Electrophysiological modulations of exogenous attention by intervening events

The present study used event related potentials (ERPs) in a spatial cueing procedure to investigate the stages of processing influenced by intervening events presented between cues and targets, when they produce maximal behavioural modulations (i.e., facilitation in the absence of the intervening event, and inhibition of return – IOR, when the intervening event is presented). Our data challenge the traditional orienting–reorienting hypothesis, leading to alternative explanations of cueing effects that are beyond the orienting of attention. Peripheral cues always produced a detection cost (reflected in a reduced amplitude of the P100 component for cued as compared to uncued trials), independently on the behavioural effect that was measured. In contrast, facilitation was associated to modulations of later-stage components, such as N100, Nd, and P300. The N2pc component, usually associated to spatial selection, was the only component reflecting opposite and significant modulations associated to the behavioural effect. The present results suggest that facilitation and IOR can arise from changes at different stages of processing. We propose that the perceptual detection cost (reflected on the P100), and the hindered spatial selection (reflected on the N2pc) at the cued location determine the IOR effect at least in discrimination tasks, while the contribution of the later-stage components, beside attentional processes, determines other facilitatory effects of cueing, which altogether determine the behavioural effect that is measured.     

Allocation of visual attention to spatial locations: tradeoff functions for event-related brain potentials and detection performance

Event-related brain potentials (ERPs) were recorded in response to unilateral arrays of letters flashed in rapid, randomized sequences to left and right visual field locations. Subjects were required to focus attention exclusively on either left or right field stimuli, or to divide attention in different proportions between the two fields, with the aim of detecting infrequent target letters. Both d' and percent hits for target detections increased significantly as attentional allocation to a stimulus location increased. Attention operating characteristic (AOC) curves for the target detection scores were highly similar in form to those for the amplitudes of the long-latency, endogenous ERP components--N350-650 and P400-800 (P300). All of these measures showed gradual, nearly rectangular tradeoff functions. In contrast, the AOC curves for the early sensory-evoked components displayed steep, nearly linear amplitude tradeoffs as attention was increasingly allocated to one visual field at the expense of the other. The early and late ERP components were considered as indices of separate but interacting levels of attentional selection having different operating principles.     

Shifts of spatial attention cued by irrelevant numbers: Electrophysiological evidence from a target discrimination task

Fischer et al. demonstrated that a centrally presented number can shift attention to the left/right when its magnitude is small/large. Two electrophysiological studies described these attentional effects as event-related potentials (ERPs) at centro-parietal sites. Since both studies used target detection tasks, it remains currently unknown whether similar results would be obtained with a discrimination task. We used ERPs to test whether digit cues also induce attention shifts when participants perform a feature-discrimination task on targets. ERPs were recorded whereas subjects discriminated the colour of lateral targets that were preceded by a central non-predictive digit. Analysis of cue-locked controlateral vs. ipsilateral ERP activity showed the emergence of early preparatory attention-directing components in parietal and frontal regions. Moreover, target-locked P1 components at occipito-parietal sites were significantly modulated by digit magnitude-target side congruency. These results demonstrate that irrelevant digit cues also bias sensory processing when embedded in a feature-discrimination task.     

Frontal cortex electrophysiology in reward- and punishment-related feedback processing during advice-guided decision making: An interleaved EEG-DC stimulation study

During decision making, individuals are prone to rely on external cues such as expert advice when the outcome is not known. However, the electrophysiological correlates associated with outcome uncertainty and the use of expert advice are not completely understood. The feedback-related negativity (FRN), P3a, and P3b are event-related brain potentials (ERPs) linked to dissociable stages of feedback and attentional processing during decision making. Even though these ERPs are influenced by both reward- and punishment-related feedback, it remains unclear how extrinsic information during uncertainty modulates these brain potentials. In this study, the effects of advice cues on decision making were investigated in two separate experiments. In the first experiment, electroencephalography (EEG) was recorded in healthy volunteers during a decision-making task in which the participants received reward or punishment feedback preceded by novice, amateur, or expert advice. The results showed that the P3a component was significantly influenced by the subjective predictive value of an advice cue, whereas the FRN and P3b were unaffected by the advice cues. In the second, sham-controlled experiment, cathodal transcranial direct current stimulation (ctDCS) was administered in conjunction with EEG in order to explore the direct contributions of the frontal cortex to these brain potentials. Results showed no significant change in either advice-following behavior or decision times. However, ctDCS did decrease FRN amplitudes as compared to sham, with no effect on the P3a or P3b. Together, these findings suggest that advice information may act primarily on attention allocation during feedback processing, whereas the electrophysiological correlates of the detection and updating of internal prediction models are not affected.     

