Ch. 7-8 Flashcards
attention
any of the very large set of selective processes in the brain; to deal with the impossibility of handling all inputs at once, the nervous system has evolved mechanisms that are able to bias processing to a subset of things, places, ideas, or moments in time
attention can be…
external or internal; overt or covert
external attention
attention to stimuli in the world
internal attention
our ability to attend to one line of thought as opposed to another or to select one response over another
overt attention
directing a sense organ at a stimulus
covert attention
pay attention to something while looking elsewhere
selective attention
the form of attention involved when processing is restricted to a subset of the possible stimuli
reaction time (RT)
a measure of the time from the onset of a stimulus to a response
cue
a stimulus that might indicate where (or what) a subsequent stimulus will be; can be valid (giving correct information), invalid (incorrect), or neutral (uninformative)
exogenous cue
in direction attention, a cue that is located out (exo) at the desired final location at attention
endogenous cue
in directing attention, a cue that is located in (endo) or near the current location of attention
stimulus onset asynchrony (SOA)
the time between the onset of one stimulus and the onset of another
inhibition of return
the relative difficulty in getting attention (or the eyes) to move back to a recently attended (or fixated) location
the spotlight of attention
- attention could be deployed from spot to spot
- might move in a manner analogous to the movements of our eyes
- best evidence suggests that attention is not moving from point to point in the brain in the way a physical spotlight would move across the world
visual search
a search for a target in a display containing distracting elements
target
the goal of a visual search
distractor
in a visual search, any stimulus other than the target
set size
the number of items in a visual display
- it is harder to find a target as the set size increases
to measure the efficiency of a visual search
- often ask how much time is added for each item added to the display
- measures the RT required for the observer to say “yes” if the target is present or “no” if there is no target in the display
feature search
visual search for a target defined by a single attribute, such as a salient color or orientation
salient
the vividness of a stimulus relative to its neighbors
parallel search
visual search in which multiple stimuli are processed at the same time
search is inefficient when…
the target and distractors in a visual search task contain the same basic features
serial self-terminating search
a search from item to item, ending when a target is found
guided search
search in which attention can be restricted to a subset of possible items on the basis of information about the target item’s basic features
conjunction search
search for a target defined by the presence of two or more attributes
prime
a stimulus that might make it easier or faster to respond to a subsequent stimulus
scene-based guidance
information in our understanding of scenes that helps us find specific objects in scenes
anchor objects
typically a relatively big object that provides information about the location of other objects
binding problem
the challenge of tying different attributes of visual stimuli (e.g., color, orientation, motion), which are handled by different brain circuits, to the appropriate object so that we perceive a unified object
feature integration theory
Anne Treisman’s theory of visual attention, which holds that a limited set of basic features can be processed in parallel preattentively, but other properties, including the correct binding features to objects, require attention
preattentive stage
the processing of a stimulus that occurs before selective attention is deployed to that stimulus
- automatic
- feature search
- parallel processing
illusory conjunction
an erroneous combination of two or more features in a visual scene
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 8 per second)
attentional blink (AB)
the tendency not to perceive or respond to the second of two different target stimuli amid a rapid stream of distracting stimuli if the observer has responded to the first target stimulus 200-500 milliseconds before the second stimulus is presented
- fishing with a net analogy
priority map
a hypothetical neural representation of visual space in which the activity at each point reflects how much that location (or object) will attract attention
lateral intraparietal area (LIP)
a brain region, present in both parietal lobes, that serves an important role in the control of visual attention
frontal eye fields (FEF)
brain regions in both frontal lobes that help to coordinate visual selective attention with the movement of the eyes
superior colliculus (SC)
a structure in the midbrain that is important in initiating and guiding eye movements
important candidates for priority maps
LIP, FEF, and SC
fusiform face area (FFA)
a region of extrastriate visual cortex in humans that is specifically and reliably activated by human faces
parahippocampal place area (PPA)
a region of extrastriate visual cortex in humans that is specifically and reliably activated more by images of places than by other stimuli
response enhancement
an effect of attention on the response of a neuron in which the neuron responding to an attended stimulus gives a bigger response
sharper tuning
an effect of attention on the response of a neuron in which the neuron responding to an attended stimulus responds more precisely
- ex. a neuron that responds to lines with orientations from -20 degrees to +20 degrees might shift to respond strongly to -10 to +30 degree lines
different neurons…
perform different parts of the task of attending, and each subtask may require a different type of change in neuronal responses
Reynold’s and Heeger’s “normalization” theory
says that the current response of a neuron is the product of that neuron’s built-in receptive field and the effects of attention; this product must then be “normalized” by neural suppression
complete inattention would be…
something near to functional blindness because one would not be able to recognize objects or find what they are looking for without attention
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; attentional equivalent to a loss of an ability for attention
neglect
in reference to a neurological symptom, in visual attention: 1) the inability to attend or respond to stimuli in the contralesional visual field (typically, the left field after right parietal damage), 2) ignoring half of the body or half of an object
can assess neglect with a “line cancellation test”
- patient is given a piece of paper full of lines and asked to draw an intersecting line through each one
- would cross lines on one side, but those on the other side are overlooked
contralesional field
the visual field on the side opposite a brain lesion