Searching the visual scene - A2

Question 1

What did original ideas about how we search the visual scene suggest?

Answer 1

searches that rely on more than one element of the target (e.g. red crosses) are less efficient than ones that rely on one element (e.g. red)

Question 2

What factors are usually varied in visual search tasks?

Answer 2

• number of distractors
• presence or absence of targets (positive or negative)

Question 3

What are feature searches and conjunction searches?

Answer 3

• feature = target is distinct from distractors by one feature
• conjunction = target is distinct by a combination of features

Question 4

What are the findings for visual search tasks for feature searches?

Answer 4

• positive trials = size of the array doesn’t affect RT
• negative trials = size of array does affect RT (more to search to check it isn’t there)

Question 5

What are the findings for visual search tasks for conjunction searches?

Answer 5

• the size of the array increasing always increases RT
• this increase in RT is greater for negative trials

Question 6

When looking at visual search task results, what does m represent in the equation?

Answer 6

the increase in RT for every new item added to the array

Question 7

What are the 2 processing stages in Feature integration Theory? What are some characteristics of them?

Answer 7

• feature detection - fast, parallel, automatic and efficient - single features pop out
• feature integration - gluing all the features together (attentional focus is the glue) - slow, inefficient search

Question 8

What did Wolfe find with regards to the predictions made by feature integration theory?

Answer 8

there is no real pattern in the results between feature and conjunction searches

Question 9

What does Wolfe’s model of guided search suggest?

Answer 9

• there is a top-down part that constrains how you search and a bottom-up part that interact to create a more efficient search

Question 10

What is an example that supports Wolfe’s model of guided search?

Answer 10

When looking for a red item of specific orientation it is easier to find it when some of the shapes are green than them all being red as the top-down process can make you ignore all the green items, reducing the search

Question 11

What things drive bottom-up search? (2)

Answer 11

• salience (target is more or less different to distractors)
• attributes (elements that capture attention)

Question 12

What drives top-down search? (2)

Answer 12

• scene properties
• values

Question 13

What does attentional engagement theory suggest?

Answer 13

the efficiency of the search is based on aspects of the task
- target/non-target similarity and non-target/non-target similarity

Question 14

How does target/non-target similarity affect search?

Answer 14

more similar = target less likely to pop out so search is less efficient

Question 15

How does non-target/non-target similarity affect search? What implications does this have?

Answer 15

• if they are heterogeneous (all different) then search is less efficient, even though they still only differ by one dimension from the target
• doesn’t fit with FIT as that suggests that one dimension different = should always pop out

Question 16

What are guiding attributes according to Wolfe (2004)?

Answer 16

Ways in which an item can differ from the distractors, and these attributes differ in the amounts to which they affect efficiency of the search

Question 17

How does context affect searching for an object?

Answer 17

It constrains search to areas that are likely to have that object (e.g. a horse will be on the ground not in the sky)
top-down, guided search

Question 18

What are the 2 pathways in Wolfe’s model?

Answer 18

• selective pathway - recognition of stimuli’s elements
• non-selective pathway - basic semantic information from the scene (gist)

Question 19

What did Anderson et al (2011) find when they altered the reward value associated with coloured circles that served as distractors in a search task?

Answer 19

RT was higher the higher the value of the distractor

Question 20

What other individual factors affect distraction? (2)

Answer 20

• low working memory scores = high distraction
• higher impulsivity scores = high distraction