3. External Attention

What is vigilance/alerting?

• signifies achieving and maintaining a state of high sensitivity to incoming stimuli

• involves a change in the internal state of the body & brain in preparation for sensing and processing a stimulus (e.g. changes in heart rate, brain oscillatory activity that serve to inhibit competing activities)

Warning signal in vigilance and alerting?

• phasic response of the system

• Tells us when something will occur and increases the speed of focus on or response to the input signal but not accuracy

• improves how quickly you’re going to respond, speed of sensing

What is the sustained alert state in vigilance and alerting?

• tonic response of the system

• critical for optimal performance in tasks of higher cognitive function

What is the main modulator for alerting?

norepinephrine

What did Posner and Boies find using a cuing task measuring the function of warning?

• main measure is the difference in RT’s between two conditions

• double cue vs no cue

• warning signal, provides information of when but not where the target will appear

What is involved in the continuous performance task - measuring the function of sustaining?

• observers see rapid, random series of single digits or other visual stimuli on a screen

• they are required to press a response key for every digit (go) except a rare, designated digit (no-go)

• the high frequency of “go” trials is intended to create an automatic response pattern, making the inhibition required for the rare “no-go” trials a measure of sustained attention and inhibitory control

What is involved in the alerting mechanism which optimises performance by adaptively adjusting gain (responsivity) or target?

Tonic Alertness

• tonic alertness - sustained signal

• baseline, intrinsic level of wakefulness and arousal maintained over a long period

• enduring and less discriminative increase in gain

• slowly degrades performance within the current task, but it facilitates the disengagement of performance from this task and thereby the sampling of other stimuli

What is involved in the alerting mechanism which optimises performance by adaptively adjusting gain (responsivity) or target?

Phasic Alertness

• warning signal

• momentary, rapid increase in response readiness triggered by an external warning stimulus

• transient, system-wide increase in gain driven by task-related decision processes

• burst of release of norepinephrine

What is alertness very strongly regulated by?

the Locus Coeruleus

What is involved in the process of orienting/focusing attention?

• objects in a visual scene compete for access to visual short-term memory

• this competition is biased by top-down signals that promote access of behaviourally relevant objects

• these top-down signals are characterised as working memory, long-term memory, or action related interact with sensory (bottom-up) signals produced by objects in the visual scene

• these interactions enabling the desired object to be selectively perceived and entered into memory at the expense of unimportant objects

• exogenous and endogenous

What is involved in the process of reorienting/shifting attention?

• objects that are outside the current focus of attention i,e that do not match current settings for selecting stimuli and responses

• these objects we are looking for may appear with different features than we expected or at a different location

• what is more a new object ay appear that requires a completely different course of action

• we may be presented with new events requiring a response while we are engaged in ‘internally directed’ activities that do not involve interaction with the environment

• can happen reflexively, based on their high sensory salience or behavioural relevance

What does orienting and reorienting involve?

• signifies selecting what, when and where to process the input

• involves improving detection, recognition accuracy and response time

• enhances selection in primary sensory cortices

• improving neuronal tuning

• modulating spatial properties of receptive fields

• enhances stimulus discrimination

Which Attentional Network governs orienting?

• dorsal attention network

• sensitive to sensory stimuli based on internal goals or expectations and salient uninformative and unimportant stimulus

Which attentional network govern reorienting?

• ventral attentional network

• optimising the shift

• sensitive to behaviourally relevant stimuli in the environment

What is the main modulator of orienting and reorienting?

acetylcholine

What is involved in spatial-based attention?

• enhances the efficiency and accuracy of processing information within the attended location

• these mechanisms evolved to guide and control eye movements

• attention and eye movements are tightly interlinked

What are some different types of spatial-based attention

• focussed: spotlight

• divided: split across multiple non-contingent locations

• distributed: spread across space

How is focused attention measured?

• RT and accuracy between the no-cue condition vs cue condition

Endogenous spatial cuing

• voluntary

• effect is slower within 300-500 ms

• sustained up to 1200ms

• cue validity dependent

Exogenous spatial cuing

• involuntary

• effect is rapid within 90-120ms

• transient - dissipates after 300ms

What is involved in inhibition of return?

