Williams James
Taking the possession by the mind in clear and vivid form of one of several simultaneously possible objects
What does covert include
Central fixation point with peripheral placeholders
Cue - (flash, arrow) indicated where a target will likely appear
Valid cues (correct location) speed up the reaction time
Invalid cues (incorrect location) delay them
Covert vs overt = overt involves moving th eyes (saccades) to a target, covert purely mental (looking out of the corner of eye)
Covert paradigm
Posner cueing task
- measure shifting of attention to a location in the visual field without corresponding eye movements or head turns.
Partcipants maintain central fixation while covertly process if peripheral cues, allowing attentional contorl, brain activity and cogntive mechanisms separate from motor repsonses
Orientating
Exogenous (automatic) - reflexive, fast, bottom-up, attention shift caused by sudden stimulus
Endogenous (voluntary) - slow, top-down, attention directed by voluntary strategic, cogntive effort
Visual attention
Nakayama & Mackaben (1989)
Not a single monolithic process, consistent of two distinct components, sustained components and a transient component
Transient attention - component is triggered by a sudden unexpected stimulus (exogenous cue)
Acts quickly, peaking approximately after onset cue, rapidly declining
Transient attention provides a much larger boost in performance compared to sustained attention alone
Sustained attention - slower to develop, under voluntary contorl, related to prior knowledge of a targets location, sustained high-accuracy performance, doesn’t procure the same repaid boost that eh transient component does.
Spotlight metaphor
Visual atttention works like a spotlight beam in a dark room, highlighting specific stimuli for conscious processing whilst filtering out surrounding, irrelevant information
Focuses on one location at a time, movable and limited, adjustable size to enhance processing efficiency
Attentional network
Neural systems
Dorsal Attentional Network (DAN)
- top down goal driven system , frontoparietal network, manages voluntary, intentional foucs on specific stimuli
Ventral Attention Network (VAN)
- bottom-up, stimulus driven system that handles involuntary attention, detecting unexpected or relevant stimuli in the environment
Three-netwrok model
Alerting - vigilance and arousal, brainstem
orienting - directs attention to specific locations
executive control - revolves conflict among stimuli
Three areas involved in atttention
Posterior partial lobe - Disengage
Superior Coliculus - Move
Pulvinar - enhance
PET and fMRI imaging of the brain has confirmed role of parietal cortex in attention shifting in contorl subjects
Card trick - change blindness
Primary limited attentional capacity, moemory failures, brains tendency to focus only ion a few stimuli at a time
- brief interruptions in the visual fields
- perceptual phenomenon where observers fail to detect significant change in visual scene
Saccades
Rapid eye movements
Change blindness, limited resources
Attention is a limited resources intensely focused on a specific task, brain filters out unimportant, background information, inattentional blindness, failure to see unexpected objects
Subconscious processing - conscious blindness suggest brain may still register information subconsciously
Selective looking
Selective attention showed people only focus on a specific task, fail to perceive unexpected,
neisser and Becklen 1975 - particpanst watched a video where two distinct scenes (basketball game, hand slapping, superimposed on top of each other
Partcipants were asked to follow only one of the scenes , during video unexpected events were added to the unattended scene. Subjects could effectively follow attended event but rarely noticed the unexpected, incongruous events
Star of David
Brawn and Snowden 2000
Investigated object-based attention using a cuing paradigm with two overlapping shapes, to determine how attention is directed to specific objects versus specific locations
Detetcion vs identification = cuing effects were significantly larger when partcipants were required to identify an aspect of a target compared to just detecting its presence
Selection works by sensitising (facilitating) specific spatial locations that are occupied by the attended object
Signal detection theory to confirm that the greater attention effects in discrimination tasks were not merely due to increased task difficulty
Object-based attention process
Malcolm and shomstein 2015, real world scenes rather than just simple laboratory stimuli like rectangles, work established when attwntion is directed to a specific location on an object, perceptual benefits spread across the entire object
Visual system uses object based representations to guide both covert (mental) and overt (eye movement)
