Rapid Serial Visual Presentation Stream Research Articles

Event-Related Potential Evidence for Two Functionally Dissociable Sources of Semantic Effects in the Attentional Blink

Three target words (T1, T2, and T3) were embedded in a rapid serial visual presentation (RSVP) stream of non-word distractors, and participants were required to report the targets at the end of each RSVP stream. T2 and T3 were semantically related words in half of the RSVP streams, and semantically unrelated words in the other half of the RSVP streams. Using an identical design, a recent study reported distinct reflections of the T2–T3 semantic relationship on the P2 and N400 components of event-related potentials (ERPs) time-locked to T3, suggesting an early, automatic, source of P2 semantic effects and a late, controlled, source of N400 semantic effects. Here, P2 and N400 semantic effects were examined by manipulating list-wide context. Relative to participants performing in a semantically unbiased context, participants over-exposed to filler RSVP streams always including semantically related T2/T3 words reported a dilution of T3-locked P2 semantic effects and a magnification of T3-locked N400 semantic effects. Opposite effects on P2 and N400 ERP components of list-wide semantic context are discussed in relation to recent proposals on the representational status of RSVP targets at processing stages prior to consolidation in visual short-term memory.

Sources of bias and uncertainty in a visual temporal individuation task

Despite a clear ability to detect temporal modulations of visual stimuli in excess of 50 Hz, temporal individuation and serial order judgment tasks can be performed only when stimuli alternate at much slower rates, and the nature of such sluggishness remains unclear. One example of a task with a slow temporal limit is the individuation of a cued letter in a rapid serial visual presentation (RSVP) stream. The present study investigates the nature of the code used to perform such a slow temporal individuation task and the sources of uncertainty involved. The results demonstrate that temporal, rather than ordinal, position in the RSVP stream is critical in serial order estimation, suggesting the involvement of a noisy temporal code. In addition to variability in temporal coding, observers' choices are also limited by a number of other factors, such as categorical errors and biases related to the position of the cue in the letters' stream. Attentional filtering improves categorization, but crucially, it does not seem to increase the temporal precision of judgment. Generalizing the present results, I suggest that perception of order is limited by an internal temporal sampling instability that is distinct and independent from attention and that, similarly to temporal jitter in a clock, acts as a low-pass filter that hinders the judgment of the order of events that unfold too quickly.

On the Precision of Attention Sets: The Effects of Spatial Context and Distractor Multiplicity on Contingent Capture

The contingent spatial blink paradigm, developed by Folk, Leber, and Egeth (2002), demonstrates a deficit in precision when maintaining attention goals (sets). A completely irrelevant target-colored distractor presented with an RSVP (rapid serial visual presentation) stream induces a substantial attention capture effect, even when this distractor is distant from the RSVP stream and the target’s location is central and constant. We first performed an experiment to determine whether attention set precision could be improved by providing spatial context. The target and target-colored distractor either both appeared within one of two boundary boxes or in separate boxes. We hypothesized that when the target and same-color distractor were separated by spatial context, capture would be diminished. Supporting this hypothesis, results show that capture was reduced when the items were separated (M = 71.7% accuracy) compared to when they appeared within the same box (M = 63.4%), but this contextual exclusion was not sufficient enough to fully eliminate capture. Our second experiment examined whether holding an attention set for both color and number, since the target is a single red item, would prevent capture when multiple target-colored distractors were introduced. On critical trials, one target-colored distractor could appear at a random peripheral location, two such distractors could appear at adjacent locations, or these two distractors could appear at opposite locations. We hypothesized that multiple target-colored distractors would produce less capture than a single target-colored distractor since they do not fulfill the characteristic of oneness. Results revealed that adjacently positioned distractors (M = 62.4%) and oppositely positioned top-bottom distractors (M = 60.5%) behaved similarly to a single distractor (M = 64.0%). Surprisingly, opposite left-right (M = 52.8%) distractors actually produced greater capture. Both experiments demonstrate the limitation of attention set precision, but show how spatial and contextual factors can modulate contingent capture. Meeting abstract presented at VSS 2012

