M2 Lecture 13: Feb 26 Flashcards
what is Stimulus onset asynchrony (SOA):
The time between the onset of one stimulus and the onset of another
do endogenous cues take more time than exogenous cues to attract attention
yes
Amongst endogenous cues, what works best
gaze and arrows work best (bottom – up?).
what is the Spotlight” model of attention:
Attention is restricted in space and moves from one point to the next. Areas within the spotlight receive extra processing.
what is Visual search:
Looking for a target in a display containing distracting elements.
e.g., Finding the remote control!
what are the elements in Visual search
Target:
Distractor:
Set size:
what is target
The goal of a visual search
what is Distractor
In visual search, any stimulus other than the target.
what is Set size
The number of items in a visual search display.
what are the types of Visual search
Feature search Conjunction search Parallel Serial self-terminating search Guided search:
what is Feature search:
Search for a target defined by a single attribute, such as a salient color or orientation.
what is Conjunction search:
Search for a target defined by the presence of two or more attributes.
The efficiency of visual search is what
the average increase in RT for each item added to the display.
Measured in terms of search slope, or ms/item. The larger the search slope (more ms/item), the less efficient the search.
what is Parallel:
In visual attention, referring to the processing of multiple stimuli at the same time.
what is Serial self-terminating search:
A search from item to item, ending when a target is found.
In real-world searches, what guide visual search
basic features
what is Guided search:
Attention is restricted to a subset of possible items based on information about the item’s basic features (e.g., color or shape).
Ex.: where are the tomatoes?
what is Scene-based guidance:
Information in our understanding of scenes that helps us find specific objects in scenes.
Ex.: where is the faucet? (you know to look near the sink)
what is Feature integration theory
Treisman’s theory of visual attention, which holds that a limited set of basic features can be processed in parallel preattentively, but that other properties, including the correct binding of features to objects, require attention.
what is Preattentive stage:
The processing of a stimulus that occurs before selective attention is deployed to that stimulus
what is Rapid serial visual presentation (RSVP):
An experimental procedure in which stimuli appear in a stream at one location (typically the point of fixation) at a rapid rate (typically about eight per second).
RSVP is used to study what
the temporal dynamics of visual attention
what is Attentional blink:
The difficulty in perceiving and responding to the second of two target stimuli amid a RSVP stream of distracting stimuli.
The second target is often missed if it appears when
within 200 to 500 ms of the first target
what is Nonselective pathway:
Contributes information about the distribution of features across a scene as well as information about the “gist” of the scene. This pathway does not pass through the bottleneck of attention.
what is Selective pathway:
Permits the recognition of one or a very few objects at a time. This pathway passes through the bottleneck of selective attention.
The nonselective pathway computes what
ensemble statistics.
what are Ensemble statistics:
The average and distribution of properties, such as orientation or color, over a set of objects or a region in a scene.
The nonselective pathway computes what
scene gist and layout very quickly
what is Spatial layout:
The description of the structure of a scene (e.g., enclosed, open, rough, smooth) without reference to the identity of specific objects in the scene
is Memory for objects and scenes good
amazingly good and bad
can tell what something is/whereit is but if you remove one small/large aspect it often occurs inching blindness
what is Change blindness:
The failure to notice a change between two scenes.
when can changes pass unnoticed
If the change does not alter the gist, or meaning, of the scene, quite large changes can pass unnoticed
Demonstrates that we don’t encode and remember as much of the world as we might think we do
what are some Disorders of attention
Visual-field defect: Neglect:
Extinction
what is Visual-field defect:
A portion of the visual field with no vision or with abnormal vision, typically resulting from damage to the visual nervous system (occipital lobe).
what is Neglect:
Damage to the parietal lobe can cause a visual field defect such that one side of the world is not attended to.
-> Typically, neglect of the left visual field after damage to the right parietal lobe
Evidence from neglect patients indicates that they sometimes neglect one side of an object rather than one side of the visual field.
what is Extinction:
In visual attention, the inability to perceive a stimulus to one side of the point of fixation (e.g., to the right) in the presence of another stimulus, typically in a comparable position in the other visual field (e.g., on the left side).
Monkeys are trained to attend to either the red or blue bar while keeping their eyes on the fixation point.
Experimenter is recording from a neuron in V4 that preferentially responds to the red bar (the response properties of the neuron were established before the experiment).
The responses of that neuron are higher when what
the monkey is paying attention to the red bar vs. the blue bar
Attention facilitates what
the neural processing of attended stimuli
Participants are asked to pay attention to streams of letters displayed in the left or right visual field, while maintaining their eyes on a central fixation point.
When the letter «L» or «R» appears, participants have to re-direct their attention to the left or to the right.
Activity where is enhanced
in the controlateral visual cortex is enhanced by attention.
The posterior parietal cortex (PCC) controls shifts inwhat
spatial attention
explain the experiment done with monkeys that explains The posterior parietal cortex (PCC) controls shifts in spatial attention
- Monkeys have their eyes on a central fixation point.
- An object appears in the neuron’s receptive field.
- Depending on the condition, mokeys either have to ignore the object, or pay attention to it (saccade, hand reach, no overt movement).
- The PCC neurons fires when attention is redirected towards the neuron receptive field.
