4- Attention

Question 1

What is attention?

Answer 1

Attention is the process by which certain information is selected for further
processing and other information is discarded.
Attentional processes lie at the interface between the external environment and our internal states (goals, expectations and so on).

Question 2

Attention can be driven by the environment - what is this system called?

Answer 2

Stimulus-evoked attentional system- our attention is being grabbed, so-called “bottom-up”. This is unconscious/automatic. Can be due to unusual noises, smells, etc.

Question 3

Attention can be driven by our goals- what is this system called?

Answer 3

Goal-evoked system- our attention is being sustained, so-called “top-down”. This is conscious selection of sensory input/actions. Used in activities requiring extended focus e.g. concentrating on speech in a second language or driving on a dark, wet road when tired.

Question 4

Attention is not a single process but instead 3 networks of distributed anatomical areas associated with different attentional processes. What are these 3 networks/levels of attention?

Answer 4

1. Alerting network- readiness
2. Orienting network- Location
3. Executive control network - reaction/response

Question 5

How do we know these 3 levels of attention are distinct?

Answer 5

There is low correlations between performance on three levels

Different neurotransmitters involved in the different systems- noradrenaline in alerting and acetylcholine in orienting

Question 6

Alerting networks- Arousal, tonic alertness, circadian rhythms

Answer 6

Arousal= readiness to detect stimulus
Tonic alertness= a baseline level of attention that enables a person to remain aware and responsive to their environment for long durations
Circadian rhythms= are natural, internal processes that regulate the sleep-wake cycle. Longest reaction times early in the morning, get gradually more alert as day goes on. Associated with diurnal changes, body temp, cortisol secretion.

Question 7

What is level of arousal regulated by and where is this located?

Answer 7

Level of arousal regulated by reticular formation which is located in brainstem- medulla, pons, midbrain. This is not happening in our consciousness.
Controls sleeping/wakefulness, levels of arousal through neurotransmitter projections.

Question 8

Noradrenaline is the neurotransmitter in alertness. State effects of noradrenaline

Answer 8

In sympathetic nervous system:
Increased HR, BP.
Widening of pupils
Widening of air passages
Narrowing of blood vessels in non-essential organs. In the extreme, this is ‘fight or flight’ response.

In central nervous system:
This is increased alertness/vigilance

Question 9

(alertness) Where is noradrenaline network?

Answer 9

Locus Coeruleus- nucleus in pons produces noradrenaline. Projections from here to other brain areas. Particularly interior frontal, inferior parietal lobe and anterior cingulate.
Activation broadly correlates with vigilance and reaction speed.

Question 10

what is inattentional blindness?

Answer 10

A failure to be aware of a
visual stimulus because
attention is directed away
from it.

Question 11

What is change blindness?

Answer 11

A failure to notice the appearance/disappearance
of objects between two alternating images. These examples reflect the capacity limitations in our processing sytems rather than a fundamental limitation on vision.

Question 12

What is perception?

Answer 12

The incoming information that attention selects from. Ultimately forms the content of awareness.
Regions involved in perception e.g. visual ventral stream.

Question 13

What is awareness?

Answer 13

An outcome (a conscious state) of perceived stimuli that pass through attentional filter

Question 14

Relationship between attention and awareness derived from studies contrasting conscious and unconscious perception. Findings:

Answer 14

Greater activity in regions involved in perception (e.g. visual ventral stream) when participants are aware of stimulus vs unaware.
There is spread of activity to distant brain regions (frontoparietal network) in aware state.

Question 15

Moving the focus of attention is called orienting. What is the difference between covert and overt orienting?

Answer 15

Covert orienting= moving attention without moving the eyes or head
Overt orienting= moving the eyes or head along with focus of attention.

Question 16

Posner’s case study to illustrate that attention operates on a spatial basis:

Answer 16

The ‘attentional spotlight’ is attracted by a sudden change in the periphery- thus attention is externally guided and bottom up- referred to as exogenous orienting.

Question 17

What is endogenous orientating?

Answer 17

Attention is guided by the goals of the perciever. E.g. presented with words and varied instructipn “focus on the central letter” or “focus on the whole word”. Faster judgements about all letters when focussing on whole word.

Question 18

Another paradigm that uses endogenous attention is called visual search, what is this?