Analogue trauma results in enhanced encoding of threat information at the expense of neutral information

This study investigated whether trauma-related stimuli are preferentially processed at the expense of ongoing processing of neutral stimuli. Participants in the experimental group viewed negative pictures (Trauma) as an analogue trauma induction. Participants in the control group viewed visually similar neutral pictures (Neutral Match). In a Rapid Serial Visual Presentation (RSVP) task participants identified two target pictures. The first target (T1) was a neutral picture, whereas the second target (T2) was a familiar negative or neutral picture or a new neutral or negative picture. In line with hypotheses, only participants in the experimental group showed preferential processing of Trauma pictures. In the experimental group, negative T2 impaired the identification of (neutral) T1 if the T2 immediately followed the T1 in the RSVP stream. The results are consistent with a processing priority of trauma-related information, apparently at the expense of the ongoing processing of neutral information.

Preferential processing of threatening facial expressions using the repetition blindness paradigm

Background: Neuroanatomical evidence suggests that the human brain has dedicated pathways to rapidly process threatening stimuli. This processing bias for threat was examined using the repetition blindness (RB) paradigm. RB (i.e., failure to report the second instance of an identical stimulus rapidly following the first) has been established for words, objects and faces but not, to date, facial expressions. Methods: 78 (Study 1) and 62 (Study 2) participants identified repeated and different, threatening and non-threatening emotional facial expressions in rapid serial visual presentation (RSVP) streams. Results: In Study 1, repeated facial expressions produced more RB than different expressions. RB was attenuated for threatening expressions. In Study 2, attenuation of RB for threatening expressions was replicated. Additionally, semantically related but non-identical threatening expressions reduced RB relative to non-threatening stimuli. Conclusions: These findings suggest that the threat bias is apparent in the temporal processing of facial expressions, and expands the RB paradigm by demonstrating that identical facial expressions are susceptible to the effect.

Attentional control: Temporal relationships within the fronto-parietal network

Selective attention to particular aspects of incoming sensory information is enabled by a network of neural areas that includes frontal cortex, posterior parietal cortex, and, in the visual domain, visual sensory regions. Although progress has been made in understanding the relative contribution of these different regions to the process of visual attentional selection, primarily through studies using neuroimaging, rather little is known about the temporal relationships between these disparate regions. To examine this, participants viewed two rapid serial visual presentation (RSVP) streams of letters positioned to the left and right of fixation point. Before each run, attention was directed to either the left or the right stream. Occasionally, a digit appeared within the attended stream indicating whether attention was to be maintained within the same stream (‘hold’ condition) or to be shifted to the previously ignored stream (‘shift’ condition). By titrating the temporal parameters of the time taken to shift attention for each participant using a fine-grained psychophysics paradigm, we measured event-related potentials time-locked to the initiation of spatial shifts of attention. The results revealed that shifts of attention were evident earlier in the response recorded over frontal than over parietal electrodes and, importantly, that the early activity over frontal electrodes was associated with a successful shift of attention. We conclude that frontal areas are engaged early for the purpose of executing an attentional shift, likely triggering a cascade through the fronto-parietal network ultimately, resulting in the attentional modulation of sensory events in posterior cortices.

Sparing from the attentional blink is not spared from structural limitations

When a series of three successive to-be-reported items (targets) is displayed in a rapid serial visual presentation (RSVP) stream of distractors, it has been shown that no attentional blink--a marked impairment in the report of the second of two targets, typically observed when the targets appear within 200-600 ms of one another--occurs in target accuracy. The present study examines three recently introduced computational models that provide different explanations of this protracted sparing effect. Using a standard RSVP design and these models, we provide empirical data and simulations that illustrate that structural limitations affect the processing of successive targets. In addition, we compare the candidate mechanisms that might underlie these limitations.

Perception of temporal order is impaired during the time course of the attentional blink.

