Active Vision and Attention Flashcards
What is attention?
Attention is the selection of a particular sensory stimulus or mental process and selects for specific further analysis
What is arousal? What is its difference from Attention?
Arousal represents a global state of the brain e.g if someone is awake or asleep, individuals who are awake can operate at different levels of arousal or alertness. Attention is selectively focused, which makes it different from arousal.
What are the models of early and late selection? Where in the brain are they associated with?
Models of early selection suggest that there is a “low-level gating mechanism” that attenuates the irrelevant information prior to the completion of full sensory and perceptual analysis
Models of late selection suggest that all stimuli are processed via sensory and other processing prior to any actual selection
These early and late selection stages tend to refer to processing stages - in that basic sensory analyses are presumably conducted early on in the processing sequence. The more complex analysis doesn’t come until later.
Early processing: brainstem analysis and lower-level sensory cortices
Late processing: higher-level association cortices.
What is endogenous and exogenous selective attention?
Endogenous attention is the ability to voluntarily direct attention depending on goals, expectations, and/or knowledge. It’s the conscious directing of attention to a particular aspect of the environment.
Exogenous attention is where numerous stimuli arise from events, conditions, or the environment to attract attention automatically. It is where stimuli arise from the environment and attract our attention involuntarily.
What is the inhibition of return? How does it describe the relationship between endogenous and exogenous attention?
Exogenous cueing effects start earlier (than endogenous) and are short-lived. They begin at 75 milliseconds after the cue and last only a few hundred milliseconds. At longer intervals (400-800 milliseconds) the effect of the target validity is reversed - subjects respond more slowly to targets in the cued location. → IOR
May promote exploration of new unattended places/objects in the environment by slowing the return of attention to recently attended ones.
What brain regions are involved in attention?
The frontal Eye Field is involved in attentional control and eye movements.
The Frontoparietal lobe is involved in the directing of attention as well as controlling eye movements.
The superior Colliculus also plays a crucial role in directing eye movement
The lateral intraparietal area is important in the creation of salience maps.
The ocular system is suggested to be the cause of IOR. The activity in the ocular system affect moto responses reaction times through inhibition of Return
What is the difference between salience maps and priority maps? Where is this created?
LIP - The creation of Salience Maps
- Neglect syndrome
→Salience Maps - A map of exogenous cues, inciting competition based on 'salience'; A map of contrasting features in order to direct attention. → Priority Maps - A priority map is a map showing locations where attention should be directed based on stimulus salience and cognitive input. In other words, a priority map is a salience map plus top-down effects. Hence, Attentional Direction based on both Salience and Individual Decision.
How do deformations in the retina affect vision?
Retina is non-uniform
: Colour vision is only possible in the fovea. The cone photoreceptors in the retina responsible for colour vision.
Anything you’re not pointing your eyes at, light isn’t directly on the cones (perceived in B and W) - brain computes and fills in the gaps - this image is created by the rods
Another deformation: neurons that pass info from eye to brain don’t just present pure image but they convey contrast: contrast in nervus opticus
What is Bayes rule, and how does it apply to explaining priors?
Our brain is constantly re-creating the outside image based on the ambiguous info from the retina - what we see is made up by ourselves based on crude info from the eye - in order to make up for this we use priors
The rule tells you how to update your existing beliefs in the light of new evidence
What do the frontoparietal attention networks look like in top-down and bottom-up attention?
In bottom-up attention, information about a conspicuous object is passed from visual areas in the occipital lobe to LIP are where a salience map is constructed. Early attention signals are also seen in the prefrontal cortex and the frontal eye fields that interact with the LIP. Signal sent from LIP and FEF may direct the eyes and enhance visual processing in the occipital visual cortex.
In top-down attention, frontal lobe areas show attentional modulation at the earliest times and signals sent to other structures influence eye movements and perception.
What is the importance of a salience map?
Salience map model is a hypothesis that explains how visual features grab our attention (bottom-up attention)
First stage is that the model consists of maps of individual features that locate areas of higher feature contrast.
Via neural interactions within a map, a form of competition may suppress responses associated with lower feature contrast
High contrast areas of the feature maps feed into a salience map that locates high contrast areas regardless of specific features.
This competition between locations of high contrast → winning location → moving of attention.
IOR is used to prevent attention from “getting stuck” by preventing successive attentional loci from being the same.
What is associated with lesions in the LIP?
neglect syndrome
What is associated with dysfunction of the Parietal Lobe
Stroke in parietal lobe → attention-deficit → unilateral neglect → ignoring a specific side of the environment. Typically means you’re ignoring everything on the left side.
Lateralization - asymmetry in how attention is divided between L and R sides of the brain.
The right parietal cortex pays attention to the whole visual world. The left parietal cortex pays attention to only the left side of the world.
What is Williams Beuren Syndrome?
Genetic syndrome of Ch. 7. There is a small part of the ch that isn’t stable, susceptible to damage.
You have genes that code for proteins if mutated you can still develop - although short life expectancy.
Mutations in CYLN2 and GTF2i → neuropsychological profile → lack spatial attention
Loss of connection between the different elements of objects (house and bicycles)