Sensory ERP effects in auditory distraction: did we miss the main event?

Event-related potentials (ERPs) offer unique insights into processes related to involuntary attention changes triggered by rare, unpredictably occurring sensory events, that is, distraction. Contrasting ERPs elicited by distracters and frequent standard stimuli in oddball paradigms allowed the formulation of a three-stage model describing distraction-related processing: first, the distracting event is highlighted by a sensory filter. Second, attention is oriented towards the event, and finally, the task-optimal attention set is restored, or task priorities are changed. Although this model summarizes how distracting stimulus information is processed, not much is known about the cost of taking this exceptional route of processing. The present study demonstrates the impact of distraction on sensory processing. Participants performed a Go/NoGo tone-duration discrimination task, with infrequent pitch distracters. In the two parts of the experiment the duration-response mapping was reversed. Contrasts of distracter and standard ERPs revealed higher P3a- and reorienting negativity amplitudes for short than for long tones, independently from response type. To understand the cause of these asymmetries, short vs. long ERP contrasts were calculated. The ERP pattern showed that short standards elicited an attention-dependent offset response, which was abolished for short distracters. That is, the apparent P3a- and RON enhancements were caused by the removal of a task-related attentional sensory enhancement. This shows that the disruption of task-optimal attention set precedes the elicitation of the P3a, which suggests that P3a does not reflect a process driving the initial distraction-related attention change.     

Inference-driven attention in symbolic and perceptual tasks: biases toward expected and unexpected inputs

The aims of this paper are (a) to gather support for the hypothesis that some basic mechanisms of attentional deployment (i.e., its high efficiency in dealing with expected and unexpected inputs) meet the requirements of the inferential system and have possibly evolved to support its functioning, and (b) to show that these orienting mechanisms function in very similar ways in two perceptual tasks and in a symbolic task. The general hypothesis and its predictions are sketched in the Introduction, after a discussion of current findings concerning visual attention and the generalities of the inferential system. In the empirical section, three experiments are presented where participants tracked visual trajectories (Experiments 1 and 3) or arithmetic series (Experiments 2 and 3), responding to the onset of a target event (e.g., to a specific number) and to the repetition of an event (e.g., to a number appearing twice consecutively). Target events could be anticipated when they were embedded in regular series/trajectories; they could be anticipated, with the anticipation later disconfirmed, when a regular series/trajectory was abruptly interrupted before the target event occurred; and they could not be anticipated when the series/trajectory was random. Repeated events could not be anticipated. Results show a very similar pattern of allocation in tracking visual trajectories and arithmetic series: Attention is focused on anticipated events; it is defocused and redistributed when an anticipation is not confirmed by ensuing events; however, performance decreases when dealing with random series/trajectory—that is, in the absence of anticipations. In our view, this is due to the fact that confirmed and disconfirmed anticipations are crucial events for “knowledge revision”—that is, the fine tuning of the inferential system to the environment; attentional mechanisms have developed so as to enhance detection of these events, possibly at all levels of inferential processing.     

Inference-driven attention in symbolic and perceptual tasks: Biases toward expected and unexpected inputs

The aims of this paper are (a) to gather support for the hypothesis that some basic mechanisms of attentional deployment (i.e., its high efficiency in dealing with expected and unexpected inputs) meet the requirements of the inferential system and have possibly evolved to support its functioning, and (b) to show that these orienting mechanisms function in very similar ways in two perceptual tasks and in a symbolic task. The general hypothesis and its predictions are sketched in the Introduction, after a discussion of current findings concerning visual attention and the generalities of the inferential system. In the empirical section, three experiments are presented where participants tracked visual trajectories (Experiments 1 and 3) or arithmetic series (Experiments 2 and 3), responding to the onset of a target event (e.g., to a specific number) and to the repetition of an event (e.g., to a number appearing twice consecutively). Target events could be anticipated when they were embedded in regular series/trajectories; they could be anticipated, with the anticipation later disconfirmed, when a regular series/trajectory was abruptly interrupted before the target event occurred; and they could not be anticipated when the series/trajectory was random. Repeated events could not be anticipated. Results show a very similar pattern of allocation in tracking visual trajectories and arithmetic series: Attention is focused on anticipated events; it is defocused and redistributed when an anticipation is not confirmed by ensuing events; however, performance decreases when dealing with random series/trajectory—that is, in the absence of anticipations. In our view, this is due to the fact that confirmed and disconfirmed anticipations are crucial events for “knowledge revision”—that is, the fine tuning of the inferential system to the environment; attentional mechanisms have developed so as to enhance detection of these events, possibly at all levels of inferential processing.     

