Eye movements blink the attentional blink

When presented with a sequence of visual stimuli in rapid succession, participants often fail to detect a second salient target, a phenomenon referred as the attentional blink (AB; Raymond, Shapiro, & Arnell, 1992; Shapiro, Raymond, & Arnell, 1997). On the basis of a vast corpus of experiments, several cognitive theories suggest that the blink results from a discrete structuring of attention, sampling information from temporal episodes during which several items can access encoding process (Wyble, Bowman, & Nieuwenstein, 2009; Wyble, Potter, Bowman, & Nieuwenstein, 2011). The objective of this work is to explore the AB when multiple items are presented at the fovea during ocular movements. The authors reasoned that each fixation may cohesively form an episode and hence expected that the blink may vanish within a single fixation. In turn, they expected saccades to accentuate episodic borders and hence shorten the regime of interference when 2 targets are presented fovealy in successive fixations. Evidence is provided in favor of this hypothesis, showing that the blink vanishes when both targets are presented in the core of a single fixation (far from the saccadic boundaries) and that it recovers more rapidly in successive fixations. These studies support current views that episodes should have an effect on the AB and provide evidence that eye movements play an important role in the formation of episodes.     

The attentional blink and lag 1 sparing are nonspatial

The attentional blink (AB) refers to the finding that the perception of the second of two targets (T2) is impaired when presented in close temporal proximity to the first target (T1). An exception to this deficit occurs when T2 immediately follows T1, an effect referred to as lag 1 sparing. So far, it has been unclear whether the AB is location specific or nonspatial in nature. Most demonstrations of an AB across different locations have shown an absence of lag 1 sparing, due to accompanying spatial switch costs. This means that the AB pattern itself may be explained through such switch costs. In this study, to minimize spatial switch costs, attention was made to move continuously across multiple locations by aid of a cue. An AB across different locations was found, including lag 1 sparing. We conclude that the AB and lag 1 sparing are not tied to a location but represent a central deficit, in line with current theory.     

Delayed attentional engagement in the attentional blink

Observers often miss the 2nd of 2 visual targets (first target [T1] and second target [T2]) when these targets are presented closely in time; the attentional blink (AB). The authors hypothesized that the AB occurs because the attentional response to T2 is delayed by T1 processing, causing T2 to lose a competition for attention to the item that follows it. The authors investigated this hypothesis by determining whether the AB is attenuated when T2 is precued. The results from 4 experiments showed that the duration and magnitude of the AB were substantially reduced when T2 was precued. The observed improvement in T2 report did not occur at the expense of T1 report, suggesting that processing of T1 was already completed or was at least protected when the cue was presented. The authors conclude that, during the AB, there is a delay between detection and the selection of target candidates for consolidation in short-term memory.     

The attentional blink

When two masked targets (T1 and T2) are presented within approximately 500 ms of each other, subjects are often unable to report the second of the two targets (T2) accurately, even though the first has been reported correctly. In contrast, subjects can report T2 accurately when instructed to ignore T1, or when T1 and T2 are separated by more than 500 ms. The above pattern of results has been labelled the attentional blink (AB). Experiments have revealed that the AB is not the result of perceptual, memory or response output limitations. In general, the various theories advanced to account for the AB, although they differ in the specific mechanisms purported to be responsible, assume that allocating attention to T1 leaves less attention for T2, rendering T2 vulnerable to decay or substitution. The present report attempts to bring together these various accounts by proposing a unifying theory. This report also highlights recent attempts to determine if the AB exists across stimulus modalities and points to applications of AB methods in understanding deficits of visual neglect. We conclude by suggesting that investigations of the AB argue in favour of the view that attention may be thought of as a necessary (but not sufficient) condition for enabling consciousness.     

Temporal selection is suppressed, delayed, and diffused during the attentional blink

How does temporal selection work, and along what dimensions does it vary from one instance to the next? We explored these questions using a phenomenon in which temporal selection goes awry. In the attentional blink, subjects fail to report the second of a pair of targets (T1 and T2) when they are presented at stimulus onset asynchronies (SOAs) of roughly 200 to 500 ms. We directly tested the properties of temporal selection during the blink by analyzing distractor intrusions at a fast rate of item presentation. Our analysis shows that attentional selection is (a) suppressed, (b) delayed, and (c) diffused in time during the attentional blink. These effects are dissociated by their time course: The measure of each effect returns to the baseline value at a different SOA. Our results constrain theories of the attentional blink and indicate that temporal selection varies along at least three dissociable dimensions: efficacy, latency, and precision.     

