Stimulus Onset Asynchrony Research Articles

Visual stimuli approaching toward the body influence temporal expectations about subsequent somatosensory stimuli

The present study investigated whether visual stimuli approaching the body influence temporal expectations about subsequent somatosensory stimuli. To examine this question, we recorded event-related brain potentials (ERPs) during a simple reaction time task using somatosensory stimuli. Fourteen participants were asked to place their arms on a desk, and three light-emitting diodes (LEDs) were placed at equal distances between their arms. Each trial was composed of three visual stimuli (i.e., LEDs), and one subsequent electrical stimulus (i.e., somatosensory stimulus) to one wrist. The stimulus onset asynchrony (SOA) between the visual stimuli was set to 1000ms. The SOA between the third visual stimulus and the somatosensory stimulus was set to 1000ms (standard; p=0.75), 500ms (early deviation; p=0.125), and 1500ms (late deviation; p=0.125). In the approach condition, the left, center, and right LEDs (or reverse) were turned sequentially toward the wrist to which the somatosensory stimulus was presented. In the neutral condition, the center LED was flashed three times. The N1 amplitudes for early deviations of stimuli were larger under the approach condition than under the neutral condition. These results show that prior visual stimuli facilitate temporal expectations about subsequent somatosensory stimuli, i.e., visual stimuli approaching toward the body facilitate the processing of early deviant stimuli. The present study indicates the existence of a function of supramodal temporal expectation and detection of deviation from this expectation using the approach of visual stimuli toward the body.

Was that a threat? Attentional biases by signals of threat.

The present study rigorously tests whether an arbitrary stimulus that signals threat affects attentional selection and perception. Thirty-four volunteers completed a spatial-emotional cueing paradigm to examine how perceptual sensitivity (d') and response times (RTs) were affected by a threatening stimulus. On each side of fixation, 2 colored circles were presented as cues, followed by 2 Gabor patches, 1 of which was tilted and served as target. The color of 1 of the cues was paired with an electric shock, while others remained neutral. The target could be presented at the location of the threat-associated cue (Valid), at the opposite side (Invalid), or following neutral cues. Stimulus onset asynchrony (SOA) between cue and target was either 100 ms or 1,000 ms. Results showed increased perceptual sensitivity (d') and faster RTs for targets appearing at the Valid location relative to the Invalidly cued location, suggesting that immediately after cue presentation, attention was captured by the threat-associated cue. Crucially, following this initial exogenous capture, there was also enhanced perceptual sensitivity at the long SOA, suggesting that attention lingered volitionally at the location that previously contained the threat-associated stimulus. The current results show an effect of threatening stimuli on perceptual sensitivity, providing unequivocal evidence that threatening stimuli modulate the efficacy of sensory processing. (PsycINFO Database Record

Reading sky and seeing a cloud: On the relevance of events for perceptual simulation.

Previous research has shown that processing words with an up/down association (e.g., bird, foot) can influence the subsequent identification of visual targets in congruent location (at the top/bottom of the screen). However, as facilitation and interference were found under similar conditions, the nature of the underlying mechanisms remained unclear. We propose that word comprehension relies on the perceptual simulation of a prototypical event involving the entity denoted by a word in order to provide a general account of the different findings. In 3 experiments, participants had to discriminate between 2 target pictures appearing at the top or the bottom of the screen by pressing the left versus right button. Immediately before the targets appeared, they saw an up/down word belonging to the target’s event, an up/down word unrelated to the target, or a spatially neutral control word. Prime words belonging to target event facilitated identification of targets at a stimulus onset asynchrony (SOA) of 250 ms (Experiment 1), but only when presented in the vertical location where they are typically seen, indicating that targets were integrated in the simulations activated by the prime words. Moreover, at the same SOA, there was a robust facilitation effect for targets appearing in their typical location regardless of the prime type. However, when words were presented for 100 ms (Experiment 2) or 800 ms (Experiment 3), only a location nonspecific priming effect was found, suggesting that the visual system was not activated. Implications for theories of semantic processing are discussed.

Dependent measure and time constraints modulate the competition between conflicting feature-based and rule-based generalization processes.

