Showing papers on "Attentional blink published in 2004"

Modulation of long-range neural synchrony reflects temporal limitations of visual attention in humans.

Abstract: Because of attentional limitations, the human visual system can process for awareness and response only a fraction of the input received. Lesion and functional imaging studies have identified frontal, temporal, and parietal areas as playing a major role in the attentional control of visual processing, but very little is known about how these areas interact to form a dynamic attentional network. We hypothesized that the network communicates by means of neural phase synchronization, and we used magnetoencephalography to study transient long-range interarea phase coupling in a well studied attentionally taxing dual-target task (attentional blink). Our results reveal that communication within the fronto-parieto-temporal attentional network proceeds via transient long-range phase synchronization in the beta band. Changes in synchronization reflect changes in the attentional demands of the task and are directly related to behavioral performance. Thus, we show how attentional limitations arise from the way in which the subsystems of the attentional network interact.

Is Consciousness a Gradual Phenomenon? Evidence for an All-or-None Bifurcation During the Attentional Blink

Abstract: Several theories of the neural correlates of consciousness assume that there is a continuum of perception, associated with a gradual change in the intensity of brain activation. But some models, considering reverberation of neural activity as necessary for conscious perception, predict a sharp nonlinear transition between unconscious and conscious processing. We asked participants to evaluate the visibility of target words on a continuous scale during the attentional blink, which is known to impede explicit reports. Participants used this continuous scale in an all-or-none fashion: Targets presented during the blink were either identified as well as targets presented outside the blink period or not detected at all. We suggest that a stochastic nonlinear bifurcation in neural activity underlies the all-or-none perception observed during the attentional blink.

Identification Facilitation for Emotionally Arousing Verbs During the Attentional Blink.

Abstract: The present study aimed to examine affective modulation of the "attentional blink" effect during rapid serial visual presentation (RSVP). Pleasant, neutral, and unpleasant written verbs were used as a 2nd target (T2) in an 8.6-Hz RSVP paradigm. Pronounced effects of 1st target (T1)-T2 stimulus onset asynchrony (SOA) were found, showing reduced report accuracy for 232- and 464-ms SOAs. Affectively arousing (pleasant and unpleasant) T2s were associated with enhanced accuracy compared with neutral T2s specifically during short (232 ms) SOAs. In contrast, pleasant and unpleasant T2s rated low in terms of emotional arousal did not show this enhancement. These results suggest that affectively arousing information is selected preferentially from a temporal stream, facilitating processes such as working memory consolidation and action.

Rapid serial visual distraction: Task-irrelevant items can produce an attentional blink

Abstract: When two sequential targets (T1 and T2) are presented within about 600 msec, perception of the second target is impaired. This attentional blink (AB) has been studied by means of two paradigms: rapid serial visual presentation (RSVP), in which targets are embedded in a stream of central distractors, and the two-target paradigm, in which targets are presented eccentrically without distractors. We examined the role of distractors in the AB, using a modified two-target paradigm with a central stream of task-irrelevant distractors. In six experiments, the RSVP stream of distractors substantially impaired identification of both T1 and T2, but only when the distractors shared common characteristics with the targets. Without such commonalities, the distractors had no effect on performance. This points to the subjects’ attentional control setting as an important factor in the AB deficit and suggests a conceptual link between the AB and a form of nonspatial contingent capture attributable to distractor processing.

Paying Attention to Meaning

Abstract: Several paradigms show that responses to one event compromise responses to a second event for around 500 ms. Such effects are generally attributed to attentional capacity limitations associated with processing information in the first event. In a task in which targets could be distinguished only by their meaning, we varied the semantic relationship between distractors and targets following at different lags. Semantic relatedness alone produced a classic attentional blink. We conclude by discussing how attention theory might best accommodate these new effects.

