Cue-target Onset Asynchrony Research Articles

Spatial prediction modulates the rhythm of attentional sampling.

Recent studies demonstrate that behavioral performance during visual spatial attention fluctuates at theta (4 to 8Hz) and alpha (8 to 16Hz) frequencies, linked to phase-amplitude coupling of neural oscillations within the visual and attentional system depending on task demands. To investigate the influence of prior spatial prediction, we employed an adaptive discrimination task with variable cue-target onset asynchronies (300 to 1,300ms) and different cue validity (100% & 50%). We recorded electroencephalography concurrently and adopted adaptive electroencephalography data analytical methods, namely, Holo-Holo-Hilbert spectral analysis and Holo-Hilbert cross-frequency phase clustering. Our findings indicate that response precision for near-threshold Landolt rings fluctuates at the theta band (4Hz) under certain predictions and at alpha & beta bands (15 & 19Hz) with uncertain predictions. Furthermore, spatial prediction strengthens theta-alpha modulations at parietal-occipital areas, frontal theta/parietal-occipital alpha phase-amplitude coupling, and within frontal theta-alpha phase-amplitude coupling. Notably, during the pretarget period, beta-modulated gamma oscillations in parietal-occipital areas predict response precision under uncertain prediction, while frontal theta/parietal-occipital alpha phase-amplitude coupling predicts response precision in spatially certain conditions. In conclusion, our study highlights the critical role of spatial prediction in attentional sampling rhythms with both behavioral and electroencephalography evidence.

No evidence for rhythmic sampling in inhibition of return.

When exogenously cued, attention reflexively reorients towards the cued position. After a brief dwelling time, attention is released and then persistently inhibited from returning to this position for up to three seconds, a phenomenon coined 'inhibition of return' (IOR). This inhibitory interpretation has shaped our understanding of the spatio-temporal dynamics of the attentional spotlight after an exogenous visual cue for more than three decades. However, a recent theory refines this traditional view and predicts that attention rhythmically alternates between possible target locations at a theta frequency, implying occasional returns of attention to the cued position. Unfortunately, previous IOR studies have only probed performance at a few, temporally wide-spread cue-target onset asynchronies (CTOAs) rendering a comparison of these contradictory predictions impossible. We therefore used a temporally fine-grained adaptation of the Posner paradigm with 25 equally and densely spaced CTOAs, which yielded a robust IOR effect in the reaction time difference between valid and invalidly cued trials. We modelled the time course of this effect across CTOAs as a linear or exponential decay (traditional IOR model), sinusoidal rhythm (rhythmic model) and a combination of both (hybrid model). Model comparison by means of goodness-of-fit indices provided strong evidence in favor of traditional IOR models, and against theta-rhythmic attentional sampling contributing to IOR. This finding was supported by an FFT analysis, which also revealed no significant theta rhythm. We therefore conclude that the spatio-temporal dynamics of attention following an exogenous cue cannot be explained by rhythmic attentional sampling.

Different gain modulations of selective attention at short and long cue-target delays.

Previous studies have tested attentional gain patterns, for example, within the normalization model of attention (NMoA), by altering the relative sizes of the attention field and stimuli. Existing studies have not investigated whether the gain patterns of altering the relative exogenous cue size as compared with the target stimuli matches the prediction of NMoA and whether these gain patterns exist in the late stage of attentional processing. To resolve these questions, the present study maintained the target grating size and changed the exogenous cue size in both short and long cue-target onset asynchronies (CTOAs) conditions. The results revealed response gain for small cue/large target size conditions and contrast gain for large cue/small target size conditions, which was consistent with the NMoA. However, we observed the decrease in the contrast gain factor only with long CTOAs, regardless of whether the cue size was relatively small or large. This indicated that NMoA-related effects based on the relative attentional field dominated in the early stage and that the contrast gain dominated in the late stage.

The superior response speed of table tennis players is associated with proactive inhibitory control.

ObjectiveTo explore the mechanism behind the faster volitional reaction time (RT) of open skill sports athletes from the perspective of proactive inhibitory control, with the hypothesis that the superior response speed of athletes from open skill sports is related to their enhanced capacity for releasing inhibition.MethodsParticipants were divided into two groups, an experimental group of 27 table tennis players and a control group of 27 non-athletes. By manipulating cue–target onset asynchrony (CTOA) in a simple cue-target detection task, the timing of target presentation occurred in different phases of the disinhibition process. The time needed for disinhibition were compared between groups.ResultsFor the experimental group, RT varied with CTOA at delays less than 200 ms; for CTOAs greater than 200 ms, RTs were not significantly different. For the control group, RT varied with CTOA for delays as long as 300 ms.ConclusionsTable tennis players took less time (200 ms) than non-athletes (300 ms) to complete the disinhibition process, which might partly explain their rapid response speed measured in unpredictable contexts.SignificanceThe study provided evidence for disinhibition speed as a new index to assess the capacity of proactive inhibitory control, and provided a new perspective to explore the superior RT of athletes from open skill sports. We also offered support for the fundamental cognitive benefits of table tennis training.

