Attention Flashcards
What is the use of attention
- It is important to study and improve as William James pointed out, attention is so fundamental to our daily lives that sharpening it up is bound to spill over into many different areas of everyday life.
- Enables us to find a way through the mass of stimuli present in our environment everyday.
- Improving it can produce incredible abilities, like multitasking the cocktail party effect, and even curtailing the attentional blink.
Define selective attention
The ability to prioritise and attend to some things while ignoring others
Can be either a a goal driven (top-down) control and shaped by learned and evolved priorities or a stimulus driven control (bottom-down)
— Spatial attention is a variation of this which is the selective direction of visual attention toward a location
What is the basic anatomy of attention
Attentional Control: The superior colliculus (midbrain) and pulvinar
- Damage to these areas leads to deficits in the ability to orient overt and covert attention
Areas of the cortex and cortical/subcoritcal areas are also involved as attention affects how sensory info is processed
The major regions of the brain involved in attention are portions of the frontal and parietal lobes and subcortical structures, including parts of the thalamus and the superior colliculi.
Roles
Frontal: maintaining vigilance
Parietal (posterior): orienting in space
Frontoparietal network: reorienting attention
Thalamic: reflexive attention and attentional filtering
Superior Colliculi: saccadic eye movements
How is the neuropsychology of attention studied
- Brain damaged patients
- People who have disorders that result in deficits in attention such as ADHD that affects portions of the brains attention networks
- Investigating syndromes such as unilateral spatial neglect and Balints which can be mapped postmortem and with brain imaging
Describe unilateral spatial neglect
Spatial neglect is caused by lesions, typically strokes, in a number of different cortical and sub-cortical areas. Although acutely both left and right hemisphere lesions can cause neglect, only right hemisphere lesions cause severe and persistent deficits (Stone et al 1993)
Patients may fail to attend to the contralesional side of space, particularly when ipsilesional stimuli are present. The neglect syndrome provides clear evidence for a location-based visual attention system.
- This is shown through the process of extinction which shows that neglect of the left visual field is not a result of blindness as when they are presented with two stimuli, one on either hemifield there is bias to the ipsilesional side.
Patients have reduced arousal and processing speeds as well as an attentional attention bias in the direction of their lesion (right hemisphere lesion would bias attention to the right) so there would be neglect of the left visual field.
BISIACH 1978: Neglect can also impact imagination and memory as attention to parts of recalled images are biased
Define attention
MATLIN (2005): it is the concentration of mental activity.
HOLT et al: the process of concentrating on some feature of the environmental to the possible exclusion of others
What is Balints syndrome
A patient with this syndrome demonstrates 3 deficits:
- SIMULTANAGNOSIA which is difficult perceiving the visual field as a whole scene
- OCULAR APRAXIA: deficit in making eye movements to scan the visual field resulting in difficulty in guiding eye movements voluntarily
- OPTIC APRAXIA: problem in making visually guided hand movements
What do we learn about attention from neglect and balinets syndrome (when attention fails)
Both syndromes involve different brain damaged areas:
Neglect- parietal/posterial and frontal cortex
Balints- bilateral occupitoparietal lesion
- Neglect shows that damage in cortical areas particularly in right hem results in disturbances to spatial attention whilst Balints shows that occipital and parietal damage caused inability to perceive object recognition.
THEREFORE, you can learn about the organisation of the brains attention system by assessing which attentional/behavioural deficits occur
2. BROOKS 2014 - Right hemisphere appears to be more dominant for SPATIAL ATTENTION - shown by pseduoneglect where normal people show a leftward bias on some spatial attention tasks. Greyscale tasks (asking ppts to choose which scale is darker though they both are fairly similar) force a choice by participants and ppts show a leftward bias. The fact that right-parietal-lobe-impaired patients (unilateral spatial neglect) cannot freely direct attention to the left side of space supports these findings. And the fact that normal people show leftward bias, it suggests that right hem is more dominant for attention and directs attention leftward
- Neglect also shows the competitiveness in selective attention of sensory stimuli: the phenomenon of extinction in neglect patients where they fail to see stimuli when they are simultaneously presented suggests that sensory inputs are competitive as when two stimuli are present simultaneously they compete for attention and the one in the ipsilesional hemifield will will and reach awareness
- Provides further understanding of attentional control networks. MESLAUM (1981) suggested that neglect is a result of damage to the brains attentional networks not due to damage to brain areas + CORBETTA (2002) who found that areas of neglect tend to correspond to the attention network areas.
- Neglect patients are impaired in reorienting to unexpected events (Posner et al 1984). Patients showed especially large deficits in detecting contralesional targets when they were expecting an ipsilesional target, suggesting a deficit in disengaging attention from the ipsilesional field.
Describe the different types of selective attention
VOLUNTARY: Intentionally allocating our processing capacity to something (top-down, goal-directed)
vs.
REFLEXIVE: A sensory event captures our attention (bottom-up, stimulus-driven)
OVERT:
vs.
COVERT: attention that can change spatially without any accompanying eye movements.
Describe the cocktail party effect
Carefully listening to what someone is saying while ignoring other conversations in a room.