Attentional enhancement during multiple-object tracking

What is the role of attention in multiple-object tracking? Does attention enhance target representations, suppress distractor representations, or both? It is difficult to ask this question in a purely behavioral paradigm without altering the very attentional allocation one is trying to measure. In the present study, we used event-related potentials to examine the early visual evoked responses to task-irrelevant probes without requiring an additional detection task. Subjects tracked two targets among four moving distractors and four stationary distractors. Brief probes were flashed on targets, moving distractors, stationary distractors, or empty space. We obtained a significant enhancement of the visually evoked P1 and N1 components (～100–150 msec) for probes on targets, relative to distractors. Furthermore, good trackers showed larger differences between target and distractor probes than did poor trackers. These results provide evidence of early attentional enhancement of tracked target items and also provide a novel approach to measuring attentional allocation during tracking.     

Low self-esteem and the neural basis of attentional bias for social rejection cues: Evidence from the N2pc ERP component

Previous studies have indicated that individuals with low self-esteem show an attentional bias toward information concerning social rejection. The present study used event-related potentials (ERPs) to investigate whether task-irrelevant rejection cues could capture the visuo-spatial attention of low self-esteem individuals during a demanding visual detection task. The N2pc ERP component was measured as an index of the allocation of spatial attention. Results revealed that rejection cues induced greater N2pc component responses among individuals with low levels of self-esteem than for those with high levels of self-esteem. These results suggest that task-irrelevant rejection cues are likely to capture the attention of individuals with low self-esteem but not those with high self-esteem. These findings provide direct electrophysiological support for the idea that individuals with low levels of self-esteem show an attentional bias for cues related to social rejection.     

Attentional and intentional cueing in a Simon task: An EEG-based approach

Advance information about the location of a stimulus (attentional cueing) does not affect the Simon effect (a shortening of manual response times whenever the position of a stimulus that is irrelevant for the task corresponds to the side of the response). However, advance information about the side of a response (intentional cueing) enhances the Simon effect. At first sight, these well-established results contradict two important assumptions about the origin of the Simon effect: (a) the effect originates at least in part in a covert shift of visual attention that forces the preparation of a response towards the location of the attentional shift and (b) interference between stimulus location and response side takes place within a response selection stage. We replicated the behavioral finding in a study that measured event-related potentials (ERPs) of the EEG. ERPs indicated that the mechanisms causing the Simon effect remain widely unaffected by advance information. Clear evidence for both response preparation and attentional shifts in the cue-target interval was found. Additionally, ERPs suggested that the increment of the Simon effect by intentional cueing might be due to perceptual factors rather than to an alteration in the mechanisms involved in the generation of a regular Simon effect. The implications of these data for the role of attention and of response selection in Simon tasks are discussed.     

Examining the relationships between self‐efficacy,task‐relevant attentional control,and task performance: Evidence from event‐related brain potentials

Self‐efficacy (SE) is a modifiable psychosocial factor related to individuals’ beliefs in their capabilities to successfully complete courses of action and has been shown to be positively associated with task performance. The authors hypothesized that one means through which SE is related with improved performance is through enhanced task‐relevant attentional control during task execution. To assess this hypothesis, we examined the relationships between SE and behavioural and neural indices of task performance and task‐relevant attentional control for 76 young adults during the completion of a flanker task. Results showed that greater SE was associated with greater response accuracy and P3b amplitude across task conditions, and faster RT under more difficult task conditions. Additionally, P3b amplitude was found to mediate the relationship between SE and task performance in the difficult condition. These findings suggest that greater attentional allocation to task‐relevant processes, including monitoring stimulus‐response relationships and focusing attention on working memory operations, may help explain the association between SE and improved task performance.     

