This article may be too technical for most readers to understand.(August 2019) |
Attentional blink (AB) is a phenomenon that reflects temporal limitations in the ability to deploy visual attention. When people must identify two visual stimuli in quick succession, accuracy for the second stimulus is poor if it occurs within 200 to 500 ms of the first. [1]
The AB is typically measured by using rapid serial visual presentation (RSVP) tasks, where participants often fail to detect a second salient target if it is presented within the blink. [2] The AB has also been observed using two backward-masked targets [3] and auditory stimuli. [4] [5] The term attentional blink was first used in 1992, [2] although the phenomenon was probably known before. [6] [7]
The precise adaptive significance behind the attentional blink is unknown, but it is thought to be a product of a two-stage visual processing system attempting to allocate episodic context to targets. In this two-stage system, all stimuli are processed to some extent by an initial parallel stage, and only salient ones are selected for in-depth processing, in order to make optimum use of limited resources at a late serial stage. [8]
One curious aspect of the attentional blink is that it usually includes "lag-1 sparing". Targets presented very close together in time with no intervening distractors (at "lag 1" or consecutively in the RSVP stream) are not affected by the attentional blink, even though items presented at greater lags with intervening distractors are significantly impaired. This sparing can be spread over multiple targets, as long as no non-target items occur between them in the stream. [9] Lag-1 sparing can be explained by theories in which attentional engagement with the stream is suppressed upon detection of a non-target stimulus. [10] [11]
According to the LC-NE hypothesis, [12] when a salient, or meaningful stimulus is presented, neurons in the locus coeruleus release norepinephrine, a neurotransmitter that benefits the detection of the stimulus. The effect of this release lasts for 100 ms after the salient stimulus is presented and benefits the second target when presented immediately after the first one, accounting for lag 1 sparing. Eventually the neurons in the locus coeruleus enter a refractory period, due to the auto-inhibitory effect of norepinephrine. According to the hypothesis, targets presented during this refractory period cannot trigger a release of norepinephrine, resulting in the attentional blink. The episodic distinctiveness hypothesis of the ST2 model [13] suggests that the attentional blink reflects a limitation of the visual system attempting to allocate unique episodic contexts to the ephemeral target stimuli presented in RSVP.
The attentional blink is sometimes used to measure differences in attention between particular populations or experimental conditions [14] [15]
One factor which influences the AB is emotional information. When the second target (T2) in an RSVP stream is an emotionally relevant stimulus it is more likely to be perceived during the period during which the AB typically occurs. The AB is not only modulated by emotional relevance of (T2) but also by the emotional relevance of (T1). When (T1) is emotionally relevant the AB is lengthened and when (T2) is emotionally relevant, the AB is reduced. This suggests that emotion can mediate attention. [16] [17]
Raymond et al. (1992) [18] suggest that the attentional blink is produced by perceptual uncertainty amongst the target (T1) and following target (T2). They suggest that this confusion happens at some point in the target identification processes. When confusion is eliminated, attentional blink isn't observed. The researchers also suggested that one way to eliminate confusion is to have items that cannot be named.
Shapiro et al. (1994) [19] suggest that an interference model may better explain the attentional blink effects than the inhibition model. In this model, the attentional blink is thought to take place because of an out of place item which is selected out of the series because of the interference within the items in the series. Shapiro proposes that the amount of interference increases or decreases with the length of the series.
Giesbrecht and Di Lollo (1998) [20] suggest that the attentional blink over target 2 results when the person is busy processing target 1. It is suggested that anything increasing the difficulty of processing of the first target will result in a greater attentional blink.
Duncan et al. (1996) [21] suggest that the target 1 takes over parts of our attentional capacity, leading to a deficit of processing or recognizing target 2 when presented immediately after target 1. This theory suggests that the time for which target 2 continues to occupy attentional capacity is related directly to the difficulty of processing target 1.
Chun & Potter (1995) [22] suggest that quickly processing a series of items requires two back to back stages. The first stage is the initial rapid-detection. Here, the possible targets are noticed. The second stage is the capacity-limited in which items are taken in order to report later. Stage 2 occurs after the acknowledgement of targets in Stage 1. Here, stage 2 must finishing processing target 1, until then, target 2 will not be recognized in stage 2. If there is a situation where the second target comes in the first stage, the highway to stage two is delayed. Attentional blinking occurs when target 2 is in stage 1 but target 1 is still in stage 2 so target 2 can not get to stage 2. The attentional blink mirror a restriction in the process of combining information from an unstable representation to a stable representation (Johnson & Proctor, 2004). [23]
Attention or focus, is the concentration of awareness on some phenomenon to the exclusion of other stimuli. It is the selective concentration on discrete information, either subjectively or objectively. William James (1890) wrote that "Attention 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." Attention has also been described as the allocation of limited cognitive processing resources. Attention is manifested by an attentional bottleneck, in terms of the amount of data the brain can process each second; for example, in human vision, less than 1% of the visual input data stream of 1MByte/sec can enter the bottleneck, leading to inattentional blindness.
