L10 - Attention Pt 2

Question 1

What is visual search?

Answer 1

• Something unconscious: trying to match things you are seeing to what you want e.g finding car in car park = seen in games
• Without exo cues = laborious to search = must be deliberate (endogenous)
• We do not detect the whole image at once

Question 2

What is the fundamental difference between the two types of search?

Answer 2

• Some are easy: pop-out effect = uniqueness of item causes exogenous attention
• Others are harder as there are lots of colours that stand out = making it endogenous attention = need to check each area to find the red circle = called FEATURE search
• Other is conjuncture search

Question 3

What is the difference between feature and conjunction search?

Answer 3

Feature =
- Do exp to detect odd-one-out = time taken to detect object is the same regardless of how many objects are on the screen
- Finding things that are defined by a single feature like colour is easy/effortless
- Not much difference with different orientation and colour = pop-out searches
Conjunction =
- Do not pop-out = conjunction of colour and orientations and you must know both of these to find the target
- More items on the screen = longer it takes to find item
- Takes 2x as long for absent trials than present trials as you must go through each individually (when present = you only look until you find it = less items looked at)

Question 4

What is the Feature Integration Theory?

Answer 4

• Each feature in the image is registered in feature-maps e.g blue-things, left-ward moving things etc. and is done without any attention
• To join these feature maps requires attention = attention acts like the glue
• You can do a feature search without attention as no gluing is required, but for conjunction, you have to move attention from location to location and gluing things together.
• Should be cases where we get it wrong = when we are distracted = illusory conjunctions

Question 5

What is a feature of integration theory? (study)

Answer 5

• Ppts have to search for a lollipop in a field of circles, and then a circle in a field of lollipops
• When you look for the lollipop was there = did not matter the number of distractors, RT was same for absent and present
• When looking for the circle = number of distractors increased the RT = absent was much higher RT than present
• If we had a feature map for circles and for lines: we can identify the line because we do not need the glue (attention), when looking for circle: we see circles and lines in our feature maps so we have to use attention to distinguish

Question 6

What is the FIT problems?

Answer 6

• Things that would not normally be regarded as features also show pop-out
• e.g low level things like motion, colour and depth can pop-out but when turned or demonstrated in another way, it became a conjunctive task
• Also claims that higher-order things such as facial expressions also pop-out
• STUDY: time to find angry face in a crowd of happy faces is faster and is the same for four or eight faces
• Time to find happy faces in crowd of angry increases from four to eight faces
• Unique threat to angry faces so focus on them

Question 7

What are other FIT problems? (conjunction)

Answer 7

• Things that should not pop-out do: conjunction was depth and colour
• Found that it is very easy regardless of distractors
• Conjunction of depth and colour pops-out and conjunction of movement and colour pops-out

Question 8

What is a guided search by Wolfe?

Answer 8

• You can use some knowledge to restrict your search to these items
• We have feature maps but they feed in centrally to a salience map: just identifies salience of items: no info about colour/motion etc.
• Model uses the idea of a salience map = both high and low-level factors govern the activation of this map
• Allows for a difference between an item’s salience and its perceptual representation
• Reproduces a lot of results in human experiences

Question 9

What are visual search with eye movements?

Answer 9

• Normal visual search uses eye-movements (result due to attention and not movement of eye)
• When stimuli is big, you can find the target without movement of eyes, but when small, you must move eyes to find target
• Can use covert vs overt (eyes are moving) movements show that things that happen in both types of exps: feature: eye moves immediately to target, conjunction shows eye-movements fluctuating
• Strong relationship between no. of saccades (eye movement) and time taken to search
• Allows us to explore how we search in similarity: move eyes to things most similar to target AND closeness: move to object that is close to where you are looking
• Mechanisms that move our attention also move our eyes

Question 10

What is our attentional network?

Answer 10

• Neuropsychological expts have identified at least 3 areas involved in attention
• PET and fMRI imaging of the brain has confirmed role of parietal cortex in attention shifting in control subjects
• Posterior Parietal lobe: disengages attention
• Superior Colliculus: move our attention
• Pulvinar: enhances attention

Question 11

What is the superior colliculus?

Answer 11

• Less acknowledged: useful in reptiles as they do not have V1
• Direct connection from LGN
• Important in control of eye-movements and attention
• Has direct connection to extrastriate cortex - hand-eye movements
• Has multi-sensory input = important for reflexes

Question 12

What was a study of the Superior Colliculus (SC)?

Answer 12

• Stimulation of the SC produces eye-movements
• Put electrodes onto SC and found where eyes move to (has motor map that can be stimulated)
• Found one cell and worked out what space the eyes/attention moved to, stimulated the cell a little
• Pre-cueing paradigm conducted
• Instead of cue stimulated the SC with a sub-threshold pulse that did not move the eyes
• Targets appearing at cued location were detected better than other areas
• Close link between attention and eye movements

Question 13

What is neglect?

Answer 13

• More prevalent when right parietal cortex is damaged than the left but both produce neglect and on opposite sides = most patients have left neglect = when drawing they will leave out left side
• People with neglect cannot even imagine their left side e.g when asked to imagine a famous landmark will only describe things on the right BUT when they are told to walk back in the opposite direction, they mention everything on the right (they previously could not imagine)

Question 14

What is the relationship between neglect and visual search? (3 studies)

Answer 14

• To identify neglect, you can draw a line on a piece of paper and ask them to find the midpoint
• Can draw lots of Ls and Ts and ask them to cross out all Ts (also seen by their eye-movements)
• Ask them to point out which side fingers are being wiggled

Question 15

What was research about the right parietal lesion?

Answer 15

• Ppts had a right parietal lesion
• Create a letter out of other little letters and ask them to report the big letter = more autistic traits would be distracted by the little letters and would report wrong
• Those with neglect can identify the whole letter, then asked to cross out all the little letters making up the word
• They can identify the whole big letter and see it is made up of all the little letters, but only cross half of them out as they cannot bring their attention to the left hand-side
• Then asked to draw a H from memory with dots with eyes shut, then asked to open eyes and cross them out - and couldn’t
• Then gave them two objects and asked to cross out individual letters, BUT crossed out right hand side of each object (even the one on the left) = suggesting neglect is not just spatial but object based = can detect object but neglect the left side