Stimulus Onset Asynchrony Research Articles

Limb apparent motion perception: Modification by tDCS, and clinically or experimentally altered bodily states

Limb apparent motion perception (LAMP) refers to the illusory visual perception of a moving limb upon observing two rapidly alternating photographs depicting the same limb in two different postures. Fast stimulus onset asynchronies (SOAs) induce the more visually guided perception of physically impossible movements. Slow SOAs induce the perception of physically possible movements. According to the motor theory of LAMP, the latter perception depends upon the observer's sensorimotor representations. Here, we tested this theory in two independent studies by performing a central (study 1) and peripheral (study 2) manipulation of the body's sensorimotor states during two LAMP tasks. In the first sham-controlled transcranial direct current stimulation between-subject designed study, we observed that the dampening of left sensorimotor cortex activity through cathodal stimulation biased LAMP towards the more visually guided perception of physically impossible movements for stimulus pairs at slow SOAs. In the second, online within-subject designed study, we tested three participant groups twice: (1) individuals with an acquired lower limb amputation, either while wearing or not wearing their prosthesis (2) individuals with body integrity dysphoria (i.e., with a desire for amputation of a healthy leg) while sitting in a regular position or binding up the undesired leg (to simulate the desired amputation); (3) able-bodied individuals while sitting in a normal position or sitting on one of their legs. We found that the momentary sensorimotor state crucially impacted LAMP in individuals with an amputation and able-bodied participants, but not in BID individuals. Taken together, the results of these two studies substantiate the motor theory of LAMP.

Controlled or automatic? Influence of congruency proportion and stimulus-onset asynchrony on the brightness-valence and spatial-valence metaphoric congruency effects

Whether a cognitive process is operated automatically or in a controlled manner has been a long-standing question in cognitive psychology. However, this issue has not been investigated in the activation of metaphoric association. A primed word valence judgement task is often used to test the activation of metaphoric association, in which participants first see a prime (bright/dark square or fixation point moving up or down from the centre of the screen) and then make a valence judgement to a target word. Metaphoric congruency effect occurs when participants make faster judgements to the target with valence being matched with the prime (good followed bright/top prime) than being mismatched with the prime (good followed dark/bottom prime). In the present two experiments, we manipulated prime-target stimulus-onset asynchrony (SOA) and proportion of metaphorically congruent trials (congruency proportion) to tease apart the effects of automatic and controlled activation of brightness-valence and spatial-valence metaphoric associations on word valence judgements. Results showed an overall effect of congruency proportion on brightness-valence and spatial-valence metaphoric congruency effect, which was independent of prime-target SOA. The effect was enhanced or reversed when congruency proportion was higher or lower than 0.5, respectively, suggesting that the activation of metaphoric association could be modulated by strategic control. The implications of these findings on the Conceptual Metaphor Theory and semantic priming theories are discussed.

Social orienting of attention: A meta-analytic review of the gaze-cueing effect

Reflexively following the eye gaze of others is thought to be a fundamental mechanism of human social cognition. In line with this, a gaze-cueing effect – whereby, healthy adults respond faster to peripheral targets presented at gazed-at rather than gazed-away-from locations – has been observed in the empirical literature. However, from both a methodological and theoretical perspective, many important questions remain about the potential role of moderator variables in understanding this effect. To directly address these, we conducted the first meta-analytic integration of the gaze-cueing literature. Integrating data from 3693 healthy adult participants from 112 independent samples, we found a small but significant gaze-cueing effect, g = 0.23. Although robust, emerging at all levels of each of the task parameters we examined, the magnitude of this effect was moderated by three key variables: namely, whether direct-gaze cues had preceded each directional gaze-cue or not, whether gaze-cues had disappeared before targets appeared or not, and whether the task had been to detect, localize, or categorize targets. The magnitude of the gaze-cueing effect also appeared to vary as a function of the emotional expression of the cue and the stimulus onset asynchrony (SOA) between cue and target. Although one significant moderating effect of cue ecological validity emerged at 600ms SOA, cue ecological validity was largely not a moderator of the gaze-cueing effect. Overall, this meta-analysis suggests that eye gaze is indeed a powerful social cue that reliably influences the allocation of others’ visual attention, but that this effect can be strengthened or reduced as a function of other social perceptual cues such as emotional expression and prior eye contact. Our findings also have implications for our understanding of the roles that task requirements, cue ecological validity, and SOA have on the gaze-cueing effect.

Does ensemble priming survive masking?