Revisiting within-modality and cross-modality attentional blinks: Effects of target—distractor similarity

Abstract: When two masked targets (T1 and T2) require attention and are presented within half a second of each other, the report accuracy for T2 is reduced, relative to when the two targets are presented farther apart in time. This effect is known as the attentional blink (AB). Potter, Chun, Banks, and Muckenhoupt (1998) argued that all AB-like effects observed when at least one of the targets was presented outside of the visual modality did not represent true instances of the AB, but instead were artifacts of task-set switching. However, in the Potter et al. experiments the presence or absence of task-set switching opportunities was confounded with the T2 task, as well as the alphanumeric class of T2 with respect to the distractors. In the present experiment, we examine the influence of T1 alphanumeric class, T2 alphanumeric class, and switching operations in a fully crossed design that unconfounds these factors. In contrast to the conclusions of Potter et al., the present results suggest that the T2 alphanumeric class can account for the pattern of ABs observed across conditions, without necessarily implicating a separate switch cost. The implications for theoretical models of the AB and the debate over the validity of cross-modal ABs are discussed.

On the saliency of negative stimuli: Evidence from attentional blink1

Abstract: When people are asked to detect two targets from a rapid serial visual presentation (RSVP) stream, impairment of recognition of the second target (T2) can be observed if the T2 is presented several hundred milliseconds later than the first target (T1). This phenomenon is known as attentional blink, and is considered to reflect some temporal characteristic of the attentional process. The aim of the present study was to use the attentional blink paradigm to examine whether the affective meaning of the stimuli could affect the magnitude of attentional blink. In Experiment 1, the valence of the T2 (neutral, positive, and negative) was manipulated. Significant T2 detection deficit was observed with neutral and positive T2 but not with negative T2. Experiment 2 demonstrated that non-significant attentional blink in negative T2 in Experiment 1 could be attributed to the negative affective meaning of T2. Results are discussed in terms of the high saliency of negative information.

A psychophysical measure of attention deficit in children with attention-deficit/hyperactivity disorder.

Abstract: The authors explored the temporal mechanism of attention deficit in children with attention-deficit/ hyperactivity disorder (ADHD). In rapid serial visual presentation tasks in which two targets (T 1 and T2) were presented in close temporal proximity among distractors, participants tried to identify T 1 and detect T2 in one (dual-task) experiment and only to detect T2 in a second control (single-task) experiment. The sensitivity of T2 detection was analyzed using signal detection theory. The attentional blink—the impairment in T2 detection following the identification of T 1—was increased in magnitude and protracted in the patients. Moreover, some ADHD children appeared to have a blink largely normal in magnitude but temporally displaced toward a later time. The authors hypothesize that a slower closing of the attention gate may mediate this specific attention impairment in ADHD children.

Task- and location-switching effects on visual attention.

Abstract: In two experiments, we examined the effects of task and location switching on the accuracy of reporting target characters in an attentional blink (AB) paradigm. Single-character streams were presented at a rate of 100 msec per character in Experiment 1, and successive pairs of characters on either side of fixation were presented in Experiment 2. On each trial, two targets appeared that were either white letters or black digits embedded in a stream of black letter distractors, and they were separated by between zero and five items in the stream (lags 1-6). Experiment 1 showed that report of the first target was least accurate if it immediately preceded the second target and if the two targets were either both letters or both digits (task repetition cost). Report of the second target was least accurate if one or two distractors intervened between the two targets (the U-shapedAB lag effect) and if one target was a letter and the other a digit (task switch cost). Experiment 2 added location uncertainty as a factor and showed similar effects as Experiment 1, with one exception. Lag 1 sparing (the preserved accuracy in reporting the second of two targets if the second immediately follows the first) was completely eliminated when the task required attention switching across locations. Two-way additive effects were found between task switching and location switching in the AB paradigm. These results suggests separate loci for their attentional effects. It is likely that the AB deficit is due mainly to central memory limitations, whereas location-switching costs occur at early visual levels. Task-switching costs occur at an intermediate visual level, since the present task switch involved encoding differences without changes in stimulus-response mapping rules (i.e., the task was character identification for both letters and digits).

Object file continuity predicts attentional blink magnitude.

Abstract: When asked to identify targets embedded within a rapid consecutive stream of visual stimuli, observers are less able to identify the second target (T2) when it is presented within half a second of the first (T1); this deficit has been termed the attentional blink (AB). Rapid serial visual presentation methodology was used to investigate the relationship between the AB and object files (episodic representations implicated in object identification and perceptual constancy). An inverse linear relationship was found between the degree of object file continuity and AB magnitude. An important locus of object file continuity was the intervening stream items between T1 and T2. The results are discussed in terms of the heuristic of the object file to preserve limited attentional capacity.