Exploring attentional disruption in fibromyalgia using the attentional blink

Disrupted attentional function in individuals with fibromyalgia syndrome (FMS) has been noted in a number of previous studies. The cognitive mechanisms related to this disruption are not well-understood. This study sought to identify whether differences exist in early attentional processing and attentional capacity in individuals with FMS measuring the attentional blink (AB). Early attentional function was assessed in 16 females with FMS and compared with 16 healthy age-matched females without FMS. Simple early visual stimulus target detection accuracy was not significantly different between groups. However, as target detection difficulty increased, individuals in the FMS group showed significantly poorer performance compared to healthy participants. Our findings suggest that attentional disruption in individuals with FMS is associated with deficits in the early allocation of attentional resources during the completion of tasks with higher attentional demand.     

Target integration and the attentional blink

If people monitor a visual stimulus stream for targets they often miss the second (T2) if it appears soon after the first (T1)--the attentional blink. There is one exception: T2 is often not missed if it appears right after T1, i.e., at lag 1. This lag-1 sparing is commonly attributed to the possibility that T1 processing opens an attentional gate, which may be so sluggish that an early T2 can slip in before it closes. We investigated why the gate may close and exclude further stimuli from processing. We compared a control approach, which assumes that gate closing is exogenously triggered by the appearance of nontargets, and an integration approach, which assumes that gate closing is under endogenous control. As predicted by the latter but not the former, T2 performance and target reversals were strongly affected by the temporal distance between T1 and T2, whereas the presence or the absence of a nontarget intervening between T1 and T2 had little impact.     

Exploring attentional disruption in fibromyalgia using the attentional blink

Disrupted attentional function in individuals with fibromyalgia syndrome (FMS) has been noted in a number of previous studies. The cognitive mechanisms related to this disruption are not well-understood. This study sought to identify whether differences exist in early attentional processing and attentional capacity in individuals with FMS measuring the attentional blink (AB). Early attentional function was assessed in 16 females with FMS and compared with 16 healthy age-matched females without FMS. Simple early visual stimulus target detection accuracy was not significantly different between groups. However, as target detection difficulty increased, individuals in the FMS group showed significantly poorer performance compared to healthy participants. Our findings suggest that attentional disruption in individuals with FMS is associated with deficits in the early allocation of attentional resources during the completion of tasks with higher attentional demand.     

Goal-completion processes affect the attentional blink

People are notably limited in processing information from the outside world. For instance, they frequently fail to identify the second of two targets presented in close succession (attentional blink, AB). Theories of the AB have mostly focused upon early stimuli processing. However, here we show that late, goal-completion processes play an important role. We report findings from a rapid serial visual presentation task with three targets (T1, T2, and T3). Participants set to achieve one single goal for T1 and T2 (reporting the sum of the two), and to detect T3, showed an AB effect upon T3 but not upon T2, while participants set to achieve separate goals for the three targets showed an AB effect upon both T2 and T3. This finding raises questions about the nature of AB, suggesting that theories of the AB must take into account processes involved in goal switching.     

Parameterizing the attentional blink effect.

The attentional blink effect (AB) is used to examine the limits of attention in dual-task paradigms. However, since the effect is nonlinear, it is sometimes difficult to characterize the results. Furthermore, it is difficult to assess the significance of the effect between groups because the results are highly variable both within and across subjects. In this paper, we propose a method to quantify four characteristics of the AB curve: the minimum performance, the amplitude between the minimum and the asymptotic performance, the amount of Lag-1 sparing, and the width of the effect. The method, based on curve fitting, allows easier comparisons of the results across experiments, can test only one characteristic at a time, and yields more powerful statistical tests.     

