The Attending Brain Flashcards
3 properties of attention
Attention can be voluntarily controlled (we can decide where or at what to direct our attention).
Attention is selective (we choose among several alternatives where to attend).
Attention has limited capacity (you can’t process all at once).
Definition of attention
Attention is the process by which certain information is selected for further processing and other information is discarded.
Function of attention
Avoid sensory overload. Optimize the use of cognitive resources available.
Contrast between attention & perception:
Perception is concerned with making sense of the external environment, whereas • Attention lies at the interface between the external environment and our internal states (goals, expectations).
Inattentional blindness
Failure to be aware of a visual stimulus because attention is directed away from it.
Often linked to a filter or ‘bottleneck’ in operation
“invisible gorilla test” experiment,– ( observers were told to count the number of passes or to keep track of the number of throws versus bounce passes – 50% did not notice gorilla)
Change blindness
Failure to notice a change, for example, the appearance/disappearance of objects.
— Simons and Levin (1998) carried out studies in which participants started to have a conversation with a stranger. This stranger was then replaced by a different stranger during a brief interruption (e.g., a large object coming between them).
Many participants simply did not realize that their conversational partner had changed!”
Spotlight metaphor
- Attention tends to be directed to locations in space - Spotlight may move from one location to another, highlighting information.
- It may zoom in or out (narrow or wide “beam”)
What controls the spotlight? How does it know where to go?
Endogenous / exogeonous attention.
You - WHO YOU ARE Endogenous Orienting our ability to intentionally attend to something (top-down or goal-directed or voluntary) Exogenous orienting the ability of a sensory event to capture our attention (bottom-up or stimulus-driven or reflexive attention) What ends up being selected depends on the interaction between these two influences.
Endogenous Orienting
our ability to intentionally attend to something (top-down or goal-directed or voluntary) (Imagine you’ve lost your car keys Now you have a goal and you move around your attention to find the keys)
Exogenous orienting
the ability of a sensory event to capture our attention (bottom-up or stimulus-driven or reflexive attention) (Or attention might be captured by salient or important features in the environment Often loud noises, changes in motion, brightness)
Limitations of the spotlight metaphor
-We can split attention between two non-adjacent locations
- Eye gaze ≠ attention (covert vs. overt attention)
Covert attention
Can report letters at attended location even without looking = Covert attention (Hidden from the observer) still cant report (eg. letters) at other locations
there is a natural tendency for attention and eye fixation to go together because visual acuity (discriminating fine detail) is greatest at the point of fixation. Moving the focus of attention is termed orienting and is conventionally divided into covert orienting (moving attention without moving the eyes or head) and overt orienting (moving the eyes or head along with the focus of attention).
Non-spatial attentional selection
(A limitation of the spotlight metaphor)
Object-based attention Different parts of visual ventral stream (representing different stimulus types/properties increase in activity when attended (ie - ‘faces’= stimulus in ‘fusiform face area’ in the visual ventral stream)
Time-based attention: the ‘attentional blink’, (or inability to report a target stimulus if it appears soon after another target stimulus).
Two Cortical Pathways for Visual Perception
Dorsal (“where/how”) stream (Parietal)
ventral (“what”) stream (Temporal)
Two Cortical Pathways for Visual Perception [dorsal and ventral] - what do they do
Dorsal (“where/how”) stream (Parietal)
- Locating objects in space
- Guiding actions directed at those objects
- Attention (spatial or not) - in conjunction with frontal areas
ventral (“what”) stream (Temporal)
- identifying of objects
- attaching meaning/ significance to them
Lateral Intra-Parietal Area (LIP) - Single cell electrophysiology shows this area encodes…
motor properties (important for saccades)
sensory properties (both sound and vision), enables sounds to be remapped to eye-centred coordinates
Neurons in LIP show remapping of sounds to eye-centred coordinates Example: an LIP neuron responds to a sound coming 20 degrees to the left of the fixation point irrespective of whether the sound source itself comes from the left or center of space (enabling orienting of eyes to sounds.) *relative*
saccade
(/sɨˈkɑːd/ sə-KAHD, French for jerk) is a quick, simultaneous movement of both eyes between two phases of fixation in the same direction.
Spatial attention (LIP)
LIP codes a spatial ‘salience map’ in which only the locations of the most behaviorally relevant stimuli are encoded.
At any given time LIP is ‘selecting’ attention
Salient
Any aspect of a stimulus that, for whatever reason, stands out from the rest.
Lateral Intra-Parietal Area (LIP) is important for attention because:
Important for attention because…
- Doesn’t respond to all* sensory stimuli (sparseness) *or the same stimuli all the time. NOT linked to presence (necessarily) - linked to attention
- Responds more to stimuli that are unexpected such as sudden flash (i.e. important for exogenous attention)
- Responds more to stimuli that are task relevant (i.e. important for endogenous attention) and to current position of the eyes (both needed to plan a saccade).
- Codes a spatial ‘salience map*’ in which only the locations of the most behaviorally relevant stimuli are encoded. *which is selecting attention at any given time
Frontal-Parietal Attention Mechanisms
Corbetta & Schulman (2002) suggested that the dorsal stream should be subdivided into two:
- Dorso-dorsal route (including LIP and “frontal eye field” region) involved in orienting in a salience map (important for endogenous orienting).
- Ventro-dorsal route (involving the “temporoparietal junction (TPJ)” and “ventral prefrontal cortex” (VFC)) acts as a ‘circuit breaker’ (e.g. attentional disengagement from ongoing activity caused by exogenous stimuli)
•Dorso-dorsal route
(including LIP and “frontal eye field” region) involved in orienting in a salience map (important for endogenous orienting).
LIP (lateral intraparietal area) and FEF (frontal eye field)
•Ventro-dorsal route
(involving the “temporoparietal junction” and “ventral prefrontal cortex”) acts as a ‘circuit breaker’ (e.g. attentional disengagement from ongoing activity caused by exogenous stimuli)
TPJ and VFC
* involved in interrupting the current of attention (exogenous)
Hemispheric Differences
(aka lateralization)
Spatial
- Parietal lobes represent full visual field but in a graded fashion (salience map)
- BUT: brain damage in humans to right parietal lobe has more profound effects than damage to left (‘neglect’)
- Possibly right LIP contributes more to salience map (right hemisphere spatial dominance makes left visual field more salient).