Answer 18

Participants asked to detect the presence/absence of a specified target object e.g. the letter F in an array of other distracting objects. It is a mix of bottom-up processing (perceptual identification of objects/features) and top-down processing (holding in mind the target and endogenously driven
orienting of attention).

Question 19

What is attentional blink?

Answer 19

An inability to report a target stimulus if it appears too soon after another target stimulus

Question 20

What is the role of the ventral route in attention?

Answer 20

Ventral route is the “what” pathway, leading into the temporal lobes and is concerned with identifying objects.

Question 21

What is the role of the dorsal pathway in attention?

Answer 21

The dorsal route is the “where” pathway that leads to the parietal lobes. It guides action towards objects. Important for spatial orientating.

Question 22

An area in the parietal lobe called the LATERAL INTRAPARIETAL AREA is involved in attention- explain how.

Answer 22

This area responds to external stimuli (vision/sound), usually unexpected stimuli and is important for eliciting a particular kind of motor response. It contains neurones that respond to salient stimuli in the environment and are used to plan eye movements.

Question 23

What is pseudo-neglect?

Answer 23

PSEUDO-NEGLECT= In a non-lesioned brain over-attention to the left side of space. For example, there is a general tendency for everyone to bisect lines more to the left of centre.

The right-parietal lobes considered to have more dominant role in spatial attention, therefore right hemisphere lesions have severe spatial attention consequences particularly for the left of space.

Question 24

What is hemispatial neglect?

Answer 24

A failure to attend to
stimuli on the opposite
side of space to a brain
lesion. Often associated with legions to right posterior parietal lobe.

Question 25

It is proposed that the left and right parietal lobes have different roles in non-spatial attention- what are these roles?

Answer 25

the right hemisphere is considered important for attending to a salient stimulus the left hemisphere is important for suppressing a non-salient stimulus or “ignoring the elephant in the room”

Question 26

Theories of attention: The feature Integration theory (FIT; Treisman et al)

Answer 26

FIT is a model of how attention selects perceptual objects and binds the different features of those objects (e.g. colour and shape) into a reportable experience. According to FIT, when a target is defined by a conjunction of features e.g. Blue letter H, search becomes slower when there are more items because the items are searched serially. Evidence has come from visual search paradigm: If an object does not share features with other objects in the array it appears to "pop out". When there is a number of distractors, each candidate object must be serially inspected in turn.

Question 27

Feature Integration Theory is an example of EARLY SELECTION model of attention. What does this mean? Contrast with late selection model.

Answer 27

According to early selection theories, information is selected according to perceptual attributes (e.g., color or pitch). Late selection theories assume all incoming information is processed up to the level of meaning (semantics) before being selected for further processing.

Question 28

An example of late selection is negative priming effect- what is this?

Answer 28

If an ignored object suddenly becomes the attended object, then participants are slower at processing it.

Question 29

Theories of attention: Biased competition theory

Answer 29

It explicitly rejects a spotlight metaphor of attention (inherent in FIT). Attention is not a dedicated module in the brain, but a wide set of mechanisms for reducing many inputs to limited outcomes.

Question 30

The biased competition theory explains why damage to the parietal lobe can also lead to extinction. What is this?

Answer 30

In the context of attention, unawareness of a stimulus in the presence of competing stimuli. Patients with right parietal lobe lesions may fail to notice the stimulus on the left when two stimuli are briefly shown (called extinction), but notice it when it is shown in isolation. It suggests that attention depends on competition between stimuli. In competition: Ipsilateral filed to lesion wins, contralateral side perceived in the absence of competition.

Question 31

Theories of attention: the premotor theory of attention

Answer 31

The premotor theory of attention assumes that the orienting of attention is nothing more than the preparation of motor actions- primarily a theory of spatial attention

Question 32

Consequences of Balint's syndrome

Answer 32

Damage to both L+R parietal lobes, severe spatial disturbances. May only notice one object at a time (simultanagnosia). Optic ataxia (using vision to guide hand movements e.g. inability to reach towards object being focused on despite the object being perceived and movement being initiated) Optic apraxia (fail to make appropriate eye movements, problems with changing focus to new object)

Question 33

Illusory conjunctions

Answer 33

A situation in which visual features of two different objects are incorrectly perceived as being associated with a single object.

Question 34

Hemispatial neglect is failure to attend to stimuli on opposite side of space to their lesion. How do we test hemispatial neglect?