In the study of vision, visual short-term memory (VSTM) is one of three broad memory systems including iconic memory and long-term memory. VSTM is a type of short-term memory, but one limited to information within the visual domain.
Iconic memory is the visual sensory memory register pertaining to the visual domain and a fast-decaying store of visual information. It is a component of the visual memory system which also includes visual short-term memory (VSTM) and long-term memory (LTM). Iconic memory is described as a very brief, pre-categorical, high capacity memory store. It contributes to VSTM by providing a coherent representation of our entire visual perception for a very brief period of time. Iconic memory assists in accounting for phenomena such as change blindness and continuity of experience during saccades. Iconic memory is no longer thought of as a single entity but instead, is composed of at least two distinctive components. Classic experiments including Sperling's partial report paradigm as well as modern techniques continue to provide insight into the nature of this SM store.
Feature integration theory is a theory of attention developed in 1980 by Anne Treisman and Garry Gelade that suggests that when perceiving a stimulus, features are "registered early, automatically, and in parallel, while objects are identified separately" and at a later stage in processing. The theory has been one of the most influential psychological models of human visual attention.
Repetition blindness (RB) is a phenomenon observed in rapid serial visual presentation. People are sometimes poor at recognizing when things happen twice. Repetition blindness is the failure to recognize a second happening of a visual display. The two displays are shown sequentially, possibly with other stimuli displays in between. Each display is only shortly shown, usually for about 150 milliseconds. If stimuli are shown in between, RB can occur in a time interval up to 600 milliseconds. Without other stimuli displayed in between the two repeated stimuli, RB only lasts about 250 milliseconds. Repetition blindness tasks usually are words in lists and in sentences. They are called phonologically similar items. There are also pictures, and words that include pictures. An example of this is a picture of the sun and the word sun. The most popular task used to examine repetition blindness is to show words one after another on a screen fast in which participants must recall the words that they saw. This task is known as the rapid serial visual presentation (RSVP). Repetition blindness is present if missing the second word creates an inaccurate sentence. An example of this is "When she spilled the ink there was ink all over.” An RSVP sequence participants will recall seeing "When she spilled the ink there was all over." However, they are missing the second occurrence of "ink". This finding supports that people are "blind" for the second occurrence of a repetitive item in an RSVP series. For example, a subject's chances of correctly reporting both appearances of the word "cat" in the RSVP stream "dog mouse cat elephant cat snake" are lower than their chances of reporting the third and fifth words in the stream "dog mouse cat elephant pig snake".
Inhibition of return (IOR) refers to an orientation mechanism that briefly enhances the speed and accuracy with which an object is detected after the object is attended, but then impairs detection speed and accuracy. IOR is usually measured with a cue-response paradigm, in which a person presses a button when they detect a target stimulus following the presentation of a cue that indicates the location in which the target will appear. The cue can be exogenous, or endogenous. Inhibition of return results from oculomotor activation, regardless of whether it was produced by exogenous signals or endogenously. Although IOR occurs for both visual and auditory stimuli, IOR is greater for visual stimuli, and is studied more often than auditory stimuli.
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 among other objects or features. Visual search can take place with or without eye movements. The ability to consciously locate an object or target amongst a complex array of stimuli has been extensively studied over the past 40 years. Practical examples of using visual search can be seen in everyday life, such as when one is picking out a product on a supermarket shelf, when animals are searching for food among piles of leaves, when trying to find a friend in a large crowd of people, or simply when playing visual search games such as Where's Wally?
The metaphor "stream of consciousness" suggests how thoughts seem to flow through the conscious mind. Research studies have shown that humans only experience one mental event at a time as a fast-moving mind-stream. The term was coined by Alexander Bain in 1855 in the first edition of The Senses and the Intellect, when he wrote, "The concurrence of Sensations in one common stream of consciousness enables those of different senses to be associated as readily as the sensations of the same sense". But it is commonly credited to William James, who used it in 1890 in his The Principles of Psychology. The full range of thoughts—that one can be aware of—can form the content of this "stream".
Priming is a concept in psychology to describe how exposure to one stimulus may influence a response to a subsequent stimulus, without conscious guidance or intention. The priming effect is the positive or negative effect of a rapidly presented stimulus on the processing of a second stimulus that appears shortly after. Generally speaking, the generation of priming effect depends on the existence of some positive or negative relationship between priming and target stimuli. For example, the word nurse might be recognized more quickly following the word doctor than following the word bread. Priming can be perceptual, associative, repetitive, positive, negative, affective, semantic, or conceptual. Priming effects involve word recognition, semantic processing, attention, unconscious processing, and many other issues, and are related to differences in various writing systems. How quickly this effect occurs is contested; some researchers claim that priming effects are almost instantaneous.