In our study, we tested the hypothesis that feature-based and rule-based generalization involve different types of processes that may affect each other producing different results depending on time constraints and on how generalization is measured. For this purpose, participants in our experiments learned cue-outcome relationships that followed the opposites rule: Single cues that signaled the same outcome (e.g., A-1/B-1) predicted the opposite outcome when presented in compound (e.g., AB-2). Some cues were only presented in compound during training (e.g., EF-1) to see if at test participants tended to generalize according to rule-based (i.e., E-2/F-2) or according to feature-based generalization (i.e., E-1/F-1). The generalization test used 2 different tasks: a predictive judgment task, and a cued-response priming task. In Experiment 1, participants' verbal ratings were consistent with rule-based generalization. However, participants' reaction times (RTs) in the cued-response priming task were consistent with feature-based generalization. Experiment 2 replicated the results from Experiment 1, and it also provided evidence consistent with feature-based or rule-based generalization depending on whether a short stimulus onset asynchrony (SOA; 200 ms) or a long SOA (1300 ms), respectively, was used in the priming task. Our results are interpreted as supporting the idea that feature-based generalization process relies on fast, associative processes, whereas rule-based generalization is slow and depends on executive control resources. The latter generalization process would inhibit the former when enough time and resources are available. Otherwise, feature-based generalization would take control of responses. (PsycINFO Database Record

Effects on P3 of spreading targets and response prompts apart

When key-press responses to targets have to be withheld until the presentation of response prompts, target-evoked P3 amplitudes are reduced and so is the P3 difference between rare and frequent targets (the oddball effect on P3). Recently we showed that this even applied when go-signals followed targets by 100ms. Here we aimed at replicating this result with more fine-grained temporal resolution in 100ms steps from 0ms to 500ms, and dissecting the P3 complex to stimulus- and response-related portions by applying residue iteration decomposition (RIDE). Frequent and rare target stimuli (in random series) were followed by go signals (and occasional no-go signals), with block-wise fixed stimulus-onset asynchronies (SOAs) from 0ms to 500ms. Target-evoked P3 amplitudes decreased monotonically across SOAs. Part of this decrease might have been due to an overlapping Contingent Negative Variation (CNV) prior to go signals, increasing across SOAs. When CNV was subtracted out by forming rare-frequent difference waveforms, oddball-P3 was largest at SOA 0, smallest at SOA 500, and equally large at SOAs 100–400. According to RIDE, it was P3's response-related part that was increased at SOA0. These results may be interpreted in terms of the stimulus-response-link reactivation hypothesis of P3.

Event Related Potentials Index Rapid Recalibration to Audiovisual Temporal Asynchrony.

Asynchronous arrival of multisensory information at the periphery is a ubiquitous property of signals in the natural environment due to differences in the propagation time of light and sound. Rapid adaptation to these asynchronies is crucial for the appropriate integration of these multisensory signals, which in turn is a fundamental neurobiological process in creating a coherent perceptual representation of our dynamic world. Indeed, multisensory temporal recalibration has been shown to occur at the single trial level, yet the mechanistic basis of this rapid adaptation is unknown. Here, we investigated the neural basis of rapid recalibration to audiovisual temporal asynchrony in human participants using a combination of psychophysics and electroencephalography (EEG). Consistent with previous reports, participant’s perception of audiovisual temporal synchrony on a given trial (t) was influenced by the temporal structure of stimuli on the previous trial (t−1). When examined physiologically, event related potentials (ERPs) were found to be modulated by the temporal structure of the previous trial, manifesting as late differences (>125 ms post second-stimulus onset) in central and parietal positivity on trials with large stimulus onset asynchronies (SOAs). These findings indicate that single trial adaptation to audiovisual temporal asynchrony is reflected in modulations of late evoked components that have previously been linked to stimulus evaluation and decision-making.

Integrative Priming of Compositional and Locative Relations.