Transcranial magnetic stimulation to right parietal cortex modifies the attentional blink

Abstract: The 'attentional blink' (AB) reflects a limitation in the ability to identify multiple items in a stream of rapidly presented information. Repetitive transcranial magnetic stimulation (rTMS), applied to a site over the right posterior parietal cortex, reduced the magnitude of the AB to visual stimuli, whilst no effect of rTMS was found when stimulation took place at a control site. The data confirm that the posterior parietal cortex may play a critical role in temporal as well as spatial aspects of visual attention.

Eyes, brains, and autos.

Abstract: Vision disorders pose a driving safety risk and commonly arise at the level of the eye in cataract, glaucoma, macular degeneration, and diabetic retinopathy and at the level of the brain in advancing age, stroke, and Alzheimer disease and related conditions. These disorders can increase driver safety errors because of reduced visual acuity, contrast sensitivity,andvisualfields.Agingandbrainlesions,especially,canalsoreducetheusefulfieldofviewin drivers with normal visual fields; increase the attentional blink and change blindness; impair perceptionofstructureanddepthfromvisualmotioncuesandmotionparallax;decreaseperceptionofheading from optical flow and detection of impending collisions; and increase the chance of getting lost. Better tools are needed for detecting and alerting visually impaired drivers who are at greatest risk for a crash. These drivers can be assessed with a state-administered road test, instrumented vehicles, and driving simulators. Emerging safety interventions include optical and electronic visual aids for visuallyimpaireddrivers,coupledwithnewvehicledesigns,onboardwarningdevices,andreflectiveclothing that highlights the motion of pedestrians.

Blink and shrink: the effect of the attentional blink on spatial processing.

Abstract: The detection or discrimination of the second of 2 targets in a rapid serial visual presentation (RSVP) task is often temporarily impaired—a phenomenon termed the attentional blink. This study demonstrated that the attentional blink also affects localization performance. Spatial cues pointed out the possible target positions in a subsequent visual search display. When cues were presented inside an attentional blink (as induced by an RSVP task), the observers’ capacity to use them was reduced. This effect was not due to attention being highly focused, to general task switching costs, or to complete unawareness of the cues. Instead, the blink induced a systematic localization bias toward the fovea, reflecting what appears to be spatial compression. Vision is set within space and time. Visual objects occupy limited spatial regions as well as limited time periods as they continuously move in and out of people’s visual fields (as birds and cars usually do), as they gradually emerge from behind other, occluding objects when people themselves move around, or as they abruptly come into existence (such as blinking traffic lights). Vision is also highly selective. People are unaware of, or cannot remember having seen, the details of most objects in a visual scene even if they are directly looking at them (Mack & Rock, 1998; O’Regan, Deubel, Clark, & Rensink, 2000; Simons & Levin, 1997). Instead, certain visual events are prioritized whereas others are ignored. The study of visual selective attention looks at the determinants and level of this selection process. The bulk of the research has focused on the spatial component of visual selection. In visual search, for instance, observers search for visual objects relevant to their task (targets), located in a visual field filled with a variable number of irrelevant objects (distractors). Efficient selection of the target may be quite difficult, for instance, when the target shares its features with the surrounding distractors or when attention is drawn to the wrong location by a more salient object. Under other circumstances, selection can be quite effortless, for example, when the target carries a salient feature distinguishing it from the distractors or when observers are cued toward its location (Duncan & Humphreys, 1989; Pylyshyn et al., 1994; Theeuwes, 1991; Theeuwes, Kramer, & Atchley, 1999; Treisman & Gelade, 1980; Wright, 1994). More recently, researchers have started to explore the temporal dynamics of visual selection. In the rapid serial visual presentation (RSVP) task, observers again look for a target among a number of distractors. Contrary to the visual search task, where target and

Possible sources of perceptual errors in P300-based speller paradigm

Abstract: Some perceptual phenomena can interfere with character identification in Farwell and Donchin's P300-based speller paradigm: attentional blink, repetition blindness and other effects caused by attentional limits. In the paper we discuss these and provide empirical evidence for one class of perceptual errors.

Mask-dependent attentional cuing effects in visual signal detection: the psychometric function for contrast.