Cue-target onset asynchrony modulates interaction between exogenous attention and audiovisual integration.

Previous studies have shown that exogenous attention decreases audiovisual integration (AVI); however, whether the interaction between exogenous attention and AVI is influenced by cue-target onset asynchrony (CTOA) remains unclear. To clarify this matter, twenty participants were recruited to perform an auditory/visual discrimination task, and they were instructed to respond to the target stimuli as rapidly and accurately as possible. The analysis of the mean response times showed an effective cueing effect under all cued conditions and significant response facilitation for all audiovisual stimuli. A further comparison of the differences between the probability of audiovisual cumulative distributive functions (CDFs) and race model CDFs showed that the AVI latency was shortened under the cued condition relative to that under the no-cue condition, and there was a significant break point when the CTOA was 200ms, with a decrease in the AVI upon going from 100 to 200ms and an increase upon going from 200 to 400ms. These results indicated different mechanisms for the interaction between exogenous attention and the AVI under the shorter and longer CTOA conditions and further suggested that there may be a temporal window in which the AVI effect is mainly affected by exogenous attention, but the interaction might be interfered with by endogenous attention when exceeding the temporal window.

On the putative role of intervening events in exogenous attention.

In exogenous attention, two main behavioural effects are usually observed across time: facilitation at short cue-target onset asynchronies (CTOAs), and Inhibition of Return (IOR) at longer CTOAs. The presentation of an intervening event (IE)-i.e., a cue presented at fixation between the peripheral cue and target period-favours the appearance of IOR. However, although there is a general consensus on this empirical modulation, there is no agreement about the putative role of IEs and/or the mechanism/s underlying their effect. While some authors consider IEs as a "cue-back", automatically reorienting attention to fixation, thus allowing IOR to occur, others have considered IEs as events modulating cue-target integration processes, consequently affecting exogenous cueing. Even in this later case, it is not clear whether IEs modulate cueing by inducing an attentional set (top-down) modulation or by inducing a trial-by-trial (bottom-up) online modulation. To disentangle this issue, in two experiments, we manipulated the proportion of trials in which the IE was presented, thus being able to measure the effect of the presence/absence and proportion of IEs. We observed a gradual influence of the % of IEs over cueing effects, which becomes less positive or more negative as the % of IEs increases. This pattern of findings fits well with the idea that facilitation and IOR depend on cue-target integration processes, and presents critical implications for the open debate about the mechanism/s underlying exogenous spatial cueing effects.

Inhibitory and Facilitatory Cueing Effects: Competition between Exogenous and Endogenous Mechanisms.

Inhibition of return is characterized by delayed responses to previously attended locations when the cue-target onset asynchrony (CTOA) is long enough. However, when cues are predictive of a target’s location, faster reaction times to cued as compared to uncued targets are normally observed. In this series of experiments investigating saccadic reaction times, we manipulated the cue predictability to 25% (counterpredictive), 50% (nonpredictive), and 75% (predictive) to investigate the interaction between predictive endogenous facilitatory (FCEs) and inhibitory cueing effects (ICEs). Overall, larger ICEs were seen in the counterpredictive condition than in the nonpredictive condition, and no ICE was found in the predictive condition. Based on the hypothesized additivity of FCEs and ICEs, we reasoned that the null ICEs observed in the predictive condition are the result of two opposing mechanisms balancing each other out, and the large ICEs observed with counterpredictive cueing can be attributed to the combination of endogenous facilitation at uncued locations with inhibition at cued locations. Our findings suggest that the endogenous activity contributed by cue predictability can reduce the overall inhibition observed when the mechanisms occur at the same location, or enhance behavioral inhibition when the mechanisms occur at opposite locations.

Children With Mathematical Learning Difficulties Are Sluggish in Disengaging Attention.

