

      • Search time increases as the search array gets larger

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Serial processing of stimuli

• Further analyzing of stimuli as they get attentionally selected

  • More slowly and one bit at a time

How do Visual Search Dynamics and Illusory Conjunctions provide empirical proof for Treisman's two-stage Feature Integration Theory?

Visual Search Dynamics

• (Proves Parallel vs. Serial Stages):

• Feature Search:

  • Finding a target with a single distinct trait (e.g., a white square among black circles) is instant and "pops out."

    • This proves the existence of a fast, automatic pre-attentive stage using parallel processing

• Conjunction Search:

  • Finding a target defined by a combination of traits (e.g., a white square among white circles and black squares) is significantly slower.

    • This proves the brain must switch to a focused attention stage using slow serial processing to scan items one bit at a time.

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Illusory Conjunctions

• (Proves Features Exist Unbound Prior to Attention):

• Task:

  • When flashed arrays of four letters - asked to report identities of two digits + the colors and positions of the letters

• Result:

  • Errors tend to reflect the incorrect combining of features (illusory conjuctions) presented

• Ergo:

  • We process features prior to selection, but need attention to combine them accurately

What is Balint's Syndrome, and how does patient R.M. provide neuropsychological proof for Feature Integration Theory (FIT)?

Definition

• A neurological condition resulting from bilateral parietal lobe damage that causes an inability to focus attention on individual objects.

The Case (Patient R.M.):

• When presented with two simple, different colored letters (a red 'T' and a blue 'O'), R.M. reported an illusory conjunction (e.g., calling it a "blue T") on 23 percent of the trials.

• The Paradox:

  • This binding error happened even when he was looking directly at one of the letters and had as long as 10 seconds to respond.

• Accompanying Deficits:

  • His lesions also caused severe deficits in locating and reaching for objects, and an inability to see more than one object at a time (dorsal simultanagnosia).

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The FIT Proof:

• Because parietal damage takes away the brain's ability to focus attention, features remain floating in the pre-attentive stage and cannot be correctly bound.

  • Proves that feature extraction and feature binding are handled by entirely separate neurological stages, and that attention is mandatory for accurate binding.

What is the setup of a dichotic listening task, and how does it support a pre-attentive filter?

Task:

• Listening to two different messages played simultaneously - actively only paying one of them attention (repeating this message out loud)

Result:

• Barely able to report anything about the unattended message:

  • Only the physical properties of the unattended stimuli are registered

    • Like: gender switch / pitch, and replaced voice by a 400Hz tone

    • This heavily supports a pre-attentive, early physical filter.

  • This heavily supports a pre-attentive, early physical filter

How are modulation and vigilance functions of attention different from the selection function of attention?

Selection of attention

• Acts like spotlight and filter out information - focusing on specific information

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Modulation of attention

• Attention’s ability to change the way we perceive a stimulus

  • i.e. Changes strength of neural processing for the selected stimuli

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Vigilance of attention

• Attention’s ability to highten attentional anticitpation, enabling us to better respond to stimuli before they appear

  • i.e. Maintains readiness over time

What evidence suggests that attention modulates our perceptions?

Study with Gabor patches

• Test:

  • Presented with two Gabor patches, asket to determine which of them had the highest dark/light contrast + the tilt

    

    • 
      

  • Patches were preceded by attention-grabbing cue in between flashes or at one of the patch locations

    • Goal: manipulating where allocating attention

• Result:

  • When cue flashed in between:

    • bias in reporting the tilt of one over the other

  • When cue flashed at one of the locations:

    • Perceive the patch as having higher contrast

• So,:

  • Spatial attention modulates how people perceive visual qualities (i.e. contrast) of a stimulus

How are measures of attentional vigilance relevant to the real world?

When given information about when a stimulus will appear, people are faster to respond to the target than when they are given no warning

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E.g.

• Continous performance task

  • Stay “on task” (i.e. vigilant) for a prolonged time period

  • Understanding factors that enable people to stay vigilant during such tasks has real-world importance

    • Factors e.g.: brain damage or little sleep

    • E.g. Baggage screeners at airports - looking for specific objects

      • Bad at detecting targets that appear rarely

Describe at least one way that inattentional blindness and change blindness differ from each other

Inattentional blindness

• When people fail to notice an unexpected item right in front of their eyes - when their attention is preoccupied

• Influenced by expectations

  • (i.e. maybe expecting to see the gorilla during the basketball playing, but not the color change of the curtains)

  • i.e. radiologists looking for nodules in lungs, but not covertly seeing the gorilla

• Influenced by feature-based attention - a selective attention process

  • i.e. “driving through” imaginary world on video, looking for a road sign with specific color - less likely to collide with motorcycle if it had the same color as the road sign

• Difference in overt and covert attention!

  • What is in covert attention depend on which aspect of visual information we select for further processing

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Change blindness

• Failure to notice large changes from one view to the next, and it reflects another, related failure of awareness in the absence of attention

• Difference from inattentional blindness:

  • Change blindness:

    • Can occur because people fail to compare two views of a stimulus in memory

  • Inattentional blindness

    • Occur because people fail to notice a stimulus at all

• E.g. - door experiment: asking for directions and changing the person

  • Result:

    • Many didn’t notice

  • Other suggestions based on results:

    • Likelihood of noticing the change depends on what aspect of the person’s appearance attended to:

      • If out-group member —> only encoding features enough to classify as out-group

      • In-group —> encoded more individuating features

What is one piece of evidence suggesting that attention and awareness may not be the same thing?

