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what role does attention play in visual search

by Markus Block Published 1 year ago Updated 7 months ago

In turn, attention modulates visual search by selecting and limiting the information available at various levels of processing. Focusing on the intersection of attention and search provides a relatively structured window into the wide world of attentional phenomena.

Attention acts by enhancing the response to the attended stimulus and by restricting the range and number of units responding to the distractors. Both processes improve performance by increasing the discriminability of the attended signal.Aug 30, 2001

Full Answer

What is attention and visual search?

This special feature issue is devoted to attention and visual search. Attention is a central topic in psychology and visual search is both a versatile paradigm for the study of visual attention and a topic of study in itself. Visual search depends on sensory, perceptual, and cognitive processes.

What is the role of attention in search performance?

Data from physiology and psychophysics show that performance in a search task is largely determined by the discriminability of the target from the distractors. Attention acts by enhancing the response to the attended stimulus and by restricting the range and number of units responding to the distractors.

What is the most definitive work on attention mechanisms?

The most definitive psychophysical work that distinguishes between different attention mechanisms has come from recent experiments by Dosher and Lu Lu and Dosher 1998, Lu and Dosher 1999, Dosher and Lu 2000a, Dosher and Lu 2000b, Lu et al. 2000.

What do behavioral studies of visual search measure?

The vast majority of the behavioral studies of visual search measure the response time to report the presence or absence of the target. The key here is recognizing that the speed of response time is related to the difficulty of discrimination.


What is the role of attention in visual search?

Visual search is a type of perceptual task requiring attention that typically involves an active scan of the visual environment for a particular object or feature (the target) among other objects or features (the distractors). Visual search can take place with or without eye movements.

How does attention relate to visual perception?

By focusing on a certain location or aspect of the visual scene, attention allows us to selectively process information, prioritizing some aspects of information while ignoring others. Attention lies at the crossroads between perception and cognition.

What factors influence visual search?

It is guided to the most promising items and locations by five factors discussed here: bottom-up salience, top-down feature guidance, scene structure and meaning, the pre- vious history of search over timescales ranging from milliseconds to years, and the relative value of the targets and distractors.

What role does attention play in perception?

Not only does our attentional system allow us to focus on something specific in our environment while tuning out irrelevant details, but it also affects our perception of the stimuli surrounding us.

Does attention enhance perception?

These findings reveal that attention enhances the appearance of perceptual organization, a midlevel vision process, altering the way we perceive our visual environment. Our world does not appear to us in terms of bits and pieces; instead, we see things as unified wholes, such as objects and surfaces.

Is attention necessary for perception?

1 Although the leading consensus holds that attention is necessary but not sufficient for conscious perception, it is possible that attentional processes are part of the minimal set of mechanisms that are jointly sufficient.

Is visual search selective attention?

Visual search is a key paradigm in attention research that has proved to be a test bed for competing theories of selective attention. The starting point for most current theories of visual search has been Treisman's “feature integration theory” of visual attention (e.g., Treisman & Gelade, 1980. and Gelade, G. 1980.

What are the factors that affect attention?

What are the determining factors of attention?Intensity: the more intense a stimulus is (strength of stimulus) the more likely you are to give attention resources to it.Size: the bigger a stimulus is the more attention resources it captures.Movement: moving stimuli capture more attention that ones that remain static.More items...

What factor do you think Determine your attention?

Internal (Subjective) factors: The subjective factors which influence attention are interests, motive, mind set and our attitudes & moods. It is believed that interest is the mother of attention, as we pay attention or focus on those objects about which we have interest.

Why is focus and attention important?

Focussed attention leads to quicker and more directed completion of a task, thereby leading to a sense of success, thus improving wellbeing. The person will enjoy the task more, and will take ownership of the process they undertook to complete it.

What is the concept of attention?

It is the taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought. Focalization, concentration, of consciousness are of its essence. It implies withdrawal from some things in order to deal effectively with others.

What is the process of attention?

Broadly, the attention process can be described as selective concentration on salient environmental features while ignoring other aspects. From: Psychology and Geriatrics, 2015.

What are the types of visual attention?

There are three main types of visual attention: (1) spatial attention, which can be either overt, when an observer moves his/her eyes to a relevant location and the focus of attention coincides with the movement of the eyes, or covert, when attention is deployed to relevant locations without accompanying eye movements; ...

How does selective attention direct our perceptions?

How does selective attention direct our perceptions? We selectively participate and process a very limited part of the incoming information, which has too many obstacles and transfers our attention from one thing to another. When we carefully focus on a task, we often show careless blindness to other events.

Why is it important to understand development of visual attention in infants?

Infants have substantial limitations in their abilities to comprehend information, verbally communicate, and use their hands, arms, and legs to manipulate objects, move about the world, and explore. For them, visual attention (or looking) is a critical means for learning about the world.

How does attention operate?

What is Attention? Attention is the ability to choose and concentrate on relevant stimuli. Attention is the cognitive process that makes it possible to position ourselves towards relevant stimuli and consequently respond to it. This cognitive ability is very important and is an essential function in our daily lives.