Integrative priming refers to the facilitated recognition of a target word (bench) as a real word following a prime (park). Prior integrative priming studies have used a wide variety of integrative relations including temporal (summer rain), topical (travel book), locative (forest river), and compositional (peach pie) relations. Yet differences in the types of integrative relations may yield differences in the underlying explanatory processes of integrative priming. In this study, we compared the magnitude, time course, and three theoretically based correlates of integrative priming for compositional (stone table) and locative (patio table) pairs in a lexical decision task across four stimulus onset asynchronies (SOAs; 50, 300, 800, and 1,600 ms). Based on the Complementary Role Activation theory, integrative ratings (the extent to which the prime and target can be combined into a meaningful phrase) were predicted to facilitate target RTs. Based on the Embodied Conceptual Combination (ECCo) theory, the local co-occurrence of the prime and target, and the ability to perceptually simulate (visually experience) the prime-target pair were tested as predictors. In comparison to unrelated pairs (nose table), target RTs were faster for the compositional and locative pairs, though did not differ between these relations. In support of the Complementary Role Activation theory, integrative ratings predicted target RTs above and beyond our control variables. In support of the ECCo theory, co-occurrence emerged as an early predictor of target RTs, and visual experience ratings was a reliable predictor at the 300 ms SOA, though only for the compositional relations.

Hierarchical task organization in dual tasks: evidence for higher level task representations.

To examine whether hierarchical higher level task representations comprising the task sets of Task 1 (T1) and Task 2 (T2) are activated within each trial in dual-task situations, we combined the psychological refractory period (PRP) paradigm with the task-pair switching logic (Hirsch et al. 2017). In Experiment 1, in which subjects switched between task-pairs including a varying T1 and a constant T2, we found a PRP effect (i.e., worse performance with short stimulus onset asynchrony [SOA] than with long SOA) and task-pair switch costs in T1 and T2 (impaired performance in task-pair switches compared to task-pair repetitions). However, since in Experiment 1 there were no forward and backward response-response compatibility effects that indicated interference between T1 and T2, we could not exclude that the activation of T1 persisted into the next trial despite the intervening T2, and hence, that task-pair switch costs are due to repetition-priming effects of T1 across task-pairs rather than due to persisting activation of task-pair representations. In Experiment 2, we used a modified task-pair switching logic with a constant T1 and a varying T2, and replicated task-pair switch costs under conditions that not only rule out repetition-priming effects of T1 across task-pairs as the source of task-pair switch costs but also disentangle the effects of switching task-pairs from those of switching T1. These effects were associated in previous studies using the original task-pair switching logic. Thus, the findings of the present study strongly suggest that hierarchical higher level task representations are activated during dual-task processing.

Walking to a multisensory beat

Living in a complex and multisensory environment demands constant interaction between perception and action. In everyday life it is common to combine efficiently simultaneous signals coming from different modalities. There is evidence of a multisensory benefit in a variety of laboratory tasks (temporal judgement, reaction time tasks). It is less clear if this effect extends to ecological tasks, such as walking. Furthermore, benefits of multimodal stimulation are linked to temporal properties such as the temporal window of integration and temporal recalibration. These properties have been examined in tasks involving single, non-repeating stimulus presentations. Here we investigate the same temporal properties in the context of a rhythmic task, namely audio-tactile stimulation during walking. The effect of audio-tactile rhythmic cues on gait variability and the ability to synchronize to the cues was studied in young adults. Participants walked with rhythmic cues presented at different stimulus-onset asynchronies. We observed a multisensory benefit by comparing audio-tactile to unimodal stimulation. Moreover, both the temporal window of integration and temporal recalibration mediated the response to multimodal stimulation. In sum, rhythmic behaviours obey the same principles as temporal discrimination and detection behaviours and thus can also benefit from multimodal stimulation.

Temporal Binding Window of the Sound-Induced Flash Illusion in Amblyopia.

Amblyopia is a neurodevelopmental visual disorder caused by abnormal visual experience in childhood. In addition to known visual deficits, there is evidence for changes in audiovisual integration in amblyopia using explicit tasks. We examined audiovisual integration in amblyopia using an implicit task that is more relevant in a real-world context. A total of 11 participants with amblyopia and 16 controls were tested binocularly and monocularly on the sound-induced flash illusion, in which flashes and beeps are presented concurrently and the perceived number of flashes is influenced by the number of beeps. The task used 1 to 2 rapid peripheral flashes presented with 0 to 2 beeps, at 5 stimulus onset asynchronies, that is, beep (-200 milliseconds, -100 milliseconds) or flash leading (100 milliseconds, 200 milliseconds) or simultaneous (0 milliseconds). Participants reported the number of perceived flashes. Susceptibility was indicated by a "2 flashes" response to "fission" (1 flash, 2 beeps) or "1 flash" to "fusion" (2 flashes, 1 beep). For fission with the beep leading during binocular viewing, controls showed an expected decrease in illusion strength as stimulus onset asynchronies increased, whereas the illusion strength remained constant in participants with amblyopia, indicating a wider temporal binding window in amblyopia (P = 0.007). For fusion, participants with amblyopia showed reduced illusion strength during amblyopic eye viewing (P = 0.044) with the flash leading. Amblyopia is associated with the widening of the temporal binding window, specifically for fission when viewing binocularly with the beep leading. This suggests a developmental adaptation to delayed amblyopic eye visual processing to optimize audiovisual integration.