Abstract: A spatial-cuing paradigm was used to test the hypothesis of Carrasco, Penpeci-Talgar, and Eckstein (2000) that the mask-dependent cuing effects found in visual signal detection by Smith (2000a) were caused by submaximal activation of the transient-orienting system. Mask-dependent cuing was found with a range of stimulus contrasts with pure peripheral cues and with the mixed central-peripheral cues of Smith (2000a), contrary to the predictions of the submaximal activation hypothesis. The use of a pedestal detection task to control spatial uncertainty showed that the cuing effect was due to signal enhancement. A model of mask-dependent cuing is described, which assumes that attention affects the rate of information accumulation from the display and that masks limit the visual persistence of the stimulus. The model correctly predicts differential mask dependencies in sensitivity for detection and discrimination and the associated patterns of response times.

Is Consciousness a Gradual Phenomenon? for an All-or-None Bifurcation During the

Abstract: Several theories of the neural correlates of consciousness assume that there is a continuum of per- ception, associated with a gradual change in the intensity of brain activation. But some models, considering rever- beration of neural activity as necessary for conscious perception, predict a sharp nonlinear transition between unconscious and conscious processing. We asked partici- pants to evaluate the visibility of target words on a con- tinuous scale during the attentional blink, which is known to impede explicit reports. Participants used this contin- uous scale in an all-or-none fashion: Targets presented during the blink were either identified as well as targets presented outside the blink period or not detected at all. We suggest that a stochastic nonlinear bifurcation in neural activity underlies the all-or-none perception ob- served during the attentional blink. Whether there can be a strict dissociation between conscious and unconscious processing is a debated issue. Some imaging studies of visual perception show a gradual increase in the cortical activity evoked by a stimulus as participants report

Attentional blink reflex modulation in a continuous performance task is modality specific

Abstract: Four experiments investigated the attentional modulation of acoustic blinks during continuous spatial tracking tasks. Experiment 1 found blink magnitude inhibition in a visual tracking task. Experiment 2 replicated this finding and also found blink latency slowing. Experiment 3 varied the difficulty of the task and found larger blink inhibition in the easy condition. Blink latency slowing did not differ and was significant at both difficulty levels. Experiment 4 employed less difficult visual and acoustic tracking tasks at two levels of task load. Blink magnitude inhibition during the visual and facilitation during the acoustic task was significant during high load in both modality groups. Blink latency was slowed in all visual task conditions and shortened in the difficult acoustic task. These results indicate that attentional blink modulation in a continuous spatial tracking task is modality specific.

Repetition blindness: out of sight or out of mind?

Abstract: Does repetition blindness represent a failure of perception or of memory? In Experiment 1, participants viewed rapid serial visual presentation (RSVP) sentences. When critical words (C1 and C2) were orthographically similar, C2 was frequently omitted from serial report; however, repetition priming for C2 on a postsentence lexical decision task was equivalent whether or not C1 was similar to C2. In Experiment 2, participants monitored RSVP sentences for a predetermined target. Participants frequently failed to detect the target when it was preceded by an orthographically similar word. In Experiment 3, the authors investigated the role of the attentional blink in this effect. These experiments suggest that repetition blindness is a failure of conscious perception, consistent with predictions of the token-individuation hypothesis.

The attentional blink is susceptible to concurrent perceptual processing demands.

Abstract: In a rapid serial visual presentation stream processing of a first target (T1) impairs detection or identification of a second target (T2) that appears within 500 ms after T1. This effect character...

Capturing attention when attention blinks.

Abstract: Four experiments addressed the question of whether attention may be captured when the visual system is in the midst of an attentional blink (AB). Participants identified 2 target letters embedded among distractor letters in a rapid serial visual presentation sequence. In some trials, a square frame was inserted between the targets; as the only geometric object in the sequence, it constituted a singleton. Capture effects obtained when the AB was most severe and when it was over were compared. There were 3 main results. First, capture occurred even when the AB was crippling, suggesting that a singleton exogenously engaged attention even when processing of a previous target was continuing apace. Second, when the singleton contained the key target feature, capture effects were clearly manifest. Third, even when the singleton did not possess the key target feature, it still succeeded in capturing attention, although the effects were both feeble and fleeting.