Attention and Visual Search Flashcards
what is attention?
reduces the information overload of sensory stimuli to the brain, to determine perception
inattentional blindness
very salient things in the environment can be missed
what does inattentional blindness suggest?
attention is a distributable and limited resource, as participants were less likely to see the object during a difficult primary task
change blindness
failing to notice major changes in the environment
central capacity theory
there is a single pool of limited resources to distribute across tasks
when tasks exceed the total resource, dual task costs emerge
attentional blink
something can be made invisible by presenting it very quickly following another important stimulus
inference theory
T1, T2, and their masks are encoded into a temporal buffer which takes up items in short-term memory
what are N400 ERPs used for?
to mark whether the brain processes meaning
used to study if T2 is processed without conscious experience
unified theory
increased attention is required to process T1, leaving T2 vulnerable to decay and interference
what is the cocktail party problem?
found unattended auditory information is processed to a lower level of complexity than attended information
1/3 of participants report hearing their name in the unattended ear
bottom-up processing in CPP
dichotic listening is easier when voices are physically different
top-down processing in CPP
familiar voices are easier to pay attention to and ignore
stages of attention as early selection
- parallel inputs enter the sensory system
- these are filtered by physical characteristics
- filtering prevents overloading the limited capacity mechanism
- remaining inputs are available for later semantic processing
attention as early selection
broadbent believes attention occurs during early low-level visual processing
evidence to support early selection
unattended stimuli only undergo limited processing, and inputs are filtered by physical characteristics
evidence to dispute early selection
some of the unattended stream is processed semantically (hearing name) and unconscious stimuli (blindsight, T2) can alter behaviour
attention as late selection
deutsch and deutsch believe all stimuli are processed up to the point of meaning, and the most relevant stimulus determines what response is made
evidence to dispute late selection
ERPs are smaller for unattended stimuli, showing attention must occur at an earlier stage
stages of attention as flexible selection
- unattended information is filtered after the sensory register
- stimulus analysis occurs through a hierarchy of physical characteristics up to semantic meaning
- when capacity is reached, tests are precluded for all but the attended stimulus
posner cueing paradigm
sighted people can pay attention to a part of space they are not directly looking at
(covert attention)
endogenous cues
top-down, goal driven
exogenous cues
bottom-down, stimulus driven
endogenous attention
choosing to pay attention to a particular part of space makes you react faster to things that happen in that part of space
exogenous attention
the same is true, but only if something happens in that part of space very quickly after attention is shifted to it
what is endogenous attention controlled by?
intentions and expectations
- dorsal/parietal regions
what is exogenous attention controlled by?
automatic shifts of attention when peripheral cues are presented
- ventral/parietal/frontal regions
feature search
the target has unique features not shared by other items in the display, in order to pop out
conjunction search
the target has a unique combination of features
reaction time for feature search versus conjunction search
significantly higher for conjunction search when there are more distractors
remains stable in feature search
- can be explained by feature integration theory
feature integration theory
perceptual features are encoded in parallel prior to attention, meaning unique perceptual objects may be detected without the need for attention
what is required to serially search all objects in FIT?
spatial attention
what does FIT believe?
an object is an object only if you pay attention to it
stages of FIT visual search
- rapid initial parallel process to identify features without attention
- slow, serial process to form objects by combining features
illusory conjunctions
experiencing shapes that are the combination of others they did not pay attention to
evidence against FIT
negative priming tasks
negative priming tasks
show semantic processing of unattended stimuli and altered reactions to subsequent stimuli
guided search theory (dual path model)
explains visual search in the real world by using top-down knowledge to narrow down the environment
what does GST believe?
early parallel processing and late serial attentive processing are mixed to produce an activation map
what follows the activation map?
different parts of the scene are weighed based on how promising they are, and objects with the highest activation receive the most attention
