Cue-target Interval Research Articles

Incorrect predictions reduce switch costs

In three experiments, we combined two sources of conflict within a modified task-switching procedure. The first source of conflict was the one inherent in any task switching situation, namely the conflict between a task set activated by the recent performance of another task and the task set needed to perform the actually relevant task. The second source of conflict was induced by requiring participants to guess aspects of the upcoming task (Exps. 1 & 2: task identity; Exp. 3: position of task precue). In case of an incorrect guess, a conflict accrues between the representation of the guessed task and the actually relevant task. In Experiments 1 and 2, incorrect guesses led to an overall increase of reaction times and error rates, but they reduced task switch costs compared to conditions in which participants predicted the correct task. In Experiment 3, incorrect guesses resulted in faster performance overall and to a selective decrease of reaction times in task switch trials when the cue-target interval was long. We interpret these findings in terms of an enhanced level of controlled processing induced by a combination of two sources of conflict converging upon the same target of cognitive control.

Fixation instruction influences gaze cueing

Studies have shown that perceiving another person's gaze shift facilitates responses in the direction of the perceived gaze shift. While it is often assumed that participants in these experiments remain fixated on the cue in the cueing interval, eye gaze is not always recorded to confirm this. The data presented here suggest that the effect of gaze cues on responses to peripheral targets depends on whether participants make eye movements prior to the onset of the target. Participants who were required to fixate showed cueing effects at short cue-target intervals, but no cueing at later intervals. Participants who could look around, often chose to do so, and showed the same positive cueing effects at the shorter interval, but negative cueing effects (suggestive of inhibition of return) at the longer interval.

Children can implicitly, but not voluntarily, direct attention in time.

Children are able to use spatial cues to orient their attention to discrete locations in space from around 4 years of age. In contrast, no research has yet investigated the ability of children to use informative cues to voluntarily predict when an event will occur in time. The spatial and temporal attention task was used to determine whether children were able to voluntarily orient their attention in time, as well as in space: symbolic spatial and temporal cues predicted where or when an imperative target would appear. Thirty typically developing children (average age 11 yrs) and 32 adults (average age 27 yrs) took part. Confirming previous findings, adults made use of both spatial and temporal cues to optimise behaviour, and were significantly slower to respond to invalidly cued targets in either space or time. Children were also significantly slowed by invalid spatial cues, demonstrating their use of spatial cues to guide expectations. In contrast, children’s responses were not slowed by invalid temporal cues, suggesting that they were not using the temporal cue to voluntarily orient attention through time. Children, as well as adults, did however demonstrate signs of more implicit forms of temporal expectation: RTs were faster for long versus short cue-target intervals (the variable foreperiod effect) and slower when the preceding trial’s cue-target interval was longer than that on the current trial (sequential effects). Overall, our results suggest that although children implicitly made use of the temporally predictive information carried by the length of the current and previous trial’s cue-target interval, they could not deliberately use symbolic temporal cues to speed responses. The developmental trajectory of the ability to voluntarily use symbolic temporal cues is therefore delayed, relative both to the use of symbolic (arrow) spatial cues, and to the use of implicit temporal information.

The attentional 'zoom-lens' in 8-month-old infants.

The spatial attention mechanisms of orienting and zooming cooperate to properly select visual information from the environment and plan eye movements accordingly. Despite the fact that orienting ability has been extensively studied in infancy, the zooming mechanism--namely, the ability to distribute the attentional resources to a small or large portion of the visual field--has never been tested before. The aim of the present study was to evaluate the attentional zooming abilities of 8-month-old infants. An eye-tracker device was employed to measure the saccadic latencies (SLs) at the onset of a visual target displayed at two eccentricities. The size of the more eccentric target was adjusted in order to counteract the effect of cortical magnification. Before the target display, attentional resources were automatically focused (zoom-in) or spread out (zoom-out) by using a small or large cue, respectively. Two different cue-target intervals were also employed to measure the time course of this attentional mechanism. The results showed that infants' SLs varied as a function of the cue size. Moreover, a clear time course emerged, demonstrating that infants can rapidly adjust the attentional focus size during a pre-saccadic temporal window. These findings could serve as an early marker for neurodevelopmental disorders associated with attentional zooming dysfunction such as autism and dyslexia.

S-ketamine influences strategic allocation of attention but not exogenous capture of attention.