Identification accuracy for the second of two target (T2) is impaired when presented shortly after the first (T1). Does this attentional blink (AB) also impair the perception of the order of presentation? In four experiments, three letter targets (T1, T2, T3) were inserted in a stream of digit distractors displayed in rapid serial visual presentation (RSVP), with T3 always presented directly after T2. The T1-T2 lag was varied to assess the perception of T2-T3 temporal order throughout the period of the AB. Factorial manipulation of the presence or absence of distractors before T1 and between T1 and T2 had similar effects on accuracy and on perception of temporal order. It is important to note that perception of temporal order suffered even when accuracy was unimpaired. This pattern of results is consistent with prior-entry theories of the perception of temporal order but not with episodic-integration theories. Simulations based on the Episodic Simultaneous Type, Serial Token (eSTST) model (Wyble, Bowman, & Nieuwenstein, 2009) provided excellent fits to the data except for the condition in which no distractors were presented in the RSVP stream.

Attentional Selection Dilates Perceived Duration

How do observers judge the passage of time at a short time-scale? Humans are not equipped with a dedicated sensory system for perceiving durations in the same way as they are equipped with systems for perceiving light and sound. Thus, subjective duration depends on the sensory and cognitive processes triggered by sensory input, eg visual or auditory stimuli. Previous studies have demonstrated that the dynamics of this sensory input (eg the rate of stimulus presentation) affect duration judgments. However, it is yet unclear whether automatic or attentive processing of such dynamics accounts for their effect on subjective duration. Automatic and attentive stimulus processing can be distinguished when stimuli are presented in a rapid serial visual presentation (RSVP) paradigm. The second of two targets embedded in an RSVP stream often fails to attract participants' attention and escapes conscious detection, in spite of being automatically processed at a perceptual level. In the present study, we presented RSVP streams and combined a target detection task with a prospective duration judgment task. We demonstrate in three experiments that the number of subjectively perceived target stimuli (and not the number of objectively presented targets) determines subjective duration of the entire RSVP sequence. Target stimuli which escape attentional selection did not affect perceived duration. This finding indicates that attentive rather than automatic processing of stimulus dynamics leads to the subjective time dilation of dynamic stimuli.

Repetition blindness reveals differences between the representations of manipulable and nonmanipulable objects.

We used repetition blindness to investigate the nature of the representations underlying identification of manipulable objects. Observers named objects presented in rapid serial visual presentation streams containing either manipulable or nonmanipulable objects. In half the streams, 1 object was repeated. Overall accuracy was lower when streams contained 2 different manipulable objects than when they contained only nonmanipulable objects or a single manipulable object. In addition, nonmanipulable objects induced repetition blindness, whereas manipulable objects were associated with a repetition advantage. These findings suggest that motor information plays a direct role in object identification. Manipulable objects are vulnerable to interference from other objects associated with conflicting motor programs, but they show better individuation of repeated objects associated with the same action.

RSVP in orbit: Identification of single and dual targets in motion

Three experiments using rapid serial visual presentation (RSVP) tested participants' ability to detect targets in streams that are in motion. These experiments compared the ability to identify moving versus stationary RSVP targets and examined the attentional blink with pairs of targets that were moving or stationary. One condition presented RSVP streams in the center of the screen; a second condition used an RSVP that was orbiting in a circle, with participants instructed to follow the stream with their eyes; and a third condition had participants fixate in the middle while observing a circling RSVP stream. Relative to performance in stationary RSVP streams, participants were not markedly impaired in detecting single targets in RSVP streams that were moving, either with or without instructions to pursue the motion. In streams with two targets, a normal attentional blink effect was observed when participants were instructed to pursue the moving stream. When participants had to maintain central fixation as the RSVP stream moved, the attentional blink was nearly absent even when a trailing mask was added. We suggest that the reduction of the attentional blink for moving RSVP streams may reflect a reduced ability to perceive the temporal boundaries of the individual items.