Answer 34

Copying or drawing from memory- patients tend to omit features on the left Line bisection- patients tend to misplace the centre of the line towards the right Cancellation tasks- patient must search for targets in an array, striking through them once found.

Question 35

How is hemispatial neglect different from hemianopia (a primary visual field deficit)?

Answer 35

Person with hemianopia searches for things that should be there, can take in full visual scene by moving eyes and head to orientate. Person with hemispatial neglect: Does not search for things that should be there. Lack of awareness of half of allocentric space. Even mental representation. Not a sharp and absolute border between neglected and non-neglected space.

Question 36

Representational neglect

Answer 36

Bisiach and Luzzatti (1978) established that neglect can occur for spatial mental images and not just for spatial representations derived directly from perception. Patients were asked to imagine standing in and facing a particular location in a town square that was familiar to them (the Piazza del Duomo, in Milan; Figure 9.23). They were then asked to describe the buildings that they saw in their “mind’s eye.” The patients often failed to mention buildings in the square to the left of the Duomo.

Question 37

What is double dissociation?

Answer 37

Double Dissociation is when two related mental processes are shown to function independently of each other.

Question 38

Within objects (object-based) vs between objects (space-based) neglect in regards to reading words.

Answer 38

Patients with left object based neglect may make letter substitution errors in reading words and nonwords (e.g., reading “home” as “come”), whereas patients with space-based (or between object) neglect may read individual words correctly but fail to read whole words on the left of a page. Neglect within objects linked to brain damage in ventral stream.

Question 39

Is neglect a disorder of attention or perception

Answer 39

Although the main symptom of neglect is lack of awareness of perceptual stimuli, neglect is best characterized as a disorder of attention rather than perception. WHY? - It tends to be multisensory in nature - The deficit is more pronounced when demands on attention are high (e.g., voluntary orienting, presence of competing stimuli) - There is evidence that neglected stimuli are perceived (albeit unconsciously and perhaps less detailed).

Question 40

Orienting disorder- What is extinction?

Answer 40

Neglect only when there is a competing stimuli. E.g. two things held up. Cannot perceive similar stimuli simultaneously

Question 41

Orienting disorder- Agnosia. What is visual agnosia?

Answer 41

Inability to recognise objects due to damage to ventral stream. Contrasted with types of agnosia associated with dorsal stream damage- problem attending to objects especially their spatial location.

Question 42

Orienting disorder- what is simultanagnosia?

Answer 42

Focus on single objects one at a time. May cause problems with locomotion e.g patient does not notice object in their path. Associated with bilateral lesions to occipital/parietal junction

Question 43

Executive network of the attention system. What are the two executive networks?

Answer 43

1. Immediate reaction- frontoparietal system: Moment-to-moment tasks, especially pre-frontal cortex. 2. Sustained response plan- cingulo-opercular system, task set maintenance. Primarily involves anterior cingulate cortex and anterior insula.

Question 44

Disorders of executive control network/ attentional disorders. These can be acquired (stroke, head injury) and can be developmental (ADHD). Give features of attentional disorders seen in clinical testing:

Answer 44

Distractibility- "name as many animals as you can..."...... "dog, lion, circus, drum, bell, wedding" Perseveration/inertia/obsessive behaviour- Failure to switch in response to chnaging demands "name as many animals as you can" dog, cat, cow, horse… "Now name some types of furniture" sheep, goat, chicken…

Question 45

Primary symptoms of ADHD

Answer 45

Distractibility Hyperactivity Impulsivity Associated with reduced activity in prefrontal cortex- reduced activity of dopamine and noradrenaline. (lasting more than 6 months with normal intelligence and disruption to school performance) The diagnosis is difficult before 6 years

Question 46

What are causal factors of ADHD?

Answer 46

Biological factors (biological parents) Environmental influences e.g prenatal alcohol exposure.

Question 47

ADHD and the prefrontal cortex

Answer 47

Delayed myelination in prefrontal cortex for ADHD. Plus, depletion of neurotransmitter dopamine

Question 48

Inhibitory control in ADHD

Answer 48

Global deficits of tests of attention/executive function. Poorer performance for tests of sustained attention and suppression of prepotent responses. Poorer performance on Go/No go tasks due to reduced prefrontal activation.