We investigated whether s-ketamine differentially affects strategic allocation of attention. In Experiment 1, (1) a less visible cue was weakly masked by the onsets of competing placeholders or (2) a better visible cue was not masked because it was presented in isolation. Both types of cue appeared more often opposite of the target (75%) than at target position (25%). With this setup, we tested for strategic attention shifts to the opposite side of the cues and for exogenous attentional capture toward the cue's side in a short cue-target interval, as well as for (reverse) cueing effects in a long cue-target interval after s-ketamine and after placebo treatment in a double-blind within-participant design. We found reduced strategic attention shifts after cues presented without placeholders for the s-ketamine compared to the placebo treatment in the short interval, indicating an early effect on the strategic allocation of attention. No differences between the two treatments were found for exogenous attentional capture by less visible cues, suggesting that s-ketamine does not affect exogenous attentional capture in the presence of competing distractors. Experiment 2 confirmed that the competing onsets of the placeholders prevented the strategic cueing effect. Taken together, the results indicate that s-ketamine affects strategic attentional capture, but not exogenous attentional capture. The findings point to a more prominent role of s-ketamine during top-down controlled forms of attention that require suppression of automatic capture than during automatic capture itself.

Inhibition of return is not impaired but masked by increased facilitation in schizophrenia patients.

When attention is attracted to an irrelevant location, performance on a subsequent target is hindered at that location in relation to novel, not previously attended, locations. This phenomenon is known as inhibition of return (IOR). Previous research has shown that IOR is not observed, or its onset is delayed, in schizophrenia patients. In the present study, the authors tested the hypothesis that IOR may be intact but masked by increased facilitation in schizophrenia patients. To test this hypothesis, they used a procedure that usually reduces or eliminates the early facilitation. In the first experiment, the authors used the typical single-cue IOR task in the group of healthy adults (N = 28) and in a group of schizophrenia patients (N = 32). In the second experiment, they manipulated cue-target discriminability by presenting spatially overlapping cues and targets where the cues were more intense than the targets. In Experiment 1, they did not find significant IOR effects in the group of schizophrenia patients, even with cue-target intervals as long as 3,200 ms. However, in Experiment 2, IOR effects were significant at the 350- and 450-ms cue-target intervals for healthy and patients, respectively. This is the first study that shows that schizophrenia patients can actually show inhibitory effects very similar to healthy controls, even when no help is provided to shift their attention away from the irrelevant location. The authors suggest that inhibition is intact in schizophrenia patients, but it is usually masked by increased facilitation.

Microsaccade-related brain potentials signal the focus of visuospatial attention

Covert shifts of visuospatial attention are traditionally assumed to occur in the absence of oculomotor behavior. In contrast, recent behavioral studies have linked attentional cueing effects to the occurrence of microsaccades, small eye movements executed involuntarily during attempted fixation. Here we used a new type of electrophysiological marker to explore the attention–microsaccade relationship, the visual brain activity evoked by the microsaccade itself. By shifting the retinal image, microsaccades frequently elicit neural responses throughout the visual pathway, scalp-recordable in the human EEG as a microsaccade-related potential (mSRP). Although mSRPs contain similar signal components (P1/N1) as traditional visually-evoked potentials (VEPs), it is unknown whether they are also influenced by cognition. Based on established findings that VEPs are amplified for visual inputs at currently attended locations, we expected a selective gain-modulation also for mSRPs. Eye movements and EEG were coregistered in a classic spatial cueing task with an endogenous cue. Replicating behavioral findings, the direction of early microsaccades 200–400ms after cue onset was biased towards the cued side. However, for microsaccades throughout the cue-target interval, mSRPs were systematically enhanced at occipital scalp sites contralateral to the cued hemifield. This attention effect resembled that in a control condition with VEPs and did not interact with the direction of the underlying microsaccade, suggesting that mSRPs reflect the focus of sustained visuospatial attention, which remains fixed at the cued location, despite microsaccades. Microsaccades are not merely an artifact source in the EEG; instead, they are followed by cognitively modulated brain potentials that can serve as non-intrusive electrophysiological probes of attention.

Inhibition of Return, but Not Facilitation, Disappears Under Vigilance Decrease Due to Sleep Deprivation

In this study, we assessed whether unspecific attention processes signaled by general reaction times (RTs), as well as specific facilitatory (validity or facilitation effect) and inhibitory (inhibition of return, IOR) effects involved in the attentional orienting network, are affected by low vigilance due to both circadian factors and sleep deprivation (SD). Eighteen male participants performed a cuing task in which peripheral cues were nonpredictive about the target location and the cue-target interval varied at three levels: 200 ms, 800 ms, and 1,100 ms. Facilitation with the shortest and IOR with the longest cue-target intervals were observed in the baseline session, thus replicating previous related studies. Under SD condition, RTs were generally slower, indicating a reduction in the participants' arousal level. The inclusion of a phasic alerting tone in several trials partially compensated for the reduction in tonic alertness, but not with the longest cue-target interval. With regard to orienting, whereas the facilitation effect due to reflexive shifts of attention was preserved with sleep loss, the IOR was not observed. These results suggest that the decrease of vigilance produced by SD affects both the compensatory effects of phasic alerting and the endogenous component involved in disengaging attention from the cued location, a requisite for the IOR effect being observed.