Emotion can have a powerful effect on humans and animals. Numerous studies have shown that the most vivid autobiographical memories tend to be of emotional events, which are likely to be recalled more often and with more clarity and detail than neutral events.
Illusory conjunctions are psychological effects in which participants combine features of two objects into one object. There are visual illusory conjunctions, auditory illusory conjunctions, and illusory conjunctions produced by combinations of visual and tactile stimuli. Visual illusory conjunctions are thought to occur due to a lack of visual spatial attention, which depends on fixation and the amount of time allotted to focus on an object. With a short span of time to interpret an object, blending of different aspects within a region of the visual field – like shapes and colors – can occasionally be skewed, which results in visual illusory conjunctions. For example, in a study designed by Anne Treisman and Schmidt, participants were required to view a visual presentation of numbers and shapes in different colors. Some shapes were larger than others but all shapes and numbers were evenly spaced and shown for just 200 ms. When the participants were asked to recall the shapes they reported answers such as a small green triangle instead of a small green circle. If the space between the objects is smaller, illusory conjunctions occur more often.
Perceptual learning is learning better perception skills such as differentiating two musical tones from one another or categorizations of spatial and temporal patterns relevant to real-world expertise. Examples of this may include reading, seeing relations among chess pieces, and knowing whether or not an X-ray image shows a tumor.
N2pc refers to an ERP component linked to selective attention. The N2pc appears over visual cortex contralateral to the location in space to which subjects are attending; if subjects pay attention to the left side of the visual field, the N2pc appears in the right hemisphere of the brain, and vice versa. This characteristic makes it a useful tool for directly measuring the general direction of a person's attention with fine-grained temporal resolution.
Broadbent's filter model is an early selection theory of attention.
Object-based attention refers to the relationship between an ‘object’ representation and a person’s visually stimulated, selective attention, as opposed to a relationship involving either a spatial or a feature representation; although these types of selective attention are not necessarily mutually exclusive. Research into object-based attention suggests that attention improves the quality of the sensory representation of a selected object, and results in the enhanced processing of that object’s features.
Crossmodal attention refers to the distribution of attention to different senses. Attention is the cognitive process of selectively emphasizing and ignoring sensory stimuli. According to the crossmodal attention perspective, attention often occurs simultaneously through multiple sensory modalities. These modalities process information from the different sensory fields, such as: visual, auditory, spatial, and tactile. While each of these is designed to process a specific type of sensory information, there is considerable overlap between them which has led researchers to question whether attention is modality-specific or the result of shared "cross-modal" resources. Cross-modal attention is considered to be the overlap between modalities that can both enhance and limit attentional processing. The most common example given of crossmodal attention is the Cocktail Party Effect, which is when a person is able to focus and attend to one important stimulus instead of other less important stimuli. This phenomenon allows deeper levels of processing to occur for one stimulus while others are then ignored.
Emotion perception refers to the capacities and abilities of recognizing and identifying emotions in others, in addition to biological and physiological processes involved. Emotions are typically viewed as having three components: subjective experience, physical changes, and cognitive appraisal; emotion perception is the ability to make accurate decisions about another's subjective experience by interpreting their physical changes through sensory systems responsible for converting these observed changes into mental representations. The ability to perceive emotion is believed to be both innate and subject to environmental influence and is also a critical component in social interactions. How emotion is experienced and interpreted depends on how it is perceived. Likewise, how emotion is perceived is dependent on past experiences and interpretations. Emotion can be accurately perceived in humans. Emotions can be perceived visually, audibly, through smell and also through bodily sensations and this process is believed to be different from the perception of non-emotional material.
In cognitive psychology, intertrial priming is an accumulation of the priming effect over multiple trials, where "priming" is the effect of the exposure to one stimulus on subsequently presented stimuli. Intertrial priming occurs when a target feature is repeated from one trial to the next, and typically results in speeded response times to the target. A target is the stimulus participants are required to search for. For example, intertrial priming occurs when the task is to respond to either a red or a green target, and the response time to a red target is faster if the preceding trial also has a red target.
Visual spatial attention is a form of visual attention that involves directing attention to a location in space. Similar to its temporal counterpart visual temporal attention, these attention modules have been widely implemented in video analytics in computer vision to provide enhanced performance and human interpretable explanation of deep learning models.
Perceptual load theory is a psychological theory of attention. It was presented by Nilli Lavie in the mid-nineties as a potential resolution to the early/late selection debate.