Cognition and Visual Search & Detection

Question 1

What is search and detection?

Answer 1

• Searching the visual field for item of interest “search”
• Determining if the item is the target (“detection”)

Question 2

What is feature search?

Answer 2

You look for a feature; you are looking for something that shouldn’t be there. Defined as a parallel process in which the target and the distractors are maximally different, differentiated by a single property such as colour, shape, orientation or size.

Fast (300ms); Parallel (<10ms/item); No attention needed. (also known as a disjunctive or an efficient search) as introduced by Treisman and Gelade (1980)

Question 3

What are two types of visual search?

Answer 3

Feature search and conjunction search.

Question 4

What is conjunction search?

Answer 4

Conjunction search (inefficient search) also described by Treisman and Gelade (1980) [3] occurs when the target and the distractors share similarities in more than one single visual property such as size, colour, orientation and shape.

Slower that featuer search, you are making realtive comparisons; more effort is needed; defined by something that has multiple variables, such as size and color. Attention is needed. Looking for more detail. Slow (>500ms); Serial (>10ms/item)

Question 5

What are the types of eye movement through the visual field?

Answer 5

1. Serial Search Model
2. Structured Search

Question 6

In visual searchs, what is the serial search model?

Answer 6

Items inspected serially to determine target/non-target. Search patterns affected by organization of space (e.g., left right/top down if organized; more random and less exhaustive if no pattern).

For targets that are not readily visible, the increase in p(detect) diminishes with time. If the task becomes less interesting or boring, interest decreases.

The more organized, the less time it takes to find something. The more unorganized, the longer it takes. Searching unorganized environments is exhausting

Question 7

What are four aspects of saccadic eye movements?

Answer 7

1. length of movement depends on time to initiate, move, dwell
2. destination can be biased, top down (where you expect to find something) or drawn to salient (stand out) information – flashing light
3. dwell time affected by content (e.g., short vs. long words) and ease of information extraction – stimulus quality
4. useful field of view (detail, or more salient features which can be found through non-foveal vision)

Question 8

What are structured searches of saccadic eye movements?

Answer 8

Examine items in set in systematic manner. E.g, menus (structured set).

Directing attention (salient cue) - you can draw attention in one direction. Exmaple: if the stop sign or light is not in the expected place, it might not get noticed because it isn’t where poeple expect.

Question 9

What are depth cues?

Answer 9

Information in the environment that allow us to perceive depth. These sources of information are commonly called depth or distance cues.

Question 10

What influences the outcome of a visual search?

Answer 10

1. Expectancy: where a target might be use to structure display so know where to start the visual search
2. Conspicuity: Conspicuity of stimuli leads to its detection (“pops out”) of field – search is effectively parallel, or all at once rather than serial

Question 11

What happens when a traget is found during a visual search?

Answer 11

Once possible target has been detected through search, must decide if it is in fact a target

Question 12

What is a parrallel search?

Answer 12

All items are considered at once (as in conspicuity search).

Question 13

What are target properties included in parallel searches?

Answer 13

1. Discriminability from background elements. (color, size, brightness, motion, etc.
2. Simplicity: can the target be defined only one dimension and not several.
3. Automaticity: a target that is highly familiar. ( one’s own name)