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29 Cards in this Set
- Front
- Back
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Give 4 examples of a real-world implication of visual search research (i.e. situations in which visual-search is important) |
In baggage security scan monitors In mammography searches for tumours In the military - camouflage In the supermarket when browsing products |
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In what proportion of mammography scans will a tumour actually be visible and in need of detection? |
0.3% of the time |
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Describe Neisser's (1964) lab-based study of visual search with letter strings. |
1. Participants were tasked with searching for Ks in a series of 6-letter strings arranged in a column 2. The task was repeated, looking for strings without Qs 3. Participants had to search for a Z in letter strings of angular or curved letters
Average time and time as a function of how far down the list the string was, was recorded
Results: - Z was found twice as quickly in curved strings as in angular strings - absence of Qs took longer to find than presence of Ks
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What were the two types of visual search tested by Treisman and Gelade, (1980) |
1. conjunction search 2. single feature search |
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What different results did Treisman and Gelade note when people engaged in single-feature vs. conjunction search tasks?
What did they conclude from this? |
Single: no increase in RT with increasing number of distractors
Conjunction: linear increase in RT with increasing number of distractors
Single-feature search involves parallel processing and targets stand out in a pop-out effect whereas conjunction feature searches are serial searches that take time and effort. |
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What are the feature maps and the master map of the Feature Integration Theory? |
Feature maps: topographical representations of the different levels of a particular feature in the visual display.
Master map: the conglomerate of all the feature maps that binds them all together |
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What is the attentional spotlight according to Treisman and Gelade? |
In conjunction searches we can effortfully move our attention across the master map representation of a scene in order to look for particular feature conjunctions |
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Treisman and Schmidt (1982) proposed three ways in which features can be bound together to represent objects. What were they? |
1. Attentional spotlight on master map 2. Stored knowledge and rules-of-thumb 3. Random illusory conjunctions |
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Describe the experiment conducted by Treisman and Schmidt (1982) that highlighted the existence of illusory conjunction effects. |
1. Stimuli was a brief display of two black digits flanking three letters of different colours 2. Task was to report the black digits and then, as a secondary priority, to report whatever they could remember about the letters in the middle. 3. People tended to be able to report the letters and the colours correctly, but matched the letters with the wrong colours.
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What has the study of patient RM told us about the neurological underpinnings of illusory conjunctions? |
1. RM has bilateral parietal-occipital lesions 2. Task: presented with two objects and told to name the shape and colour of the first one that he saw. 3. Results: 13% illusory conjunctions after 10s More successful with successive than simultaneous presentations 4. Conclusions: perhaps the master map of location is in the parietal-occipital region |
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What three strands of the FIT do we have empirical support for? |
1. The apparent distinction between serial and parallel processing
2. Illusory conjunctions occurring under conditions of attentional overload
3. Neurophysiological plausibility of conjunction processing areas (TMS to the parietal region induces impaired performance in conjunction searches.) |
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What is the 'Pip and Pop Effect' experiment conducted by Van der Burg et al. (2008)?
What is it evidence of? |
1. Display contains many red and green lines arranged at various orientations and flashing in different rhythms. 2. The task is to locate, for example, a red horizontal target. 3. The task is made easier when a sound is played that beeps in time with the target's flashing rhythm.
Conjunctions of sound and visual pattern seem to aid, rather than slow, search. Conjunctions of more than 2 factors = easier to spot. |
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Describe Fujisaki et al.'s (2008) windmill study. |
1. A number of spinning windmills are displayed and the participant must determine which one is spinning exactly in time with a 'woo-ing' sound being played through headphones. 2. Task difficulty was moderated by increasing the number of windmills - RT was proportional to the number of distractors. |
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What evidence is there against the idea that attributing a sound to something in synchrony with it becomes increasingly difficult with more distractors? |
Speech perception in a crowd |
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Give 2 examples of studies that found a particular conjunction of features that helped, rather than hindered, visual search. |
Nakayama and Silverman (1986) Conjunction: colour and depth
McLeod, Crisp and Driver (1988) Conjunction: form (X/O) and movement
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Describe the study conducted by Kim and Cave (1995) investigating whether spatial attention is required even for single-feature target searches. |
Task: speeded response to feature or conjunction target, either with or without a location probe following the target display. Results: in both types of search, spatial probes significantly increased accuracy |
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Describe Mack and Rock's (1998) experiment testing whether attention is required for individual feature searches.
