26 Visual Attention Flashcards
Overt versus covert shifts of attention
overt shifts of attention involve movement of the eyes
however, attention can be redirected in the absence of an eye movement (i.e covertly)
Experiment: Event-Related potential (ERP) in neurologically-healthy adults: effects of covert attention on activity in the occipital lobe. What was its conclusion?
task participants fixate on the centre while stimuli are flashed at either the left or right location. During separate blocks, participants are asked to COVERTLY attend to either the left or right location while maintaining fixation on the centre.
Results: A stronger neural signal occurred in response to the stimulus when attention was directed at the location of the stimulus
Conclusion: Modulation of neural activity is consistent with the idea that selective attention to one part of the visual field comes at the cost of neglecting the other parts
The figure attached illustrates the neural signal recorded from the right occipital lobe in response to a visual stimulus in the left hemifield when attention was either directed at the stimulus (left half of figure) or directed elsewhere (right half of the figure).
Exogenous vs endogenous movements of attention
The ERP study measures neural changes associated with the attention that was directed voluntarily
As with eye movements, attention can also be shifted reflexively in response to a sudden change in the periphery
Exogenous shifts of attention are elicited by an external stimulus (i.e reflexively) the SC is important for reflexive movements of attention.
Endogenous shifts of attention are elicited internally (i.e. voluntarily). Cortical neurons are important for voluntary movements of attention.
What is attention facilitates responses?
When attention is directed towards a location and then a target appears shortly afterward, the latency to response to that target is reduced when the target appears at the location of attention compared to when the target appares at a different location.
What is inhibition of return?
Wehn attention is directed toward aa location, and then there is a long delay before the target appears, the latency to response to that target is increased when the target appears at the attention location compared to when the target appears at a different location.
Inhibition of return is though to facilitate efficient visual search by discouraging orientation toward recently attended locations.
Research indicates that stronger inhibition of return is associated with better driving performance
Inhibtion of return provides an example of a reflexive mechanism of attention
What is the flanker task? and flanker effect
The flanker task can be used to assess the efficacy of strategic control over attention (i.e., how easily distracted the participant is).
Instructions: maintain fixation on the centre of the screen. When a stimulus appears at centre, indicate its identity by pressing the appropriate button as quickly as you can (but try not to make mistakes)
Flanker effect = FTs on incongruetnt trials minmus RTs on congruent trials.
Age and driving performance
aging is associated with worse driving performance
age-related increases in distractibility may be one factor that underlies age-related deficits in driving performance.
what is overt attention?
shift of attention involve movement of the eyes
What is covertly moving attention?
attention can be redirected in the absence of an eye movement.
