Week 3 Visual Search

Question 1

What is the difference between serial and parallel processing?

Answer 1

Serial processing = one process commences only after the first process is completed, indicades narrow attentional breadth

Parallel processing = multiple processes occur at the same time, indicades broad attentional breadth

Question 2

What is the difference between dimension and feature in visual search?

Answer 2

A dimension is a range of variation analysed by a separate perceptual system, ie. orientation or colour

A feature is a particular value of a dimension, eg. red as feature of a colour, vertical is a feature of orientation

Question 3

What does the Feature Integration Theory suggest about how features and separate dimensions form coherent images?

Answer 3

1. Single features are processed parallel to each other
2. These separate features are encoded onto distinct feature maps of the visual scene
3. Focused attention is the glue that acts as a serial process that ‘binds’ together separate features and identifies the stimulus

Question 4

What do seach arrays use to measure visual search attention?

Answer 4

1. A search array - a series of stimuli in a scene where participants have to engage in exercise of detection (is it there), localisation (where is it?), identification task (is it blue or green?)
2. It is surrounded by other stimuli often called distractors or non-targets
3. IV = The set size is the number of objects in total in a search array
4. DV = is often reaction time / accuracy

Question 5

What can set size tell us about visual search?

Answer 5

Set size is used to infer whether the objects are being processed serially or in parallel depending on if RT changes with increasing the set size.

If the RT does change when set size is increased, it indicates that all the objects are being processed at the same time ( parallel search).

If RTs get longer and longer as more objects are added, this indicates that the objects are being processed separately in a serial search, where attention is being implied to each individual object.

Question 6

What type of visual search task is predicted to use feature/parallel search?

Answer 6

According to Feature Integration Theory, is predicted that when you are only that looking for only one feature (colour or shape) - you use parallel processing because it’s easier to process things at the same time when you’re only looking for one feature.

Question 7

What type of visual search task is predicted to use conjunction /serial search?

Answer 7

FIT predicts that looking for a stimulus in a search array with multiple features, you use serial processing, because it’s harder to process multiple things at the same time when having to scan and distinguish between multiple features you’re looking for

Question 8

What type of visual search, serial or parallel, IS affected by increasing set size?

Answer 8

Serial/conjunction search - it’s harder to process multiple things at the same time when having to scan and distinguish between multiple features you’re looking for.

Question 9

Why do target-absent trials often take longer to complete than target-present trials?

Answer 9

• because you have to scan through every stimulus in the search array and then determine whether your stimulus is absent

Question 10

What does the Attentional-Engagement Theory predict about visual search efficiency?

Answer 10

When distractors are highly similar, and/or there is a large difference between the target and the distractors, visual search for a target is highly efficient, as the distractors become categorised as something similar and processing becomes parallel even if the distractors have different features, eg. vary in colour or shape

Question 11

What is the problems with a emotion attention study using snakes/spiders over flowers/mushrooms?

Answer 11

1. The array of neutral objects and emotive objects is too varied, ie. different sizes and colours of the different stimulus categories would affect reaction time and how visual search is conducted
2. There is an assumption of what is fear-relevant, ie. assumption that snakes and spiders are more emotionally fearful than mushrooms (neutral condition)
3. While evolutionally driven objects may influence our attention, other more modern (less evolutionally established) such as a car, gun, etc. are equally emotionally provocative stimuli.

Question 12

How does serial and parallel processing relate to attentional breadth?

Answer 12

1. Parallel search is able to categorise distractors and process everything all at once, it would allow one to use a broader attentional breadth,
2. Serial visual search would have to use a narrower attentional breadth to focus on local features and process them separately

Question 13

Why is visual search studies conducted for?

Answer 13

To determine how humans are likely to miss a target in low prevalence contexts compared to high prevalence contexts even as set size increases.

Question 14

What is the attentional bottleneck as a delay in attentional processes?

Answer 14

AB is the tendency to struggle to attend to multiple attentional tasks quickly after another, it is a failure to encode a second stimulus closely before the first stimulus

Question 15

What is the attentional blink paradigm and how is it used?

Answer 15

1. It measures visual search for targets across time, rather than across space = temporal attentional limitation
2. Requires people to attend to 2 targets in a rapid, serial visual presentation (RSVP), where stimuli are presented quickly 100ms and in the same location, eg. find the 2 letters amongst distractors of numbers
3. Findings show that once the first target is found, a deficit in finding the second target for several hundred ms

Question 16

How are lags used to manipulate efficiency of AB?