Distortions of temporal integration and perceived order caused by the interplay between stimulus contrast and duration.

Stimulus contrast and duration effects on visual temporal integration and order judgment were examined in a unified paradigm. Stimulus onset asynchrony was governed by the duration of the first stimulus in Experiment 1, and by the interstimulus interval in Experiment 2. In Experiment 1, integration and order uncertainty increased when a low contrast stimulus followed a high contrast stimulus, but only when the second stimulus was 20 or 30ms. At 10ms duration of the second stimulus, integration and uncertainty decreased. Temporal order judgments at all durations of the second stimulus were better for a low contrast stimulus following a high contrast one. By contrast, in Experiment 2, a low contrast stimulus following a high contrast stimulus consistently produced higher integration rates, order uncertainty, and lower order accuracy. Contrast and duration thus interacted, breaking correspondence between integration and order perception. The results are interpreted in a tentative conceptual framework.

Masked emotional priming: A double dissociation between direct and indirect effects reveals non-conscious processing of emotional information beyond valence.

We demonstrate non-conscious processing beyond valence by employing the masked emotional priming paradigm (Rohr, Degner, & Wentura, 2012) with a stimulus-onset asynchrony (SOA) variation. Emotional faces were briefly presented and directly masked, followed by the target face, using a SOA of either 43ms or 143ms. Targets were categorized as happy, angry, fearful, or sad. With short SOA, we replicated the differentiated priming effect within the negative domain (i.e., angry differentiate from fearful/sad). A direct test of prime awareness indicated that primes could not be discriminated consciously in this condition. With long SOA, however, we did not observe the priming effect whereas the direct test indicated some degree of conscious processing. Thus, indirect effects dissociated from direct effects in our study, an indication for non-conscious processing. Thereby, the present study provides evidence for non-conscious processing of emotional information beyond a simple positive-negative differentiation.

Peripheral target identification performance modulates eye movements

We often shift our eyes to an interesting stimulus, but it is important to inhibit that eye movement in some environments (e.g., a no-look pass in basketball). Here, we investigated participants’ ability to inhibit eye movements when they had to process a peripheral target with a requirement to maintain strict fixation. An array of eight letters composed of four characters was briefly presented and a directional cue was centrally presented to indicate the target location. The stimulus onset asynchrony (SOA) between the cue and the stimulus array was chosen from six values, consisting of pre-cue conditions (−400 and −200ms), a simultaneous cue condition (0ms), and post-cue conditions (200, 400, and 800ms). We found the following: 1) participants shifted their eyes toward the cued location even though the stimulus array was absent at the onset of eye movements, but the eye movement amplitude was smaller than the actual location of the target; 2) eye movements occurred approximately 150ms after the onset of stimulus array in the pre-cue conditions and 250ms after cue onset in the simultaneous and post-cue conditions; and 3) eye movement onsets were delayed and their amplitudes were smaller in correct trials than incorrect trials. These results indicate that the inhibitory process controlling eye movements also compete for cognitive resources like other cognitive processes.

Individual differences in the dynamics of collinear facilitation?