Author information

Smith-Kettlewell Eye Research Institute, 2232 Webster St., 94115, San Francisco, CA

Additional information

This work was supported by Grant IF32 EY06155 from the NEI and Grant 83–0320 from the AFOSR.

Why is attention important in visual search?

Attention can also improve visual search. Even if the memo is not distinguishable by color, it is easier to find if attention is drawn to its location. For instance, the telephone might ring and as I turn to answer it, I might discover the memo sitting next to the phone.

How does visual attention affect search?

A framework based on signal detection theory shows how visual attention influences tasks that require searching for a target among distractors. Data from physiology and psychophysics show that performance in a search task is largely determined by the discriminability of the target from the distractors. Attention acts by enhancing the response to the attended stimulus and by restricting the range and number of units responding to the distractors. Both processes improve performance by increasing the discriminability of the attended signal.

What is the second stage of conjunction search?

The attentive, serial second stage has been invoked especially to explain conjunction search. In conjunction search, the target differs from the distractors by a unique combination of features; the target cannot be characterized by a single unique attribute. An example of a conjunction search task is a target that is a bright vertical line among distractors that are dark vertical lines and bright tilted lines. Neither brightness nor orientation alone defines the target uniquely. Treisman and Gelade (1980) suggest that the second limited-capacity stage, which depends on attention, integrates the features that define the target. Attention is therefore thought to be indispensable for successful conjunction search performance.

How does signal detection theory work?

More recently, a few researchers have proposed that signal detection theory (SDT), the standard model used to predict human psychophysical thresholds, can be applied to visual search. SDT has successfully predicted detection and discrimination in a search paradigm, without additional assumptions about limited-capacity. Instead of a two-stage process with a parallel, unlimited-capacity front end, followed by a limited-capacity attention stage, they have proposed a parallel stage followed by a simple decision rule. SDT describes search accuracy with many fewer assumptions than are required to predict response time to find the target. So in the interests of a simpler exposition, I will first present SDT as it applies to search accuracy, and then present SDT in the context of response time. According to SDT, the elements in a visual search display are internally represented as independent, noisy random variables. Consider for instance an easy search task such as searching for a line tilted 45° clockwise among vertical lines as shown in Figure 1A. SDT assumes that the observer is monitoring the output of a matched filter—a detector matched to the properties of the signal to be detected or discriminated. In the case of the 45° target, the matched filter is a detector at the location of the target with a preferred orientation of 45°, and a receptive field size that matches the target size; repeated presentations of the same stimulus generate responses that vary about a mean value. The probability of a given response strength is idealized as a bell-shaped Gaussian distribution that is centered on this mean response value. The variability about the mean is due to noise within the visual system, at the level of the detector. A similar response profile is generated physiologically when a neuron is presented with multiple trials of the same stimulus Bradley et al. 1987, Newsome et al. 1989. The physiological equivalent of the SDT framework is a neuron that is well suited to detecting the target, i.e., one that has a receptive field that includes the target location and a preferred orientation that matches the target tilt of 45°. The neural response to multiple trials is a distribution of spike counts with a mean spike rate and some variability about the mean. Thus, the red distribution in Figure 1B represents both the abstract SDT concept of a noisy internal representation generated by the tilted target, as well as the probability of different spike counts in response to the tilted target. SDT assumes that the vertical distractors generate a smaller response from the filters selective to the tilted target. Thus, the mean response level to a distractor is smaller than the mean response to the target (blue versus red distribution in Figure 1B ). In the physiological domain, neurons tuned to the tilted target will have a smaller response to the vertical distractors, which also can be reasonably represented by the blue distribution in Figure 1B. For simplicity, I assume that the variances of the two distributions (red and blue) are the same.

Why is display duration brief?

Display duration is typically brief to avoid eye movement contamination. The stimuli are placed at about equal eccentricity, and are presented without masks; stimuli are not too closely spaced so that they do not violate the independence assumption of signal detection theory Palmer 1994, Verghese and Stone 1995, Eckstein et al. 2000.

What is the first stage of search performance?

The first stage of processing is thought to occur before the influence of attention and is called preattentive.

Is the target and distractor the same?

So far in the discussion it has been implicitly assumed that the variance of the target and distractor distributions is the same. In reality, this might not be the case. The variance of the two distributions can be different leading to quite different search outcomes depending on whether the elements with the larger intrinsic variance are assigned to the target or distractor. When the target has the larger variance, search is easier than when the distractor is drawn from the large-variance distribution. This explains why search performance sometimes changes dramatically if the identities of the target and distractor are reversed. Treisman and coworkers Treisman and Souther 1985, Treisman and Gormican 1988 have called this class of findings “search asymmetries.” These findings are also predicted by signal detection theory. Palmer et al. (2000) have shown that accuracy in finding the target decreases as a function of sigma ratio, which is the ratio of the standard deviations of the distractor to the target distribution. This trend accounts for the change in performance when the target and distractor identities are interchanged. For example, it is much easier to find a tilted line among vertical lines than to find a vertical line among tilted lines. Sutter et al. (2000) showed that this asymmetry was due to the higher intrinsic variability of the tilted line.


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