Disgust-specific modulation of early attention processes

Although threatening images are known to attract and keep our attention, little is known about the existence of emotion-specific attention effects. In this study (N=46), characteristics of an anticipated, disgust-specific effect were investigated by means of a covert orienting paradigm incorporating pictures that were either disgust-evoking, fear-evoking, happiness-evoking or neutral. Attention adhesion to these pictures was measured by the time necessary to identify a peripheral target, presented 100, 200, 500, or 800ms after picture onset. Main results showed that reaction times were delayed for targets following the disgust-evoking pictures by 100 and 200ms, suggesting that only these pictures temporarily grabbed hold of participants' attention. These delays were similar for ignore- and attend-instructions, and they were not affected by the participants' anxiety levels or disgust sensitivity. The disgust-specific influence on early attention processes thus appeared very robust, occurring in the majority of participants and without contribution of voluntary- and strategic-attention processes. In contrast, a smaller and less reliable effect of all emotional (arousing) pictures was present in the form of delayed responding in the 100ms cue-target interval. This effect was more transitory and apparent only in participants with relatively high state-anxiety scores. Practical and theoretical consequences of these findings are discussed.

Removal of information from working memory: A specific updating process

Abstract Previous research has claimed that working memory (WM) updating is one of three primary central executive processes, and the only one to reliably predict fluid intelligence. However, standard WM updating tasks confound updating requirements with generic WM functions. This article introduces a method for isolating a process unique to WM updating, namely the removal of no-longer relevant information. In a modified version of an established updating paradigm, to-be-updated items were cued before the new memoranda were presented. Overall, longer cue-target intervals—that is, longer time available for removal of outdated information—led to faster updating, suggesting that people can actively remove information from WM. Experiments 1 and 2 demonstrated that well-established effects of item repetition and similarity on updating RTs were diminished with longer cue-target interval, arguably because representational overlap between outdated and new information becomes less influential when outdated information can be removed prior to new encoding. Experiment 3 looked at individual differences, using the reduction of updating RTs to measure removal speed. Removal speed was measured reliably but was uncorrelated to WM capacity. We conclude that (1) removal of outdated information can be experimentally isolated and measured reliably, (2) removal speed is a unique, active WM updating ability, and (3) the view of WM updating as a core executive process that uniquely predicts fluid abilities is overstated.

Attentional dynamics mediated by subcortical mechanisms.

Following a salient cue that attracts attention to a specific spatial location, perceptual processing of information at that location is facilitated if the interval between the cue and target is brief, or, is inhibited if the interval between the cue and target is long. The mechanisms mediating these attentional dynamics continue to be the subject on ongoing debate. On one classic account, facilitation and inhibition of return (IOR) are two ends of a continuum, generated by the same underlying mechanism. Other accounts have postulated that these two attentional processes emerge from independent systems. To address these alternatives, we report data from three experiments in which a cue and its ensuing target are presented to the same or different eyes at varying cue-target intervals. Whereas the onset of facilitation was apparent earlier when the cue and target shared the eye-of-origin, the onset of IOR was not affected by the eye to which the cue and target were presented. This finding implicates at least some, if not full, independence in the system(s) that give rise to attentional facilitation and IOR, and, moreover, suggests that facilitation may be more reliant on subcortical levels of the visual pathways than IOR.

ERPs dissociate proactive and reactive control: evidence from a task-switching paradigm with informative and uninformative cues.

According to the dual mechanism of control (DMC) framework, cognitive control can be recruited proactively to prevent response conflict when advance preparation is feasible or is up-regulated to overcome response conflict after it is detected. This study aimed at empirically dissociating proactive and reactive control processes proposed by the DMC and identifying corresponding event-related potential (ERP) correlates. Behavioral and electrophysiological indices of cognitive control were measured during a task-switch paradigm with or without informative advance cues, in which proactive control was feasible or not. Proactive control was associated with a (right-) frontal sustained ERP modulation during the cue-target interval. In line with the successful recruitment of proactive control, informative, as compared with uninformative, cue conditions were associated with reduced behavioral and ERP correlates of conflict. ERP correlates of conflict were evident both during conflict detection upon target presentation (N(inc)) and during conflict resolution-in particular, following uninformative cues. Reactive control assumed to support conflict resolution was associated with a (left-) frontal transient preresponse ERP modulation for uninformative, but not informative, cue conditions. Together, these data suggest that complementary proactive and reactive control processes operate in concert to flexibly support goal-directed behavior in response to variable task-demands, by either preventing or resolving response conflicts, as they are detected or anticipated.