No commonality between attentional capture and attentional blink

Visual search for a unique target is impaired when a salient distractor is presented (attentional capture). This phenomenon is said to occur because attention is diverted to a distractor before it reaches the target. Similarly, perception of the second of two targets embedded in a rapid stream of nontargets is impaired, suggesting attentional deprivation due to the processing of the first target (attentional blink). We examined whether these phenomena emerge from a common underlying attentional mechanism by using correlation studies. If these phenomena share a common foundation, the magnitude of these deficits should show within-subject correlations. Participants (N = 135) revealed significant attentional deficits during spatial and temporal capture and the attentional blink tasks. However, no significant correlation was found among these tasks. Experiment 2 (N = 95) replicated this finding using the same procedure as that used in Experiment 1 but included another attentional blink task that required spatial switching between the two targets. Strong correlations emerged only between the two attentional blink tasks (with/without spatial switching). The present results suggest that attentional deficits during spatial and temporal capture and the attentional blink tasks reflect different aspects of attention.     

Representational masking and the attentional blink

After successful detection of a target item within a stream of rapidly displayed visual stimuli, subsequent detection of an additional target is impaired for roughly 500 ms. This impairment is known as the “attentional blink” (AB). Previous studies have found that if either the first (Tl; Raymond, Shapiro, & Arnell, 1992) or second target (T2; Giesbrecht & Di Lollo, 1998) is not followed by a mask, the AB impairment is significantly reduced. Whereas low-level perceptual factors have been found to influence the efficacy of masking in the AB (e.g., Seiffert & Di Lollo, 1997), the current experiment used a higher level (representational) manipulation, i.e., repetition blindness to reduce the efficacy of target masking in the AB. These findings contribute to the growing literature suggesting that masking plays more than a perceptual role in the AB phenomenon.     

Distraction and the auditory attentional blink

When two target stimuli (T1 and T2) are presented in close succession within a stimulus sequence, detection or discrimination performance for T2 is often impaired; this phenomenon is called the attentional blink (AB). Growing evidence suggests that the AB is present not only for visual, but also for auditory stimuli. Because sounds have a strong potential to attract attention when they are presented after longer silent intervals or in a sequence from which they stand out because of their rare or novel physical features, it seems possible that the involuntary and excessive allocation of attention to T1 (distraction) may contribute to the AB. By varying the saliency of T1, we showed that distraction does contribute to the auditory AB effect, but the contribution is short-lived: Only stimuli immediately following T1 are affected.     

Summary statistics in the attentional blink

We used the attentional blink (AB) paradigm to investigate the processing stage at which extraction of summary statistics from visual stimuli (“ensemble coding”) occurs. Experiment 1 examined whether ensemble coding requires attentional engagement with the items in the ensemble. Participants performed two sequential tasks on each trial: gender discrimination of a single face (T1) and estimating the average emotional expression of an ensemble of four faces (or of a single face, as a control condition) as T2. Ensemble coding was affected by the AB when the tasks were separated by a short temporal lag. In Experiment 2, the order of the tasks was reversed to test whether ensemble coding requires more working-memory resources, and therefore induces a larger AB, than estimating the expression of a single face. Each condition produced a similar magnitude AB in the subsequent gender-discrimination T2 task. Experiment 3 additionally investigated whether the previous results were due to participants adopting a subsampling strategy during the ensemble-coding task. Contrary to this explanation, we found different patterns of performance in the ensemble-coding condition and a condition in which participants were instructed to focus on only a single face within an ensemble. Taken together, these findings suggest that ensemble coding emerges automatically as a result of the deployment of attentional resources across the ensemble of stimuli, prior to information being consolidated in working memory.     

No commonality between attentional capture and attentional blink

Visual search for a unique target is impaired when a salient distractor is presented (attentional capture). This phenomenon is said to occur because attention is diverted to a distractor before it reaches the target. Similarly, perception of the second of two targets embedded in a rapid stream of nontargets is impaired, suggesting attentional deprivation due to the processing of the first target (attentional blink). We examined whether these phenomena emerge from a common underlying attentional mechanism by using correlation studies. If these phenomena share a common foundation, the magnitude of these deficits should show within-subject correlations. Participants (N?=?135) revealed significant attentional deficits during spatial and temporal capture and the attentional blink tasks. However, no significant correlation was found among these tasks. Experiment 2 (N?=?95) replicated this finding using the same procedure as that used in Experiment 1 but included another attentional blink task that required spatial switching between the two targets. Strong correlations emerged only between the two attentional blink tasks (with/without spatial switching). The present results suggest that attentional deficits during spatial and temporal capture and the attentional blink tasks reflect different aspects of attention.     