CHERRY (1953): describes the ability to attend to one convo among many and the almost immediate attention switch by mentioning a salient word like your name
– Evidence:
CHERRY 1958: Using dichotic listening, he played competing speech inputs through headphones to the two ears of his ppts. Cherry instructed participants to “shadow,” that is, to follow and repeat as rapidly as possible one stream of speech input and to ignore the other. Cherry found that ppts had no memory of what was played in the unattended ear; in fact, they did not even notice if the unat- tended message switched to another language or if the message was played back- ward. They did, however, notice whether the sex of the speaker was different or whether the speech became a pure tone.
Describe the early filter model of attention
Broadbent (1958) argued that information from al the stimuli present at any time enters a sensory buffer. One of the inputs is then selected on the basis of its physical characteristics for further processing by being allowed to pass through a filter. Since we have only a limited capacity to process information, this filter is designed to prevent the information processing system from being overloaded. The inputs not initially selected by the filter remain briefly in the sensory buffer, and if they are not processed they decay rapidly. Broadbent assumed that the filter rejected the non-
shadowed or unattended message at an early stage of processing.
BUT TOO ALL OR NOTHING SO…
TRIESMANS ATTENTUATION MODEL (1964)
claims that instead of a filter which barred unattended inputs from ever entering awareness, it was a process of attenuation, thus the attenuation of unattended stimulus would make it difficult, but not impossible to exact meaningful context from irrelevant inputs, so long as stimuli possessed sufficient “ strength “ after attenuation to make it through a hierarchical analyzation process
Describe late selection models
All information is processed perceptually to determine both physical characteristics and semantic content
DEUSTCHx2 1963:
1. assumes that selection of stimuli happens at level of memory, so later than filter models
2. all stimuli are processed for meaning and are assigned corresponding representations based on previously stored knowledge
3. predicts that unattended stimuli still has an effect on behaviour even if person is not aware of it
Stimulus features are selected via their physical properties. Attended and unattended information passes through the filter to a second stage of selection on the basis of semantic characteristics or message content. Items which are selected areincorporated into short term memory and awareness. It is the second selection mechanism rather than the filter that decides what information gains our awareness. An evaluation is that allstimulus, including those deemed irrelevant, are processed fully.
What is most research on neural understanding of attention focused on
Visual attention as most of the experiments are focused on the visual system
Describe cuing paradigm tasks (methodology)
A neuropsychological test often used to assess attention and an individual’s ability to perform an attentional shift.
Observers are seated in front of a computer screen and are instructed to fixate at a central point on the screen. To the left and the right of the point are two boxes.
For a brief period, a cue is presented on the screen. Following a brief interval after the cue is removed, a target stimulus, usually a shape, appears in either the left or right box. The observer must respond to the target immediately after detecting it. To measure reaction time (RT), a response mechanism is placed in front of the observer which is pressed upon detection of a target.
ENDOGENOUS CUING TASK
The ppts are told that a cue may come up such as an arrow that indicates the mostly likely direction of the target stimuli. So, the orienting of attention is driven by ppts voluntary compliance and meaning of cue.
EXOGENOUS CUING TASK
is the opposite when they base their orientation of attention due to the cues physical features such as colour which makes the reflexivly shift
Describe what neuroscience has shown about voluntary spatial attention
SPATIAL ATTENTION INFLUENCES VISUAL PROCESSING - attended stimuli produces greater neural response than ignored stimuli as observed in multiple visual cortical regions; When attention is directed to a location in the visual field, sensitivity to stimuli at that location in the visual cortex is increased
Although no clear evidence has yet been presented for early modulation of V1 activity with attention in humans, the short latency of the extrastriate P1 effect (onset at 70–80 ms) suggests that spatial attention first affects visual processing at a level not far above V1 and perhaps as early as V2
Attentions effect of modulation of perceptual processing, does not occur until a significant amount of early sensory analysis has taken place where the P1 sensory wave is generated by neural activity in the visual cortex. Suggests that its sensitivity to spatial attention supports early selection models of attention.
- Spatial attention modulates activity in multiple cortical visual areas - Hopfinger 2000 using event-related fMRI showed areas of activation in the visual cortex after attention to one visual hemispheld
- MORAN and DESIMONE (1985) Investigated how visuospatial attention affected neural firing rates in the visual cortex’s of monkeys (previously trained monkeys to fixate on central point and covertly shift attention to stimuli in one visual field). Tested the neural activity effects when monkey shifted attention between two stimuli, one preferred (red rectangle) and one non-proffered (green rectangle) located differently.
Found that visual spatial attention modulates activity of neurons in ventral stream area, particularly the V4 (V4 is one of the visual areas in the extrastriate visual cortex) neuron activity is lower when the effective sensory stimulus (red rectangle) is not attended too, even when it falls within the cell’s receptive field. SO spatial selective attention affected the firing rates of neutrons in the V4
STUDIES ON HUMANS SHOWN ACTIVITY IN MULTIPLE REGIONS OF VISUAL CORTEX
3. TOOTELL+DALE 1998: found that when ppts were asked to visual attend to stimuli located in one visual field while ignoring those in other quadrants, spatial attention produced robust modulations of activity in multiple extra striate visual cortex areas including the V1 - suggesting early processing of attention
- BUFFALO 2012 found that neuronal responses were enhanced by spatially selective attention all along the ventral stream, but these effects were earlier and larger in V4 and progressively later and smaller in V2 and V1. The results in all three areas were obtained in the same monkeys performing the same task, which minimized the variance due to task and monkey variables. The results thus support the idea of a “backwards” progression of attentional feedback within the ventral stream.