On the role of the ventral attention system in spatial orienting

On the role of the ventral attention system in spatial orienting

Modulation of Response to Audiovisual Stimuli Presented Peripherally by Visually Cued Endogenous Temporal Attention: An Event-Related Potentials Study

Previous studies have used the cue-target paradigm to study the effect of the endogenous temporal attention on only visual or auditory stimuli. Furthermore, some studies found that the visual and auditory stimuli is not processed in isolation but produce coherent cognition in the brain when the visual and auditory stimuli are simultaneously presented. However, the effect of endogenous temporal attention on audiovisual (AV) stimuli processing is unclear. Utilizing the high temporal resolution of event-related potentials (ERPs), we used a central cue that can predict the time point (600 ms or 1800 ms) of audiovisual target to investigate whether endogenous temporal attention could modulate AV stimuli processing. The results showed that the endogenous temporal attention could not change the amplitude of the early ERP component in conditions of either short (600 ms) or long (1800 ms) cue-target intervals, indicating that the endogenous temporal attention had no effect on the early-stage of AV stimuli processing. However, the late ERP component showed differences between the short (600 ms) and long (1800 ms) cue-target intervals, supporting a model in which endogenous temporal attention might determine the late stage of AV stimuli processing. Keywords: Audiovisual stimuli, endogenous temporal attention, event-related potentials (ERPs), interstimulus interval (ISI).

Cue type affects preparatory influences on task inhibition

The present study investigates the influence of preparation on inhibitory effects in cued task switching. In three experiments, we assessed n−2 repetition costs as marker of inhibition of the just executed and now irrelevant task by comparing performance in task sequences such as ABA (i.e., n−2 repetitions, with A, B and C standing for different tasks) to task sequences such as CBA (i.e., n−2 switches). Specifically, we varied the cue–target interval (CTI) to examine cue-based preparation effects. In addition, we manipulated cue type (i.e., abstract, verbal, and direct cues) across the three experiments. We obtained significant reductions of n−2 repetition costs with prolonged CTI when using abstract cues (i.e., coloured frames) and task names (i.e., digit), but not when using the task-specific stimulus–response mapping as cue for the upcoming task. These data suggest that cue-based preparation is not a uniform process but depends on the information provided by the cue.

N − 2 repetition costs depend on preparation in trials n − 1 and n − 2.

In task switching, a common result supporting the notion of inhibitory processes as a determinant of switch costs is the occurrence of n - 2 repetition costs. Evidence suggests that this effect is not affected by preparation. However, the role of preparation on preceding trials has been neglected so far. In this study, evidence for an influence of preparatory processes on n - 2 repetition costs is provided by focusing on the cue-target interval on trials n - 1 and n - 2. N - 2 repetition costs were affected by an interaction of both n - 1 and n - 2 preparation time, being more pronounced when both preparatory intervals were long. The results provide support for the notion of active preparation processes involved in backward inhibition.

Which way is which? Examining global/local processing with symbolic cues.

A new method combining spatial-cueing and compound-stimulus paradigms draws on involuntary attentional orienting elicited by a spatially uninformative central arrow cue to investigate global/local processing under incidental processing conditions, wherein global/local levels were uninformative (do not aid performance) and task-irrelevant (need not be processed to perform the task). The task was peripheral target detection. Cues were compound arrows, which were either consistent (global/local arrows oriented in same direction) or inconsistent (global/local arrows oriented in opposite directions). Global/local processing was measured by spatial-cueing effects (response time [RT] difference between target locations validly cued by an arrow and targets at different locations), with the test of global/local advantage represented by the effect of cue-level for inconsistent cues (RT difference between global-valid and local-valid cues). Cue-target interval (stimulus-onset-asynchrony [SOA]) was manipulated to test whether global/local advantage varied with relative stimulus availability. Experiment 1 observed a Cue-Level × SOA interaction such that an early, large global cueing effect was followed by a later, smaller local cueing effect, indicative of a global-to-local shift in advantage. This occurred despite knowledge that global/local arrows were uninformative and task-irrelevant and could therefore be ignored, thus displaying key properties of an involuntary process. Experiment 2 added neutral cues (arrow at one level, rectangle at the other) and determined that the reversal was not due to inhibition of the globally cued location or to attenuation of global information but rather to the presence of conflicting spatial information. Experiments 3 and 4 ruled out alternative accounts for these results. These data indicate global precedence in attended but incidentally processed objects.