Mind-reading without the scanner: Behavioural decoding of working memory content

ABSTRACT

Sophisticated machine learning algorithms have been successfully applied to functional neuroimaging data in order to characterize internal cognitive states. But is it possible to “mind-read” without the scanner? Capitalizing on the robust finding that the contents of working memory guide visual attention toward memory-matching objects, we trained a multivariate pattern classifier on behavioural indices of attentional guidance. Working memory representations were successfully decoded from behaviour alone, both within and between individuals. The current study provides a proof-of-concept for applying machine learning techniques to simple behavioural outputs (e.g., response times) in order to decode information about specific internal cognitive states.     

Event-Related Potential Correlates of Attention to Mediated Message Processing

The aim of this article is to find neural correlates of attention allocated to processing mediated messages. Event-related potentials (ERPs) for auditory distractors were recorded while subjects were engaged in watching a movie telling a short story (audio-video condition) or listening to a radio program describing the same events (audio condition). The amplitudes of the N1 and P3a components for distractors were larger in the audio than in the audio-video condition. The results indicate a stronger orienting response to auditory distractors when listening to the radio than when listening to and watching television. It confirmed predictions of the limited capacity model of motivated mediated message processing (LC4MP), which assumes that the less complex the encoded message, the more attentional resources are left for additional tasks. The largest amplitude of the P3a was observed during the first stage of encoding the message compared to the next stages. P3a amplitude to repeated auditory distractors seems to be a strong indicator of habituation. Results are discussed in the context of LC4MP and perceptual load theory of attention.     

Cognitive basis of individual differences in speech perception,production and representations: The role of domain general attentional switching

This study investigated whether individual differences in cognitive functions, attentional abilities in particular, were associated with individual differences in the quality of phonological representations, resulting in variability in speech perception and production. To do so, we took advantage of a tone merging phenomenon in Cantonese, and identified three groups of typically developed speakers who could differentiate the two rising tones (high and low rising) in both perception and production [+Per+Pro], only in perception [+Per–Pro], or in neither modalities [–Per–Pro]. Perception and production were reflected, respectively, by discrimination sensitivity d′ and acoustic measures of pitch offset and rise time differences. Components of event-related potential (ERP)—the mismatch negativity (MMN) and the ERPs to amplitude rise time—were taken to reflect the representations of the acoustic cues of tones. Components of attention and working memory in the auditory and visual modalities were assessed with published test batteries. The results show that individual differences in both perception and production are linked to how listeners encode and represent the acoustic cues (pitch contour and rise time) as reflected by ERPs. The present study has advanced our knowledge from previous work by integrating measures of perception, production, attention, and those reflecting quality of representation, to offer a comprehensive account for the underlying cognitive factors of individual differences in speech processing. Particularly, it is proposed that domain-general attentional switching affects the quality of perceptual representations of the acoustic cues, giving rise to individual differences in perception and production.     

Reward-priming impacts visual working memory maintenance: Evidence from human electrophysiology

Reward can benefit visual processing of reward-associated objects in a non-strategic way. Recent studies have suggested that such influence extends also to visual working memory (VWM) representations of reward-associated stimuli. However, it is not clear yet which mechanisms underlie the behavioural effects in VWM tasks: reward could directly impact on our ability to maintain representations in VWM or it could influence memory indirectly via priming of attentional selection. To distinguish between these alternatives we measured event-related potential indices of selective attention – the N2pc – and VWM maintenance – the CDA (contralateral delay activity) – while participants completed a VWM task. Results show that reward outcome in one trial caused similarly coloured targets to be strongly represented in VWM in subsequent trials, as expressed in a larger-amplitude CDA This was not preceded by a corresponding effect on attentional selection, in so far as our key manipulation had no impact on the N2pc. In a second experiment, we found that reward priming produced a behavioural benefit that emerged over time, suggesting that the representations of reward-associated items stored in VWM are more resistant to interference and decay. We conclude that when the task stresses VWM maintenance, it is at this representational level that reward will have impact.     