What is a key design flaw that might affect the reliability of the results? |
Display: a horizontal white line crossing a vertical white line with a number of green dots in each of the four quadrants Fake task: determine which line is longer Real task: do you notice the pink circle and if so can you recall the colour and location of it.
Results: 44% fail to see it at all 50% fail to see either colour or position only 6% accurately report both features
Due to the surprise nature of the task, each participant can only sit through one trial of the experiment. |
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Describe how Duncan and Humphreys (1989) varied target and distractor similarities to highlight a key aspect of visual search. |
Varied: Homogeneity of distractor set Similarity between distractors and target
Found: Reaction times were greatest when the distractor set was heterogeneous and the target was not dissimilar from the distractors
Concluded: there is a continuum of search efficiency |
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When interpreting search slopes what do the following indicate:
1. flat search function 2. positive slopes |
1. parallel processing 2. EITHER serial processing OR noisy parallel processing |
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Describe the task used by Wolfe, Cave and Franzel (1989) to support their Guided Search Model suggesting that information from feature maps can guide attentional focus on the master map. |
1. A display of a 3x3 grid contained a target stimulus (of a particular orientation, size and colour) and various distractors characterised by 1 shared features with the target.
Compared to searches done with only two defining features, this triple conjunction search task was easier (participants took less time).
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Describe a task that highlights possible memory confounds in supposed 'illusory conjunction' evidence. |
Virzi and Egeth (1984) Display: blank 8 digits blank two digits flanking three coloured words blank
Task: judge whether the edge numbers had changed in the two displays and then recall the words and the colours they were printed in
Results: Illusory conjunctions often found when one of the words was the name of a colour |
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What are four flaws of the FIT? |
1. Pop-out conjunctions have been found 2. Attention is required for feature search in some cases 3. Serial and parallel processing are not clearly distinct 4. Illusory conjunctions may reflect a memory problem rather than a perceptual one. |
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What is the 'stare in the crowd' effect and what does it suggest? |
In a large display of 'eye pictures' looking in different directions, any pair looking directly at us immediately pops out.
Targets that have more salience from an evolutionary perspective are automatically given more attention as this was relevant to threat avoidance in the past. |
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What are illusory figures? Why might some things pop-out whilst others don't? Give two examples of such pop-out items. |
E.g. we see squares where actually only four corners are perceived - the lines connecting them are illusions
If something is a surprise or is unusual, it might pop-out from more familiar stimuli, e.g. 'dead elephants' and bumps among 'un-bumps' |
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How can synaesthesia inform us about pop-out targets in visual search? |
Synaesthetes may find visual search easier if they experience particular colours for particular letters as this would give the target a unique feature that would 'pop out' |
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What other sensory domains, besides visual search, might utilise similar principles? |
Taste |
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How do real-world visual search experiences differ from lab-based research? |
1. Frequency of target presentation (50% vs. 0.3% for mammograms) 2. Identification of exactly what the target will look like |
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What did Wolfe, Horowitz and Kenner (2005) find when analysing how target prevalence affects target identification success rates? |
At standard lab levels of around 50%, participants rarely missed an item.
When targets were presented just 1% of the time there was a large failure of detection rate even with only 3 distractors in the display |
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How might we check that luggage security operators are paying attention and increase target identification rates?
Give a potential limitation of this approach. |
Insert false targets from time to time
Operators often improve in their detection of false targets without this affecting their detection success of real targets. |
