6. Visual Attention Flashcards
What are the 3 ways that selectivity of attention can be demonstrated?
- Inattentional blindness
- Change blindness e.g. Door study
- Attentional blink
Describe a study that investigated inattentional blindness.
Study have different images of a cross with different lengths of vertical and horizontal arms. Subject was asked to indicate which arm was longer. In between the images, a random shape woulud be presented with the cross. Subject was then asked to recognise which shape was presented earlier. Most subjects will miss the shape because they were too concentrated at looking for the longer arm of the cross.
Describe a study that demonstrated attentional blink.
Rapid serial visual presentation. Different images with a letter or number were presented 100msec each. It was shown that it takes at least 500msec for subjects to perceive targets. Subjects therefore cannot perceive the targets that were presented within the 500mec time frame.
What are endogenous and exogenous attention?
Exogenous attention is pre-attentive/ bottom-down. It is something that appears without expectations. These attention tasks are often effortless to the subjects. Such as spotting a red balloon among a sea of blue balloons.;
Endogenous attention is attentive/ top-down. It requires effort and takes time for subjects to sort through a clutter of information in search for the target. E.g. Finding a specific face in a crowd.
What are the two types of endogenous attention? What are the differences between them?
Spatial attention & Feature-based attention. Spatial attention helps to confine processing to a particular location or object. E.g. focussing on the road while driving; Feature-based attention helps to process all objects sharing a common feature. E.g. all red cars in a carpark.
What is Treisman’s Feature Integration Theory?
Treisman’s theory suggests that we have overt and covert attention. Covert attention acts as an attentional spotlight, which acts on areas early along the visual pathway and aid in early selection of where we should focus our visual field. Covert attention refers tto the surroundings to our fixation target; Overt attention is our actual fixation point, the target that we are looking at.
What are the differences between parallel search and serial search?
Parallel search is pre-attentive. It is conducted when looking for a unique feature that pops out, such as colour or orientation that is different from most of the surroundings; Serial search combines different features, such as both colour and orientation. Therefore serial search requires time and attention.
How do the reaction times differ with serial search and parallel search when the number of items to be searched through increases?
For parallel search, increasing number of items doesn’t change reaction time. For serial search, increasing number of items increases reaction time linearly. There are many factors that can affect the slope in serial search, including the magnitude of difference between the target and its surroundings, crowdiness of the scene etc.
There are many factors that guide attention:
* … is a stimulus-driven guidance. This is when the target consist of features that …;
* …, is a user-driven guidance. This is when the attention is …;
* Scene guidance is when … guides attention to areas that …;
* … of some items or features
* … of prior search
There are many factors that guide attention:
* Bottom-up is a stimulus-driven guidance. This is when the target consist of features that attact from attention than the others;
* Top-down, is a user-driven guidance. This is when the attention is directed to objects with known features of desired targets;
* Scene guidance is when specific attributes of the scene guides attention to areas that is more likely to contain the targets;
* Perceived value of some items or features
* History of prior search
Where in the brain is speculated to be the most likely source of attentional spotlight?
Posterior parietal cortex
In a macaque study that investigated the ..., electrodes are placed into the ... of the posterior parietal cortex. A Priority/ Saliency Map was constructed that shows how attention was distributed. It was found that attention was spent the most at objects that are most similar to the target, and also to targets that are highly salient, meaning that they are attractive to the observer.
In a macaque study that investigated the attentional spotlight, electrodes are placed into the lateral intraparietal sulcus of the posterior parietal cortex. A Priority/ Saliency Map was constructed that shows how attention was distributed. It was found that attention was spent the most at objects that are most similar to the target, and also to targets that are highly salient, meaning that they are attractive to the observer.
Name the 4 visual areas of macaque related to attention.
- V1
- V4, TE, TEO
- LIP
- V5/ MT
For humans, ... was used to investigate visual attention in the human ` …. It was found that attentional spotlight was …. As the visual stimulus moves further away from the fovea, the activity in the brain …. There is …` by sectors of visual stimuli.
For humans, functional MRI was used to investigate visual attention in the human primary visual cortex. It was found that attentional spotlight was swept across sectors of a visual scene. As the visual stimulus moves further away from the fovea, the activity in the brain shifts gradually. There is retinotopic activation in V1 by sectors of visual stimuli.
How do damages to the dorsal and ventral pathway affect activity respectively?
Dorsal pathway is the where/ action pathway. Damages will lead to impaired goal-directed action; Ventral pathway is the what/ perception pathway. Damages will lead to agnosia, therefore the person can no longer perceive certain objects/ features.
Magicians can manipulate audience’s attention in order to create the illusion or tricks. They may distract audience by showing ... objects. This is achieved with a ... , where distracting objects are of .... They also include ..., which can cause a ... movement of the audience’s eyes. Magicians may also ask subjects to perform tasks that uses ..., or uses their own gaze to .... There can also be ..., where one captures more attention. Separation in time of trick and the magical effects is called the .... ... can also be used to distract attention from the actual trick.
Magicians can manipulate audience’s attention in order to create the illusion or tricks. They may distract audience by showing salient objects. This is achieved with a bottom-up/ sensory approach, where distracting objects are of higher contrast &/or bigger. They also include fast, curvilinear movements, which can cause a smooth pursuit movement of the audience’s eyes. Magicians may also ask subjects to perform tasks that uses top-down processes, or uses their own gaze to misdirect attention. There can also be split attention between two concurrent tasks, where one captures more attention. Separation in time of trick and the magical effects is called the time misdirection. Comedy and laughter can also be used to distract attention from the actual trick.