Mathematical learning difficulties (MLD) refer to a variety of deficits in math skills, typically pertaining to the domains of arithmetic and problem solving. The present study examined the time course of attentional orienting in MLD children with a spatial cueing task, by parametrically manipulating the cue-target onset asynchrony (CTOA). The results of Experiment 1 revealed that, in contrast to typical developing children, the inhibitory aftereffect of attentional orienting – frequently referred to as inhibition of return (IOR) – was not observed in the MLD children, even at the longest CTOA tested (800 ms). However, robust early facilitation effects were observed in the MLD children, suggesting that they have difficulties in attentional disengagement rather than attentional engagement. In a second experiment, a secondary cue was introduced to the cueing task to encourage attentional disengagement and IOR effects were observed in the MLD children. Taken together, the present experiments indicate that MLD children are sluggish in disengaging spatial attention.

Dyslexic children are sluggish in disengaging spatial attention

Previous work has shown that inefficient attentional orienting is likely a causal factor for dyslexia; however, the nature of this attentional dysfunction remains unclear. The process of attentional orienting is characterized by an early facilitation effect, resulting from the successful engagement of attention, and a later inhibitory effect-frequently referred to as inhibition of return (IOR)-which encourages attentional disengagement and facilitates efficient visual sampling. The present study examined the time course of attentional orienting in dyslexic and typically developing children, by parametrically manipulating the cue-target onset asynchronies in a spatial cueing task. Experiment 1 revealed an early facilitation effect in dyslexic children, suggesting that they have no issue in engaging attention to salient spatial locations. However, contrast to both age-matched and reading level-matched healthy controls, no reliable IOR effect was observed in dyslexic children, suggesting that they have difficulties in disengaging attention. When a second cue was presented to encourage attentional disengagement in Experiment 2, reliable IOR effects were observed in the same group of dyslexic children, and importantly, the onset time of IOR was comparable with that in healthy controls. These results clearly show a selective impairment of attentional disengagement in dyslexic children and provide a solid empirical basis for intervention programmes focusing on attentional shifting.

Using Rescorla's truly random control condition to measure truly exogenous covert orienting.

Studies of exogenous covert orienting use peripheral cues (stimuli) that are spatially uninformative about the locations of subsequent targets. When the time course of the cue's influence on performance is explored (by varying the cue target onset asynchrony; CTOA), a biphasic pattern is usually seen with better performance at the cued location when the CTOA is short (typically attributed to attentional capture) and worse performance at the cued location when the CTOA is long (attributed to inhibition of return). However, while spatially uninformative, these cues (even when a nonaging foreperiod is used) entail a temporal contingency with the subsequent target. Consequently, this so-called capture may reflect an unintended consequence of endogenous allocation of temporal attention. Following Lawrence and Klein (Journal of Experimental Psychology: General, 142(2), 560-572, 2013) we used Rescorla's (Psychological Review, 74, 71-80, 1967) truly random control condition to ensure that the spatially uninformative peripheral stimuli were temporally completely uninformative. Even such completely uninformative peripheral stimuli generated the prototypical biphasic pattern.

Phasic alertness cues modulate visual processing speed in healthy aging.

Warning signals temporarily increase the rate of visual information in younger participants and thus optimize perception in critical situations. It is unclear whether such important preparatory processes are preserved in healthy aging. We parametrically assessed the effects of auditory alertness cues on visual processing speed and their time course using a whole report paradigm based on the computational Theory of Visual Attention. We replicated prior findings of significant alerting benefits in younger adults. In conditions with short cue-target onset asynchronies, this effect was baseline-dependent. As younger participants with high baseline speed did not show a profit, an inverted U-shaped function of phasic alerting and visual processing speed was implied. Older adults also showed a significant cue-induced benefit. Bayesian analyses indicated that the cueing benefit on visual processing speed was comparably strong across age groups. Our results indicate that in aging individuals, comparable to younger ones, perception is active and increased expectancy of the appearance of a relevant stimulus can increase the rate of visual information uptake.

Sensory adaptation and inhibition of return: dissociating multiple inhibitory cueing effects.

Inhibition of return (IOR) refers to an increase in reaction times to targets that appeared at a previously cued location relative to an uncued location, often investigated using a spatial cueing paradigm. Despite numerous studies that have examined many aspects of IOR, the neurophysiological mechanisms underlying IOR are still in dispute. The objective of the current research is to investigate the plausible mechanisms by manipulating the cue and target types between central and peripheral stimuli in a traditional cue-target paradigm with saccadic responses to targets. In peripheral-cueing conditions, we observed inhibitory cueing effects across all cue-target onset asynchronies (CTOAs) with peripheral targets, but IOR was smaller and arose later with central targets. No inhibition was observed in central-cueing conditions at any CTOAs. Empirical data were simulated using a two-dimensional dynamic neural field model. Our results and simulations support previous work demonstrating that, at short CTOAs, behavioral inhibition is only observed with repeated stimulation-an effect of sensory adaptation. With longer CTOAs, IOR is observed regardless of target type when peripheral cueing is used. Our findings suggest that behaviorally exhibited inhibitory cueing effects can be attributed to multiple mechanisms, including both attenuation of visual stimulation and local inhibition in the superior colliculus.