Answer 16

A lag is temporal offset between targets of 100ms each, ie. “lag 3” means target 2 is the third item after target 1, in between are distractors.

Lag 3 would indicate a 300 ms stimulus onset asynchrony (SOA) between the two targets

Question 17

What is conditional accuracy in AB paradigms?

Answer 17

An accuracy dependent variable where AB paradigm can only measure effects of SOA/lag if participants identify both targets - T2 | T1)
but T1 identification often has ‘ceiling effects’ in accuracy

Question 18

Is attentional blink a perceptual, sensory or an attentional limitation?

Answer 18

When researchers abolish the need to find T1 first, the AB effect for T2 disappears, indicating that the percept of the target is easy to detect. This implies that AB is not a perceptual limitation.

Rather, the requirement to identity T1 before T2 causes the attentional deficit in T2, as the encoding of T1 overrides the encoding of T2 as its being processed into more conscious and durable representation in the STM. Therefore, it appears to be a limitation in attentional processing to identify 2 targets

Question 19

What does the two-stage model of attention help explain about why AB occurs?

Answer 19

Stage 1 - detects stimulus, holds multiple items, temporary, fragile (iconic memory)
Stage 2 - encodes into conscious and durable representation (STM)

1. Encoding into stage 2 into the STM is slow and creates delays in attention (bottleneck)
2. In AB, when T2 occurs in too quick succession (lag 2-4) with T1, T2 is overwritten and lost in stage 1/iconic memory, because T1 is still being processed across the stages 1-2 into STM

Question 20

What are the general findings of the attentional blink paradigm?

Answer 20

In AB, when T2 occurs in too quick succession (lag 2-4) with T1, T2 is overwritten and lost in stage 1/iconic memory, because T1 is still being processed across the stages 1-2 into STM

However, when T2 occurs directly after T1 (lag 1), accuracy is high, most likely because both targets are being processed in parallel into STM. At longer lags (lag 4-8), accuracy is also high, mostly likely because T1 has been effectively encoded into STM and T2 can be effectively processed.

Question 21

What is the emotional AB paradigm?

Answer 21

This paradigm includes 2 targets but one is emotionally salient, either being target 1, or target 2, which produce opposite effects in attention

Question 22

What happens when T1 is more emotionally salient in the AB paradigm?

Answer 22

With the emotional salient stimulus as T1, it is thought to cause an even bigger AB delay for then identifying T2

Question 23

What happens when T2 is more emotionally salient in the AB paradigm?

Answer 23

When T2 is more emotionally salient, T2 is found to reduce AB delay, especially for people with anxiety

Question 24

What is the EIB paradigm (Emotional induced blindness paradigm)?

Answer 24

1. Only one target needs to be identified
2. An emotionally salient distractor image is shown before T1, which is shown to produce attentional bottleneck in finding T1, because of its high visual salience, even though its not task-relevant.

Question 25

What is the IV, task requirements and findings of the EIB?

Answer 25

IV: Lag and emotive vs. neutral events

Task: You are looking to see whether the target has been rotated 90˚ left or 90˚ right

Findings: People have lower accuracy on target trials with emotive distractors shown beforehand, for both positive and negative salient distractors.

Question 26

How is emotion-induced blindness measured from the EIB paradigm?

Answer 26

EIB magnitude is measured as the difference in accuracy in T1 target identification between the emotive and neutral distractor

Question 27

How does the visuospatial field/attentional breadth play a role in EIB effect?

Answer 27

When you have targets in a rapid, serial visual presentation series of images playing out on two screens:

1. EIB blindness was produced ONLY when the emotionally-salient distractor was in the same stream as T1, not on the adjacent screen.
2. Implies that EIB effect is dependent on the distractor being in the same spatial location as the target

Question 28

How does viligine avoidance help explain why people could avoid EIB with two screens?

Answer 28

Vigilance avoidance is moving spatial attention away from the stimulus that is perceived as distressing/negative valence

Vigilance avoidance typically occurs in highly anxious individuals leading to higher amounts of emotionally-induced blindness in a normal EIB paradigm

However, in the two screens, participants had less EIB when they had a (still goal relevant) space to move their eyes towards (opposite stream condition).