Target sparing effects in the attentional blink depend on type of stimulus

In a typical attentional blink (AB) experiment, recognition of the second of two serially presented targets is impaired if it occurs around 200-500 ms after the first. However, recognition for the second item is often intact if the two targets occur consecutively (lag-1 sparing). Recent theories of the AB have placed great emphasis on the presence of lag-1 sparing and protracted sparing effects, where accurate performance is seemingly maintained across three or more targets, provided that they are presented consecutively. Here, we show that the type of stimulus (objects vs. letters) used in rapid serial visual presentation streams has a significant effect on the extent of lag-1 sparing, without a commensurate influence on the AB. In addition, multiple consecutive targets produce strikingly different patterns of sparing for objects and letters. These findings suggest that the processes mediating lag-1 sparing are independent of those underlying the AB.

Inhibition from blinked category labels: Combining the attentional blink and the semantic priming paradigm

In the present experiment we combined the attentional blink and the semantic priming paradigm. We used category labels as primes and category exemplars as targets. The prime stimuli were embedded into a rapid serial visual presentation (RSVP) stream and presented at varying positions after a to-be-identified stimulus, albeit the stimulus–onset asynchrony between primes and targets remained constant throughout the experiment. As a result, participants’ prime awareness was reduced in some trials although the prime duration was always at levels usually considered to elicit awareness (60 ms). After each RSVP there was a forced choice discrimination test to assess participants’ prime awareness. When subjects could not identify the prime stimuli we observed slower responses to related as compared to unrelated targets. This result confirms results found with repeated masked primes. However, whereas former studies assessed unawareness rather coarsely at the level of individual participants, here unawareness was tested on a trial-by-trial basis.

Failures of Visual Awareness: Inattentional Blindness and Attentional Blink

Failures of visual awareness occur when attentional processing limitations prevent an observer from detecting clearly visible stimuli. These failures can occur in a variety of contexts; two well-known research examples are inattentional blindness (IB) and attentional blink (AB). IB involves failure to detect an irrelevant, unexpected stimulus when attention is engaged by another primary task. AB involves failure to detect a relevant, expected stimulus, which occurs when a second target is presented within 180–500ms of the first target in a rapid serial visual presentation stream. Because both involve failures of visual awareness, IB and AB are often discussed in conjunction with each other. Though past research has implicated similar cognitive processes underlying both phenomena, no evidence directly correlated the two. We tested 54 observers on both an IB task and an AB task. Consistent with our hypotheses, we found that “non-noticers” who failed to detect an unexpected stimulus in the IB task also demonstrated larger AB magnitude, with a particular dip at lag 2, compared with noticers of the unexpected stimulus. This suggests that individual differences play a role in failures of visual awareness and that some observers may be more or less susceptible to failures of visual awareness generally.

Unique sudden onsets capture attention even when observers are in feature-search mode

Two sources of attentional capture have been proposed: stimulus-driven (exogenous) and goal-oriented (endogenous). A resolution between these modes of capture has not been straightforward. Even such a clearly exogenous event as the sudden onset of a stimulus can be said to capture attention endogenously if observers operate in singleton-detection mode rather than feature-search mode. In four experiments we show that a unique sudden onset captures attention even when observers are in feature-search mode. The displays were rapid serial visual presentation (RSVP) streams of differently coloured letters with the target letter defined by a specific colour. Distractors were four #s, one of the target colour, surrounding one of the non-target letters. Capture was substantially reduced when the onset of the distractor array was not unique because it was preceded by other sets of four grey # arrays in the RSVP stream. This provides unambiguous evidence that attention can be captured both exogenously and endogenously within a single task.

Emotional modulation of the attentional blink: The neural structures involved in capturing and holding attention

Perceiving a first target stimulus (T1) in a rapid serial visual presentation stream results in a transient impairment in detecting a second target (T2). This “attentional blink” is modulated by the emotional relevance of T1 and T2. The present experiment examined the neural underpinnings of the emotional modulation of the attentional blink. Behaviorally, the attentional blink was reduced for emotional T2 while emotional T1 led to a prolonged attentional blink. Using functional magnetic resonance imaging, we observed amygdala activation associated with the reduced attentional blink for emotional T2 in the face of neutral T1. The prolonged attentional blink following emotional T1 was correlated with enhanced activity in a cortical network including the anterior cingulate cortex, the insula and the orbitofrontal cortex. These results suggest that brain areas previously implicated in rather reflexive emotional reactions are responsible for the reduced attentional blink for emotional T2 whereas neural structures previously related to higher level processing of emotional information mediate the prolonged attentional blink following emotional T1.