Effect of Cue-target Onset Asynchrony (CTOA) and Cue Validity on Visual Vigilance Task Performance

Effect of Cue-target Onset Asynchrony (CTOA) and Cue Validity on Visual Vigilance Task Performance

Inhibition of return revisited: Localized inhibition on top of a pervasivebias.

An inhibitory after-effect of attention, frequently referred to as inhibition of return (IOR), operates at a previously attended location to discourage perseverative orienting. Using the classic cueing task, previous work has shown that IOR is not restricted to a previously attended location, but rather spreads to adjacent visual space in a graded manner. The present study expands on this earlier work by exploring a wider visual region and a broader range of cue-target onset asynchronies (CTOAs) to characterize the temporal dynamics of the IOR gradient. The results reveal that the magnitude of IOR generated by cueing decreases exponentially as the CTOA increases. The width of the IOR gradient first increases and then decreases, with a temporal profile that is well captured by an alpha function. Importantly, the present study reveals that in addition to its rapidly decaying local properties, cue-induced IOR can include a pervasive inhibitory bias, which remains relatively stable across IOR's lifetime.

Temporal ambiguity of onsets in a cueing task prevents facilitation but not inhibition of return.

Cueing effects, i.e., early facilitation of reaction time and inhibition of return (IOR), are well-established and robust phenomena characterizing exogenous orienting and are widely observed in experiments with a traditional Posner cueing paradigm. Krüger, MacInnes, and Hunt (2014) proposed that facilitatory effects of peripheral cues are the result of a cue-target perceptual merging due to re-entrant visual processing. To test the role and timing of these feedback mechanisms in peripheral cueing effects, we modified the traditional cueing task in Experiments 1-3 by interleaving pre- and post-cue trials at the valid and invalid location and random cue-target onset asynchrony (CTOA) ranging from -300 to +1,000 ms. Analysis of the manual reaction time distribution over CTOA showed well-pronounced IOR in the valid pre-cue condition and a small cost of perceptual merging in the post-cue condition, but no early facilitation of reaction time was observed in the pre-cue condition. In Experiment 4, we tested directly whether temporal ambiguity eliminated facilitation by restricting CTOAs to only the pre-cue time range and including a between-subject manipulation of a) random, b) mixed discrete, and c) blocked discrete CTOAs. Results obtained in the continuous and binned conditions showed no facilitation but robust IOR. We found both early facilitation and IOR in the blocked condition. Overall, the present findings show a small perceptual merging result without accompanying facilitation, suggesting different underlying mechanisms. Second, they demonstrate that early facilitation is likely to be affected by the presence or absence of temporal expectations and that the early onset of IOR might be masked by stronger facilitation in traditional cueing experiments.

The Time Course of Inhibition of Return: Evidence from Steady-State Visual Evoked Potentials.

Inhibition of return (IOR) refers to slower responses to targets at a previously cued location than that at an uncued location. The time course of IOR has long been a topic of interest in the field. Investigations into the time course of IOR are typically performed by examining the magnitude of IOR under various cue-target onset asynchrony (CTOA) conditions. Therefore, the results are vulnerable to influence of factors that could affect the target processes (e.g., the frequency of the target type). In the present study, steady-state visual evoked potentials (SSVEPs) were implemented to directly take a continuous measurement of the degree to which cued location is processed, eliminating the influence mentioned above. The results indicate that, relative to the baseline interval (−400 to 0 ms), the presence of peripheral cues generated a typical two-stage effect on the SSVEP amplitude evoked by a 20 Hz flicker. Specifically, after the onset of the peripheral cues, the SSVEP amplitude first showed a significant increase, which subsequently turned into a significant inhibition effect after 200 ms. These results provide a continuous time course diagram of the cueing effect and suggest an effective way for future investigations of controlling the masking effects of target stimuli processing on IOR.

Informative Cues Facilitate Saccadic Localization in Blindsight Monkeys.