Task-Related Changes in Functional Properties of the Human Brain Network Underlying Attentional Control

Previous studies have demonstrated task-related changes in brain activation and inter-regional connectivity but the temporal dynamics of functional properties of the brain during task execution is still unclear. In the present study, we investigated task-related changes in functional properties of the human brain network by applying graph-theoretical analysis to magnetoencephalography (MEG). Subjects performed a cue-target attention task in which a visual cue informed them of the direction of focus for incoming auditory or tactile target stimuli, but not the sensory modality. We analyzed the MEG signal in the cue-target interval to examine network properties during attentional control. Cluster-based non-parametric permutation tests with the Monte-Carlo method showed that in the cue-target interval, beta activity was desynchronized in the sensori-motor region including premotor and posterior parietal regions in the hemisphere contralateral to the attended side. Graph-theoretical analysis revealed that, in beta frequency, global hubs were found around the sensori-motor and prefrontal regions, and functional segregation over the entire network was decreased during attentional control compared to the baseline. Thus, network measures revealed task-related temporal changes in functional properties of the human brain network, leading to the understanding of how the brain dynamically responds to task execution as a network.

Effects of relevant and irrelevant color singletons on inhibition of return and attentional capture

We tested whether color singletons lead to saccadic and manual inhibition of return (IOR; i.e., slower responses at cued locations) and whether IOR depended on the relevance of the color singletons. The target display was preceded by a nonpredictive cue display. In three experiments, half of the cues were response-relevant, because participants had to perform a discrimination task at the cued location. With the exception of Experiment 2, none of the cue colors matched the target color. We observed saccadic IOR after color singletons, which was greater for slow than for fast responses. Furthermore, when the relevant cue color matched the target color, we observed attentional capture (i.e., faster responses at cued locations) with rapid responses, but IOR with slower responses, which provides evidence for attentional deallocation. When the cue display was completely response-irrelevant in two additional experiments, we did not find evidence for IOR. Instead, we found attentional capture when the cue color matched the target color. Also, attentional capture was greater for rapid responses and with short cue-target intervals. Thus, IOR emerges when cues are relevant and do not match the target color, whereas attentional capture emerges with relevant and irrelevant cues that match the target color.

P 54. Top-down control of posterior alpha oscillations by the frontal eye field: An fMRI-guided TMS-MEG study

Alpha oscillations in visual cortex serve as a mechanism of attentional enhancement via inhibition of task-irrelevant brain regions (Jensen et al., TICS 2012). Humans are able to direct their attention to one visual hemifield in response to an endogenous cue via the modulation of alpha power in visual areas. This top-down control of spatial attention might be mediated by the frontal eye fields (FEF), a key part of the dorsal fronto-parietal attention network. Importantly, previous research has suggested a right-hemispheric dominance of this network: Damage to right frontal and parietal cortex is a predictor of spatial hemineglect (Thiebaut de Schotten et al., Cereb Cortex 2012) and Transcranial Magnetic Stimulation (TMS) of right FEF has been shown to have perceptual consequences for both hemifields, while left FEF TMS affects only the contralateral hemifield (Grosbras and Paus, EJN 2003). Evaluate the differential role of right and left FEF as sources of top-down control of visuospatial attention via the modulation of posterior alpha power in the ipsi-and/or contralateral visual cortex. Fifteen participants (preliminary dataset) received continuous theta burst stimulation (cTBS) to either left FEF, right FEF or scalp vertex (control) before performing an endogenously cued visual spatial attention task whilst magnetoencephalography (MEG) data were recorded. cTBS is known to inhibit activity in FEF for 30–35 min (Nyffeler et al., Neurosci Lett 2006). Individual FEF target sites were identified using an fMRI-based functional localizer. Preliminary MEG analysis focused on the attentional modulation of posterior alpha power during the cue-target interval. After vertex cTBS, we observed the typical pattern of alpha power decreases contralateral and increases ipsilateral to the target hemifield (Thut et al., J Neurosci 2006, Gould et al., JCN 2011). However, following cTBS to both right and left FEF this modulation appeared to be attenuated, with stronger effects observable in the left hemisphere following right FEF cTBS. We are currently investigating the relation between cTBS-induced changes in posterior alpha power modulation and the participants’ behavioural performance. Functional connectivity measures will be employed to determine cTBS-induced changes in long-range coupling between frontal and visual cortex. cTBS to both right and left FEF causes attenuation of cue-related modulation of posterior alpha oscillations with a stronger effect caused by right FEF cTBS.