Attentional blink and repetition blindness.

When two masked, to-be-attended targets are presented within half a second of each other, report accuracy for the second target (T2) is impaired relative to when the two targets are presented farther apart in time or relative to when the first target (T1) can be ignored. This effect is known as the attentional blink (AB). An additional T2 accuracy deficit is observed if T1 and T2 are identical or highly similar on a task-relevant dimension. This effect is known as repetition blindness (RB). For both AB and RB, targets are typically imbedded in rapid serial visual presentation (RSVP) streams and the dual-task attention cost lasts approximately half a second. Given the high degree of superficial similarity, AB and RB are often considered to be related phenomena. Although research thus far has suggested that both phenomena reflect limits of the attentional system and how attention is allocated when needing to organize stimuli for entrance into awareness, these two phenomena are dissociable; RB is not simply an enhanced AB. Furthermore, investigations of AB and RB have taken quite different courses over the last two decades. The AB has been investigated extensively with a variety of experimental, behavioral, neurophysiological, and clinical approaches, and has become widely used as a paradigm of convenience with which to study other effects. In contrast, studies of RB have tended to manipulate the nature of the target information to understand the level of representation that supports RB. WIREs Cogni Sci 2011 2 336-344 DOI: 10.1002/wcs.129 For further resources related to this article, please visit the WIREs website.

On the role of intervening distractors in the attentional blink

The attentional blink (AB) refers to the decline in accurate report for a second target (T2) when presented within about 500ms of a first target (T1) embedded in a rapid serial visual presentation stream of distractors. It is debated whether the distractors presented shortly after T1 cause the AB directly, as is proposed by distractor-based models, or can modulate its amplitude only indirectly by increasing T1 difficulty, as is proposed by capacity-based models. To investigate this issue, an intervening distractor was presented at lag 1 (T1 + 1), at lag 2 (T1 + 2), or at neither of these two lags (no distractor). T2 was presented at either lag 3 or 9. An AB was observed even in the absence of intervening distractors, indicating that distractors are not necessary to produce an AB. Nonetheless, the T1 + 2 distractor did modulate the AB directly, without influencing T1 performance. Neither theory can fully account for the results but can do so given some modifications.

Differential effects of exogenous and endogenous cueing in multi-stream RSVP: implications for theories of attentional blink

The attentional blink (AB) refers to the finding that performance on the second of two targets (T1 and T2) in a rapid serial visual presentation (RSVP) stream is impaired when the targets are presented within 200–500 ms. To explore the possible interaction between spatial attentional orienting and temporary attentional deficits, this study used central (endogenous) and peripheral (exogenous) cues in a multi-stream RSVP task and compared the endogenous and exogenous cueing effects inside and outside of the AB period. While the endogenous cueing effect was constant in magnitude over time, the exogenous cueing effect was significantly larger inside than outside of the AB period. Theoretical implications of these findings for the interaction between attention mechanisms in spatial and temporal domains are discussed.

Individual differences in dispositional focus of attention predict attentional blink magnitude

When identifying two targets presented in a rapid serial visual presentation stream, one's accuracy on the second target is reduced if it is presented shortly (within 500 msec) after the first target-an attentional blink (AB). Individuals differ greatly in the size of their AB. One way to learn about the AB is to understand what underlies these individual differences. Recent studies have suggested that when a broadened or diffused attentional state is induced, the AB deficit can be attenuated. The present study examined whether natural (dispositional) individual differences in focus and diffusion of attention as assessed by the global/local task could predict performance on the AB task. Performance that was consistent with diffusion correlated negatively with AB size, and performance that was consistent with focusing correlated positively with AB size, showing that dispositional focus and diffusion of attention can predict individual differences in the AB. These findings are consistent with the Olivers and Nieuwenhuis (2006) overinvestment hypothesis.