• attention is biased away from a location recently focused, resulting in slower re-attending to that location and faster to notice new things

• spatial cueing can produce parallel facilitatory and inhibitory signals

• responses to subsequent targets may reflect effects arising from the interaction of the two signals during target processing

• good for foraging - stops you from looking at where you just looked before, critical for moving you forward for searching

What is involved in divided attention?

• valid cues much higher accuracy than invalid cues

• across limited by the number of spatial locations

• bigger capacity across hemifields

• middle processing - much less inaccuracy suggests we actually have two spotlights of attention

How does tracking multiple objects across space support divided a

ttention?

• shows observers ability to divide and manage focused attention over several moving points

• limitation to how many we can track. Affected by: speed of movement, density of items

• the limitations are within a hemifield

What did Chong and Treisman find regarding distributed attention?

• pop out search- much more accurate as describing the mean

• ability to have an average across a set of objects

What is involved in feature-based attention?

• not spatially restricted

• selecting a feature leads to global enhancement of features outside the spatial focus of attention

What is shown through the attention capture task demonstrating orienting to high value features?

• A: training task: observers had to say what the orientation of a line was insight a red or green circle, they were rewarded more highly for red circles, less so for green. completed 1008 trials to build up the association between the colours and the chance of reward

• B: Capture task: observers look for unique shape amongst 6 objects. half the time one of the distractor was red or green. So either high value distractor, low value distractor or neither

• high value distractor increased RT on main task

• higher impulsivity and lower WM with higher RT’s for high value distractors

What experiment is used to show object-based attention?

• detection and discrimination task with lines

• whether cued at the top or bottom of the object - just as fast

• shows how attention spreads to all parts of a recognised object

• all features of the attended object are processed faster and more accurately than features of other object

What is involved in time-based attention?

• orienting attention to a specific time point leads to faster reaction times and/or higher accuracy for events occurring at the expected time

• tested using RSVP - attentional blink

• increased blink when the two targets are from different categories

What did Strayer, Drew and Johnstone et al find regarding dividing and sustaining attention while driving?

• simulator setup: a high-fidelity driving simulator was used to create realistic driving conditions, manipulating traffic density (low vs high)

• tasks: ppts drive under single-task (only driving) and dual-task (driving and conversing on a cell phone) conditions

• cell phone conversations divert attention away from driving, impairing both explicit and implicit memory for visual information, slower to break, kept breaking for longer ad took longer to slow down

• BUT in car conversations do not seem to have the same impact: 12% fail task to park in layby compared to 50% with hands free conversation

What was found by Dingus et al in naturalistic driving studies?

• data were collected using advanced instrumentation in participant vehicles, including video cameras and sensors that recorded driving parameters continuously

• capturing data from over 35 million miles driven, 3,500 ppts in 6 US states

• driver related factors (error, impairment, fatigue, distraction) are present in nearly 90% of crashes

• distraction, particularly from handheld electronic devices, is identified as a significant risk factor

What are the differences between focusing narrowly and distributing spatial attention?

Focused

• localise items in a display

• bind the features correctly

• explicitly recognise the object

Distributed

• global image properties - the gist of an image

• summary statistics of a set of items

• disjunctive features

What did Evans, birdwell and wolfe find studying finding cancer when focusing attention?

• 100 cases (50 positive, 50 negative), inserted into the normal workflow

why is the prevalence effect important for the clinic?

• low prevalence causes observers to MISS targets that they would find at high prevalence

• the same effect occurs for trained radiologists engaged in breast cancer screening in the clinic

• perhaps half of routine miss errors may be accounted for by this behavioural effect & we have ideas how to counteract it

Why is the “gist of the abnormal” important in clinical attention research?

t shows how well attention can quickly detect important abnormalities without detailed analysis.

• Helps clinicians spot problems fast

• Reveals attentional or perceptual deficits in patients