Attentional control in the attentional blink is modulated by odor

Increasing evidence suggests that `aromas have distinctive effects on the allocation of attention in space: Arousing olfactory fragrances (e.g., peppermint) are supposed to induce a more focused state, and calming olfactory fragrances (e.g., lavender) a broader attentional state. Here, we investigate whether odors have similar effects on the allocation of attention in time. Participants performed the attentional blink (AB) task, known to produce a deficit in reporting the second of two target stimuli presented in close succession in a rapid sequence of distractors, while being exposed to either a peppermint or a lavender aroma. In two experiments using a between-subjects and a within-subjects design, respectively, we show that the two odors have specific effects on attentional control: As compared with the calming lavender aroma, the arousing peppermint condition yielded a larger AB. Our results demonstrate that attentional control is systematically modulated by factors that induce a more or a less distributed state of mind.     

Modulation of the attentional blink by differential resource allocation.

When one masked target (T2) follows another (T1) in close temporal proximity, identification accuracy of the second target is reduced for a period referred to as the attentional blink. Analysis of the attentional blink literature suggests that increasing the difficulty of T1 processing increases the magnitude of the blink. In a previous study that eliminated several untoward features of the typical attentional blink design (e.g., task switching, location switching, and stream contribution), we found no effect on blink magnitude when three levels of T1 difficulty (manipulated in a data-limited manner) were randomly intermixed. Here, when we repeated the previous study using a blocked manipulation of T1 difficulty, which is characteristic of the literature, a significant positive relation between T1 difficulty and blink magnitude was found. Resource allocation put in place to encode T1 in advance of a dual-target trial thus seems to be the critical factor in mediating this relation.     

Impaired temporal discrimination within the attentional blink

Yeshurun and Levy (2003) reported that temporal discrimination performance of a visual stimulus benefits when spatial attention is oriented away from its location. In the present study, we investigated whether this negative influence of attention on temporal discrimination performance is restricted to transient spatial attention or might generalize to other paradigms of attention. We employed the attentional blink (AB) paradigm and required either a spatial (Experiment 1) or a temporal discrimination task (Experiment 2). The results of both experiments revealed a performance decrement if attention was temporally unavailable during the AB and a recovery with increasing attentional availability. Thus, contrary to the results of Yeshurun and Levy, the absence of attention decreased temporal discrimination performance in this paradigm. We hypothesize that attention which operates at different processing levels might exert differential effects on temporal stimulus processing.     

Objects and events in the attentional blink

When two visual targets, T1 and T2, are presented in rapid succession, detection or identification of T2 is almost universally degraded by the requirement to attend to T1 (the attentional blink, or AB). One interesting exception occurs when T1 is a brief gap in a continuous letter stream and the task is to discriminate its duration. One hypothesized explanation for this exception is that an AB is triggered only by attention to a patterned object. The results reported here eliminate this hypothesis. Duration judgments produced no AB whether the judged duration concerned a short gap in the letter stream (Experiment 1) or a letter presented for slightly longer than others (Experiment 2). When identification of an identical longer letter T1 was required (Experiment 3), rather than a duration judgment, the AB was reestablished. Direct perceptual judgments of letter streams with gaps embedded showed that whereas brief gaps result in the percept of a single, briefly hesitating stream, longer gaps result in the percept of two separate streams with a separating pause. Correspondingly, an AB was produced in Experiment 4, when participants were required to judge the duration of longer T1 gaps. We propose that, like spatially separated objects, temporal events are parsed into discrete, hierarchically organized events. An AB is triggered only when a new attended event is defined, either when a long pause creates a new perceived stream (Experiment 4) or when attention shifts from the stream to the letter level (Experiment 3).