Collinear facilitation refers to the increase in sensitivity found for a target when aligned between nearby, brighter flankers. Many studies have explored the spatial and temporal aspects of this arrangement, and there is a consensus that two mechanisms could be responsible for this phenomenon; lateral excitation within V1 and extra-striate feedback to V1. There is some debate as to whether facilitation can still occur if the target is presented before the flankers, a manipulation known as backward masking, which could rely on feedback to V1. We shed light on this debate by using forward, simultaneous and backward masking with a relatively large sample of 26 participants. We used short stimulus presentation times (35ms) and a range of SOAs (stimulus onset asynchronies) (−70, −35, 0, 35 and 70ms) in order to isolate any feedback facilitation that may occur. We found that collinear facilitation occurred with forward masking (+ve SOAs) in all participants. However, facilitation with backward masking (−ve SOAs) only occurred in 54% of participants. We present a basic model of facilitation that simulates the results of our experiment and could account for differences between previous studies. The model indicates that facilitation with backward masking arises primarily from feedback excitation. Our findings suggest that both lateral connectivity and extra-striate feedback contribute to target facilitation, but in fundamentally different ways and that feedback may be significantly reduced in some participants.

Compliance instead of flexibility? On age-related differences in cognitive control during visual search

The effect of healthy aging on cognitive control of irrelevant visual information was investigated by using event-related potentials. Participants performed a spatial cuing task where an irrelevant color cue that was either contingent (color search) or noncontingent (shape search) on the attentional set was presented before a target with different stimulus-onset asynchronies. In the contingent condition, attentional capture appeared independent of age and persisted over the stimulus-onset asynchronies but was markedly pronounced for elderly people. Accordingly, event-related potential analyses revealed that both older and younger adults initially selected the irrelevant cue when it was contingent on the attentional set and transferred spatial cue information into working memory. However, only younger adults revealed inhibitory mechanisms to compensate for attentional capture. It is proposed that this age-related lack of reactive inhibition leads to stickiness in visual processing whenever information is contingent on the attentional set, unveiling older adults' “Achilles' heel” in cognitive control.

Strategic control over extent and timing of distractor-based response activation.

In choice reaction time (RT) tasks, performance is often influenced by the presence of nominally irrelevant stimuli, referred to as distractors. Recent research provided evidence that distractor processing can be adjusted to the utility of the distractors: Distractors predictive of the upcoming target/response were more attended to and also elicited stronger motor responses. In an event-related potential (ERP) study, we investigated whether not only the extent of distractor processing (as suggested by these previous results), but also the timing of distractor-based response activation is subject to strategic control. In a temporal flanker task, in which a distractor stimulus preceded the target, we manipulated distractor utility (i.e., by varying the proportion of congruent distractor-target combinations, 75% vs. 25%) as well as the stimulus onset asynchrony (SOA) between distractors and targets (350 ms vs. 1,000 ms) in different blocks of trials. The distractor-locked lateralized readiness potential (LRP) was overall larger in blocks with a high proportion of congruent trials indicating stronger distractor-based response activation when distractor utility was high. Of importance, the LRPs occurred overall later when the SOA was long. This suggests that distractor-based response activation can be postponed and thus adjusted to the temporal factors of the context. Modulations of early visual potentials (P1 and N1) indicate that this postponement of motor activation is related to both sensory-perceptual downgrading of distractor stimuli and reduced activation of task-relevant stimulus-response transformation processes at the time of distractor perception. (PsycINFO Database Record

When Elderly Outperform Young Adults-Integration in Vision Revealed by the Visual Mismatch Negativity.

We studied the possibility of age-related differences of visual integration at an automatic and at a task-related level. Data of 15 young (21.9 ± 1.8 years) and 15 older (66.6 ± 3.5 years) women were analyzed in our experiment. Automatic processing was investigated in a passive oddball paradigm, and the visual mismatch negativity (vMMN) of event-related brain potentials was measured. Letters and pseudo-letters were presented either as single characters, or the characters were presented successively in two fragments. In case of simultaneous presentation of the two fragments (whole character) vMMN emerged in both age groups. However, in successive presentation vMMN was elicited only by the deviant pseudo-letters, and only in the older group. The longest stimulus onset asynchrony (SOA) in this group was 50 ms, indicating longer information persistence in elderly. In a psychophysical experiment, the task was to indicate, which member of a character pair was a legal letter. Again, the letters and pseudo-letters were presented as fragments. We obtained successful integration at 30 ms (0 ms interstimulus interval), but not at longer SOAs in both age groups, showing that in case of task-relevant stimulation level there was no detectable age-related performance difference. We interpreted the results as the efficiency of local inhibitory circuits is compromised in elderly, leading to longer stimulus persistence, and hence better visual perception in this particular case.

