NEURO2020 LEC 8

ATTENTION

Processes enabling the recruitment of resources for processing selected aspects of incoming sensory information more fully than non-selected aspects. 

ATTENTION COMPONENTS

• Recruitment of resources 

• Focussing them on selected aspects of sensory inputs 

ATTENTION CONCEPTS

• Selectivity (spatial, auditory, timing) 

• Capacity 

• Expectation 

• Switching 

CAPACITY

Is the amount of perceptual resources that are available for a given task or process 

• Varies with task and individual 

SELECTIVITY

The fixed perceptual resources can be allocated to different subsets of information in a flexible way 

• Is not selective in terms of what gets processed and what does not 

• Ex. Overt attention (where your eyes are looking), covert attention (where you are attending to) 

VISUAL SPATIAL ATTENTION - SHIFTING ATTENTION

• Disengagement 

  • to move attention, it must first disengage from its current target 

    • Damage to the parietal lobe results in deficits 

• Movement 

  • Once disengaged, attention is free to move and must be directed to the new target 

  • Damage to the superior colliculus results in deficits 

• Engagement 

  • After reaching the target, attention must be reengaged on the new object 

  • Damage to regions in the thalamus results in deficits  

VISUAL SPATIAL ATTENTION - SPOTLIGHT + ZOOM LENS

Spotlight 

• Illuminates objects in its focus region 

• Increased speed of attention if cued  

• Concentrate resources on selected regions of space 

Zoom lens 

• Focus = narrow field = finer resolution = better attention 

ENDOGENEOUS + EXOGENEOUS CUES

Endogenous cues 

• Attention must be voluntarily pushed from central cue to cued location 

• Operates over longer time course 

• Attention lasts longer 

Exogeneous cues 

• Attention is drawn to the location of the cue  

• Usually a flash or movement 

• Can't be ignored (involuntary) 

• Brief attention 

DISTRIBUTED ATTENTION

• Features parallel processing and visual 'pop out' 

• Visual processing occurs simultaneously over the whole visual field 

• Quicker reaction 

FOCUSED ATTENTION

• Features serial processing 

• Visual processing is a series of attentional 'fixations' each covering a different region of the visual field 

• Slower reaction (more distractors) 

NEUROLOGICAL RESEARCH ON VISUAL ATTENTION

Enhancement of processing/amplification of signal from a region of space when attention is deployed there 

FUSIFORM FACE AREA

• In ventral stream of visual pathway 

• Process faces 

PARAHIPPOCAMPAL PLACE AREA

• Close to the hippocampus 

• Responds to places and locations 

HEMI-SPATIAL NEGLECT

• Line bi-section test  

• Clock drawing 

• Eye movements 

• Cancellation task  

Neglect  

• fail to report left field objects

• Visual experience is normal  

• Brain fills in visual field that’s missing 

Extension 

• Inability to disengage attention from particular target  

HEMI SPATIAL NEGLECT PET STUDY

• right hemisphere damage = hemi-spatial neglect in left visual field 

• left hemisphere damage = the right parietal lobe does double duty. It deploys attention to left and right visual fields.  

• Therefore, damage to the right hemisphere is more inhibitive than damage to right  

POSNER CUING PARADIGM

Measures covert spatial attention:

Valid = The cue correctly points to the location where the target appears. (fastest)

Invalid = The cue points to the wrong location. (slower)

Neutral = The cue gives no directional information.

MACK AND ROCK SHOWING UNATTENDED PROCESSING ALLOWS PERCEPTION OF:

Colour and location