How not to be seen: the contribution of similarity and selective ignoring to sustained inattentional blindness

When people attend to objects or events in a visual display, they often fail to notice an additional, unexpected, but fully visible object or event in the same display. This phenomenon is now known as inattentional blindness . We present a new approach to the study of sustained inattentional blindness for dynamic events in order to explore the roles of similarity, distinctiveness, and attentional set in the detection of unexpected objects. In Experiment 1, we found that the similarity of an unexpected object to other objects in the display influences attentional capture: The more similar an unexpected object is to the attended items, and the greater its difference from the ignored items, the more likely it is that people will notice it. Experiment 2 explored whether this effect of similarity is driven by selective ignoring of irrelevant items or by selective focusing on attended items. The results of Experiment 3 suggest that the distinctiveness of the unexpected object alone cannot entirely account for the similarity effects found in the first two experiments; when attending to black items or white items in a dynamic display, nearly 30% of observers failed to notice a bright red cross move across the display, even though it had a unique color, luminance, shape, and motion trajectory and was visible for 5 s. Together, the results suggest that inattentional blindness for ongoing dynamic events depends both on the similarity of the unexpected object to the other objects in the display and on the observer's attentional set.     

Outcome expectancy and not accuracy determines posterror slowing: ERP support

A considerable number of studies have recently used event-related potentials (ERPs) to investigate the mechanisms underlying error processing. Nevertheless, how these mechanisms are associated with behavioral adjustments following errors remains unclear. In the present study, we investigated how posterror slowing is linked to outcome expectations and error feedback. We used an adaptive four-choice reaction time task to manipulate outcome expectancy. Behaviorally, the results show posterror slowing when errors are unexpected and postcorrect slowing when correct responses are unexpected, indicating that outcome expectancy is crucial for posterror slowing. ERP analyses revealed that the error-related negativity and the feedback-related negativity were not correlated with the behavioral reaction time pattern, whereas the P3 was. The results support the hypothesis that posterror slowing is caused by attentional orienting to unexpected events.     

Event-related brain potentials and cognitive processes related to perceptual—motor information transmission

In the present study, event-related potentials (ERPs) were recorded to investigate cognitive processes related to the partial transmission of information from stimulus recognition to response preparation. Participants classified two-dimensional visual stimuli with dimensions size and form. One feature combination was designated as the go-target, whereas the other three feature combinations served as no-go distractors. Size discriminability was manipulated across three experimental conditions. N2c and P3a amplitudes were enhanced in response to those distractors that shared the feature from the faster dimension with the target. Moreover, N2c and P3a amplitudes showed a crossover effect: Size distractors evoked more pronounced ERPs under high size discriminability, but form distractors elicited enhanced ERPs under low size discriminability. These results suggest that partial perceptual—motor transmission of information is accompanied by acts of cognitive control and by shifts of attention between the sources of conflicting information. Selection negativity findings imply adaptive allocation of visual feature-based attention across the two stimulus dimensions.     

Attention-Deficit Hyperactivity Disorder and Event-Related Potentials: Evidence for Deficits in Allocating Attentional Resources to Relevant Stimuli

Current research on the nature of attentional deficits in attention-deficit hyperactivity disorder (ADHD) is reviewed with a focus on studies using event-related potentials (ERPs). A robust effect is the smaller amplitude of the P3 wave to both auditory and visual stimuli for individuals with ADHD than for normal controls. This effect is indicative of deficits in the allocation of attentional resources to task-relevant information. The Nd wave is also smaller for individuals with ADHD, an effect that suggests impairments in the discrimination and preferential processing of task-relevant information, rather than distractibility by irrelevant stimuli. Studies of the effects of methylphenidate on ERPs in ADHD indicate that this stimulant enhances the quality of stimulus evaluation and speeds response time. These specific effects support the view that ADHD involves deficits in energetic processes that are required for processing task-relevant stimuli.     

Division of attention: Age differences on a visually presented memory task

Young and old adults were compared in their efficiency of remembering concurrently presented series of letters and digits in three separate experiments. Instructions and payoffs to vary attentional emphasis across the two types of material in different conditions allowed the examination of attention-operating characteristics in the two age groups. Strategy-independent measures derived from these attention-operating characteristics revealed that older adults exhibited greater performance deficits than young adults when dividing their attention between the two tasks, even though dual-task difficulty was individually adjusted for each subject. It was concluded that either the total amount of attention available for distribution or the efficiency of its allocation decreased with age even though the ability to vary one’s attention between concurrent tasks in response to instructions and payoffs remained intact.