Attentional blink

• Test - finding two targets in a rapid serial visual presentation task

  • Pushes attention to its temporal limits

    • Increasing difficulty of attending to some stimuli because they appear too soon after another

  • Result:

    • Typically difficulty reporting the second target, it appearing too soon after the first target

  • So,

    • If attention is fully occupied, you can look directly at a stimulus without being consciously aware of it

      • i.e. focused attention is a required gateway for a stimulus to cross the threshold into conscious perception - without attention, no conscious perception

If we can be aware of only a few things at a time, why do we often feel like we experience a richly detailed world in any given moment?

• We can rapidly process the “gist” - the overall idea - of a scene more quickly than we can process a scene’s details

  • The gist information helps give a sense of a richly perceived world

  • Perception of the world is a construction of the mind:

    • Stitches together immediate sensory information with information from immediately preceding views

What are some factors that can guide our attention without our control or intention?

Attentional capture

• Stimuli that can draw our attention reflexively

• E.g.

  • Arrows - pointing in a direction

  • Eyes - looking in a direction

  • Exogenous cue flashing at location of upcoming target

  • High salience aspects (very different from surroundings)

• Saliency map - some cues have more power than others

  • In early processing, visual system computes the relative differences between visual signals across the visual field - forming topographical representation

  • E.g.

    • Response time slows if high salient distractor is shown (e.g. an irrelevant different color)

  • Overriding attentional capture of irrelevant information

    • If tuned attention for a particular feature

      • (i.e. if they know that a specific type of salient (e.g. sudden onset or different color) distractor will appear)

Describe different ways that emotion and learning appear to influence attention

Experience and learning directs attention

• Contextual cueing

  • Learning where to attend and what to expect based on statistical regularities in past experience

    • An effect that is observed when people search for a target in an array of non-targets over and over again, across many trials - faster at finding a target in repeated configurations

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Emotion-driven guidance of attention

• Emotion-driven attentional bias

  • When we show a preference to attend to emotional stimuli

    • E.g. in visual search experiments:

      • Detection of a visual target among distractors is faster if the target is emotional (rather than neutral)

      • Detection of a visual target among distractors is slower if the distractor is emotional (rather than neutral)

  
  

• E.g. emotional influence on selection

  • Emotional disorders:

    • Heightened tendencies to attend to emotionally negative information

    • E.g.

      • Phobia indviduals being faster at locating their specific fear

      • 
        

        

    • E.g.

      • General attentional deficit theory of pathological anxiety (Bishops, 2009)

        • A general attentional style (not specific to threats) where anxious individuals fail to ignore distractors when task demands are low, but match non-anxious levels of distractibility when their attention is fully occupied.

    • E.g.

      • Dot probe task

        • Test:

          • Try to respond quickly to a target that can appear in one of two locations

          • Prior to target, locations are occupied - one with threatening stimulus, the other neutral

          • 
            

            

        • Result:

          • Anxious:

            • Respond more quickly if target appears where the threat was

              • Since: attention is directed towards the location of perceived threat

          • Depressed:

            • Linger more on the threat

            • Have a harder time reacting if the target is shown “behind” the non-threatening target

  .

  • Emotion and temporal attention

    • Attentional blink

      • If first target is emotional, it causes more impairments for detection of the next stimuli

      

      • Connected to amygdala - if lesion, then this effect doesn’t occur

    • Emotion-induced blindness

      • The failure to see rapidly presented targets that appear right after a rapidly presented emotional non-target

• .

  • Value-modulated attentional capture

    • The reflexive allocation of attention based on learned value

    • E.g.

      • Doing a task where you know you’ll gain money - higher stakes —> worse performance

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• E.g. - emotional influence on modulation

  • Emotional face shown before Gabor patch —> contrast sensitivity increased for the task

    • Effect was independent of spatial location - when faces appeared in different location as Gabor patch

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• E.g. - Broaden-and-build theory on emotional states affecting attention

  • Positive emotions —> widen the range of information people readily consider and attend to (global bias)

    • But if positive emotion is an “approach motivation” —> less likely to have global bias

  • Negative emotions —> narrow the range of information people consider

What is the primary brain structure responsible for boosting sensory responses to emotional stimuli, and what happens when it is lesioned?

The amygdala

• Core function:

  • Acts as the crucial source for affective biases on perception and attention to maintain vigilance

• Connectivity:

  • Receives rich sensory inputs from all modalities and sends widespread projections to cortical and subcortical regions

  • Cortical modulation:

    • Enhances visual and sensory processing by boosting activation in cortical areas that are already specialized for that stimulus type (e.g., emotional faces, bodies, or voices)

• When lesioned:

  • The enhanced processing for emotionally salient events is selectively impaired, while basic perceptual processing (e.g., distinguishing faces from houses) remains intact

  •