Reward interacts with modality shift to reduce cross-modal conflict.

Previous studies have shown that reward can enhance cognitive control and reduce conflict in visual processing. Here we investigate (a) whether and how reward influences cross-modal conflict control and (b) how the shift of attention across modalities modulates the effect of reward on cross-modal conflict control. In four experiments, a cue indicating the reward availability of a given trial (reward vs. no reward) was presented prior to a target. The target was either a visual or an auditory letter, which was accompanied by a distracting letter from the other modality. The identity of the distracting letter was either the same as or different from the identity of the target letter (congruent vs. incongruent). When the cue modality was constant (Experiment 1) or changed across different experimental blocks (Experiment 3), the interference effect (i.e., the response time difference between incongruent and congruent trials) was smaller following a reward cue than a no-reward cue, suggesting that reward can reduce cross-modal conflict. In contrast, when the cue modality was changed trial-by-trial in an unpredictable way (Experiments 2 and 4), reward reduced cross-modal conflict only when the cue and the target were from different modalities and had a long stimulus onset asynchrony (SOA) between them but not when they shared the same modality or had a short SOA between them. These results suggest that reward can facilitate cross-modal conflict resolution, and this effect may critically depend on both the preparatory state between the cue and the target and timing to initiate cognitive control.

Audiovisual Temporal Processing and Synchrony Perception in the Rat.

Extensive research on humans has improved our understanding of how the brain integrates information from our different senses, and has begun to uncover the brain regions and large-scale neural activity that contributes to an observer’s ability to perceive the relative timing of auditory and visual stimuli. In the present study, we developed the first behavioral tasks to assess the perception of audiovisual temporal synchrony in rats. Modeled after the parameters used in human studies, separate groups of rats were trained to perform: (1) a simultaneity judgment task in which they reported whether audiovisual stimuli at various stimulus onset asynchronies (SOAs) were presented simultaneously or not; and (2) a temporal order judgment task in which they reported whether they perceived the auditory or visual stimulus to have been presented first. Furthermore, using in vivo electrophysiological recordings in the lateral extrastriate visual (V2L) cortex of anesthetized rats, we performed the first investigation of how neurons in the rat multisensory cortex integrate audiovisual stimuli presented at different SOAs. As predicted, rats (n = 7) trained to perform the simultaneity judgment task could accurately (~80%) identify synchronous vs. asynchronous (200 ms SOA) trials. Moreover, the rats judged trials at 10 ms SOA to be synchronous, whereas the majority (~70%) of trials at 100 ms SOA were perceived to be asynchronous. During the temporal order judgment task, rats (n = 7) perceived the synchronous audiovisual stimuli to be “visual first” for ~52% of the trials, and calculation of the smallest timing interval between the auditory and visual stimuli that could be detected in each rat (i.e., the just noticeable difference (JND)) ranged from 77 ms to 122 ms. Neurons in the rat V2L cortex were sensitive to the timing of audiovisual stimuli, such that spiking activity was greatest during trials when the visual stimulus preceded the auditory by 20–40 ms. Ultimately, given that our behavioral and electrophysiological results were consistent with studies conducted on human participants and previous recordings made in multisensory brain regions of different species, we suggest that the rat represents an effective model for studying audiovisual temporal synchrony at both the neuronal and perceptual level.

Isolating component processes of posterror slowing with the psychological refractory period paradigm.

Posterror slowing (PES) refers to an increased response time following errors. While PES has traditionally been attributed to control adjustments, recent evidence suggested that PES reflects interference. The present study investigated the hypothesis that control and interference represent 2 components of PES that differ with respect to their time course and task-specificity. To this end, we investigated PES in a dual-task paradigm in which participants had to classify colors and tones that were separated by a variable stimulus onset asynchrony (SOA). Errors in the color task caused PES both in the tone task of the same trial and the color task of the subsequent trial. However, while the former effect disappeared with an increasing SOA, the latter effect was independent of SOA and lasted for several trials. This suggests that errors simultaneously induce task-unspecific, transient PES reflecting interference and task-specific, more long-lasting PES reflecting control adjustments. (PsycINFO Database Record