w3 Flashcards
what is attention
a resource that you distribute
why is attention necessary
the amount of information coming down the optic nerve ar exceeds what the brain is capable of fully processing and assimilating into conscious experience
how does attention help the brain to process stimuli
Attention reduces this information overload and determines what we perceive
what is inattentional blindness
We overestimate how
much of the world we are
actually aware of- even very salient (i.e.
attention-capturing) things can be missed
can inattentional blindness be induced in healthy patients?
yes easily
what affects inattentional blindness
- Occurs more frequently if
the display is transparent - Depends on the difficulty
of the task. The more the
primary task occupies
attention, the less likely
they are to see the
gorilla/umbrella
what study provides evidence for inattentional blindness
Simons & Chabris, 1999
- video style either opaque or transparent
- counting task either hard or difficult
- watch teams passing a ball and have to count passes, miss that a gorilla is in the video
what does the central capacity theory suggest
attention is a single central capacity that can be used flexibly, the single pool is shared between multiple tasks
what is the attentional blink
We can make something invisible by
showing it to people very quickly after
showing them something else that is
important to them
key ingredients of the attentional blink:
– Rapid visual stimuli (at ~10 Hz)
– Participants asked to look out for
TWO targets and report if they saw
them at the end of each trial
– The first target is referred to as T1,
and the second target as T2
– Masks (i.e. distractors) need to follow
T1 and T2 for the effect to work
what happens when your brain accesses the meaning of almost any stimulus
we see a negative event-related potential, called the N400
what does the N400 reflect
cognitive processes related to accessing the meaning (semantics) of a stimulus
what can N400 be used for
a sign (or marker) that someone’s brain is processing meaning, without them
telling us with their behaviour
what did Luck (1996) find
even when attentional blink occurred, there was an N400 after T2, meaning it was unconsciously processed
what does interference theory of the AB (Shapiro, 1994) propose
- T1, T2 and their masks are all encoded into a temporal buffer
- The AB is competition for retrieval among all items in short-term
memory
what evidence is there for the interference theory to explain the AB
Isaak (1999) reported that the AB increases with increasing
numbers of task-irrelevant competitors (distractors)
how does a unified model explain the AB
- Due to the mask following T1, increased attention is required to
process T1.
– This leaves less attention for processing of T2, which leaves T2
vulnerable to decay or interference from distracter
what is the cocktail party problem
A familiar voice is easier to pay
attention to AND easier to ignore
what did Cherry (1953) find
Unattended auditory information is processed to a lower level of complexity than attended information
what goes into the sensory register according to Broadbent’s (1958) Theory
parallel input
what happens after input into the sensory register in Broadbent’s (1958) Theory
Inputs are then filtered on the basis of its physical characteristics
– Filtering prevents overloading of the limited capacity mechanism
– Inputs remaining in the buffer after filter are available for later [semantic] processing
who proposed attention as late selection
Deutsch and Deutsch (1967)
what does attention as late selection propose
All stimuli are fully analysed
– The bottleneck occurs late,
before the response
– The most relevant stimulus
determines what response is
made
what does Treisman (1960) leaky filter propose
Unattended information is attenuated/filtered after the sensory
register
what is covert attention
Sighted people can pay attention to a part of space that they aren’t
directly looking at
what does Posner’s endogenous system involve
Controlled by the individual’s intentions and expectations
Involved when central cues are presented
Top-down
what does Posner’s exogenous system involve
Automatically shifts attention
Involved when uninformative peripheral cues are presented
Stimuli that are salient or that differ from other stimuli are most likely to be attended
Bottom-up
what does attention as a spotlight mean
Endogenous attention is a limited
resource that we distribute
what is feature search
Target has a unique feature that is not shared by other items in the display
what is conjunction search
Target has no unique feature that is not shared by other items in the display, making visual search more difficult
when is reaction time slowest
many distractors, conjunction search
what did the feature integration theory say
- Perceptual features are encoded in
parallel and prior to attention - If an object has a unique perceptual
feature then it may be detected
without the need for attention - If an object shares features with other
objects, then it cannot be detected from a single perceptual feature and spatial attention is needed to search all candidates serially
what are the stages of visual search according to feature integration theory
- object in front of you
- pre-attentive processing of visual features
- focused attention to bind features
- perception of object
what are illusory conjunctions according to FIT
When focused attention is absent
what evidence is there against FIT
FIT argues that an object is only an object if it is attended to, however negative priming shows semantic processing of unattended stimuli
strengths of FIT
- An important contribution to
explaining what happens within the
attentional spotlight - Influenced thinking on a variety of
topics from early sensory encoding to
later attentional control
weaknesses of FIT
- Doesn’t explain why the similarity of
distractors is influential - Neglect/Extinction patients have
problems with both conjunctive and
single-feature targets
what does guided search theory suggest about real world search
- In real world search,
people usually have
expectations of where to
find certain things - Prior knowledge can make
search more efficient
how does guided search theory differ from FIT
Unlike FIT, where processing moves from parallel (pre-attentive) to serial (attentive), Wolfe (1998) assumes a simultaneous mix of serial and parallel strategies for visual search
according to guided search theory, what do early pre-attentive processes produce
an activation map, where each item in the
display has its own level of activation
other name for guided search theory
dual path model
is dual path model top-down or bottom-up
Combines top-down and bottom-up
processing for efficient search