Patients with damage to the primary visual cortex (V1) demonstrate residual visual performance during laboratory tasks despite denying having a conscious percept. The mechanisms behind such performance, often called blindsight, are not fully understood, but the use of surgically-induced unilateral V1 lesions in macaque monkeys provides a useful animal model for exploring such mechanisms. For example, V1-lesioned monkeys localize stimuli in a forced-choice condition while at the same time failing to report awareness of identical stimuli in a yes-no detection condition, similar to human patients. Moreover, residual cognitive processes, including saliency-guided eye movements, bottom-up attention with peripheral non-informative cues, and spatial short-term memory, have all been demonstrated in these animals. Here we examined whether post-lesion residual visuomotor processing can be modulated by top-down task knowledge. We tested two V1-lesioned monkeys with a visually guided saccade task in which we provided an informative foveal pre-cue about upcoming target location. Our monkeys fixated while we presented a leftward or rightward arrow (serving as a pre-cue) superimposed on the fixation point (FP). After various cue-target onset asynchronies (CTOAs), a saccadic target (of variable contrast across trials) was presented either in the affected (contra-lesional) or seeing (ipsi-lesional) hemifield. Critically, target location was in the same hemifield that the arrow pre-cue pointed towards in 80% of the trials (valid-cue trials), making the cue highly useful for task performance. In both monkeys, correct saccade reaction times were shorter during valid than invalid trials. Moreover, in one monkey, the ratio of correct saccades towards the affected hemifield was higher during valid than invalid trials. We replicated both reaction time and correct ratio effects in the same monkey using a symbolic color cue. These results suggest that V1-lesion monkeys can use informative cues to localize stimuli in the contra-lesional hemifield, consistent with reports of a human blindsight subject being able to direct attention in cueing paradigms. Because the superior colliculus (SC) may contribute to residual visual capabilities after V1 lesions, and because this structure is important for controlling attentional resources, we hypothesize that our results reflect, among others, SC involvement in integrating top-down task knowledge for guiding orienting behavior.

Where Does Attention Go When Facilitation is Absent?

Attending a location in space facilitates responses to targets at that location when the time between cue and target is short. Certain types of exogenous cues – such as sudden peripheral onsets – have been described as reflexive and automatic. Recent studies however, have been showing many cases where exogenous cues are less automatic than previously believed and do not always result in facilitation. Given a lack of the behavioural facilitation, we propose to test whether this also suggests a lack of underlying attention to that location. We test exogenous cueing with saccadic responses at a range of cue-target onset asynchronies (CTOAs), but also alternate measures linked to the allocation of attention such as saccadic curvature, microsaccades and pupil size. As expected, we find no early facilitation at short CTOAs, and likewise no impact of the cue on microsaccade direction or pupil size. We do observe a small dip in the frequency of microsaccades after the cue as well as a tendency for saccadic curvature away from the cued location at short CTOAs. We interpret these results as evidence of reduced attention at the cued location that is removed or inhibited too quickly to be measured as facilitation of saccadic responses.

Multiple Diffusion Models to Compare Saccadic and Manual Responses for Inhibition of Return.

Cuing a location in space produces a short-lived advantage in reaction time to targets at that location. This early advantage, however, switches to a reaction time cost and has been termed inhibition of return (IOR). IOR behaves differently for different response modalities, suggesting that it may not be a unified effect. This letter presents new data from two experiments testing the gradient of IOR with random, continuous cue-target Euclidean distance and cue-target onset asynchrony. These data were then used to train multiple diffusion models of saccadic and manual reaction time for these cuing experiments. Diffusion models can generate accurate distributions of reaction time data by modeling a response as a buildup of evidence toward a response threshold. If saccadic and attentional IOR are based on similar processes, then differences in distribution will be best explained by adjusting parameter values such as signal and noise within the same model structure. Although experimental data show differences in the timing of IOR across modality, best-fit models are shown to have similar model parameters for the gradient of IOR, suggesting similar underlying mechanisms for saccadic and manual IOR.

Inhibitory cueing effects following manual and saccadic responses to arrow cues.

With two cueing tasks, in the present study we examined output-based inhibitory cueing effects (ICEs) with manual responses to arrow targets following manual or saccadic responses to arrow cues. In all experiments, ICEs were observed when manual localization responses were required to both the cues and targets, but only when the cue-target onset asynchrony (CTOA) was 2,000ms or longer. In contrast, when saccadic responses were made in response to the cues, ICEs were only observed with CTOAs of 2,000ms or less-and only when an auditory cue-back signal was used. The present study also showed that the magnitude of ICEs following saccadic responses to arrow cues decreased with time, much like traditional inhibition-of-return effects. The magnitude of ICEs following manual responses to arrow cues, however, appeared later in time and had no sign of decreasing even 3s after cue onset. These findings suggest that ICEs linked to skeletomotor activation do exist and that the ICEs evoked by oculomotor activation can carry over to the skeletomotor system.