In everyday life, we feel that our perception of the world is detailed, while our reports of it are poor (Simons & Chabris, 1999, Simons & Levin, 1997). Cohen, Dennett, and Kanwisher (2016) proposed that our rich perceptual experience can be explained by the ability of our visual system to extract ensemble statistics from groups of objects. Ensemble statistics computation overcomes many limits of perception - for instance, it is robust to inattention (Alvarez & Oliva, 2008). However, it is unknown whether ensemble statistics can be computed without awareness. In the present study, we tested the hypothesis that masked ensemble statistics can prime individual stimuli. The participants (n = 45) were presented with an ensemble of oriented gratings and asked to report whether a subsequently presented test grating was tilted to the right or to the left. The test grating had either the mean ensemble orientation, one of the members’ orientations, or an explicit non-member orientation. The ensemble was backward and forward masked and we manipulated the stimulus-onset asynchrony between the masks and the ensemble. In the aware condition, there was a 160 ms blank between the masks and the ensemble. In the unaware condition, there was no blank. Additionally, the participants completed two control tasks to assess whether the awareness manipulation was successful. The results show a main effect of the test orientation: the reaction times were lowest for the mean orientation, higher for member orientation, and highest for non-member orientation. The control tasks revealed that the ensemble was harder to detect in the 0 ms SOA condition, but it was not completely invisible. These results show that priming by masked ensembles is possible, yet it is unclear whether the priming effects stem from unconscious processing.

Bayesian adaptive model estimation to solve the speed accuracy tradeoff problem in psychophysical experiments

Most psychological experiments measure human cognitive function through the response time and accuracy of the response to a set of stimuli. Since response time and accuracy complement each other, it is often difficult to interpret cognitive performance based on only one dependent measurement and raises a speed-accuracy tradeoff (SAT) problem. In overcoming this problem, SAT experimental paradigms and models that integrate response time and accuracy have been proposed to understand information processing in human cognitive function. However, due to a lengthy SAT experiment for reliable model estimation, SAT experiments' practical limitations have been pointed out. Thus, these limitations call for an efficient technique to shorten the number of trials required to estimate the SAT function reliably. Instead of using a block's stimulus-onset asynchrony (SOA) accuracy with long block-based task trials, we introduced a Bayesian SAT function estimation using trial-by-trial response time and correctness, which makes SAT tasks flexible and easily extendable to multiple trials. We then proposed a Bayesian adaptive method to select optimal SOA by maximizing information gain to estimate model parameters. Simulation results showed that the proposed Bayesian adaptive estimation was highly efficient and robust for accuracy and precision of estimating SAT function by enabling "multiple-step ahead search."

The Effects of 40-Hz Binaural Beat on Working Memory

Aim of the study is to determine whether the auditory processing of temporal fine structure (TFS) is affected with normal aging, even in the presence of normal audiometric hearing and fine cognitive state; and, if it is, to see whether a comparable effect is also observed in the processing of a diotic change in sound envelope. The event-related potentials (ERPs) to binaural beats (BBs), which are the responses of the binaural mechanisms processing TFS of a sound, and the ERPs to diotic amplitude modulation (AM) stimuli, which are the responses of the monaural mechanisms processing the changes in its envelope, were recorded from thirteen young university students and ten senior but active university professors, all with normal hearing in low frequencies. To obtain directly the specific BB responses without confounding monaural frequency change-evoked responses, we used single-cycle BB stimuli with temporary sub-threshold frequency shifts. BBs of a 250-Hz tone and diotic AM of the same tone with similar perceptual salience were presented with 2-second stimulus onset asynchrony. The N1 components of the ERPs to both stimuli displayed notable age-dependent changes in their scalp topography and significant amplitude reduction and latency prolongation in the elderly. These amplitude and latency changes were at similar rates for the two stimulus types, implying that the auditory TFS and envelope processing mechanisms are proportionally affected by physiological aging. These results may serve as control data in future studies investigating the effect of aging-associated cognitive pathologies on auditory TFS processing.

Distracting tasks have persisting effects on young and older drivers’ braking performance

It is well established that car driving performance suffers when the driver concurrently engages in a distracting activity, such as talking on a cell phone. The present study investigates whether the effects of driver distraction are short-lived, or rather persist for some time. Age-related differences are evaluated as well. Sixty-three young and 61 older adults were tested in a driving simulator. They were asked to follow a lead car that drove at a constant speed, and to concurrently engage in a pseudorandom sequence of distracting tasks (typing, reasoning, memorizing). When the lead car braked, participants had to brake as well to prevent a collision. The stimulus onset asynchrony between the braking task and the last preceding distraction was 11.49 ± 1.99 s. Each person was tested once in a multitasking condition (as described above), and once in a control condition without distracting tasks. Outcome measures quantified distance keeping and lane keeping while participants braked to the lead car. We found that braking responses differed significantly between conditions; this difference could be interpreted as a combination of performance deficits and compensatory strategies in the multitasking condition compared to the control condition. We also found significant differences between age groups, which could be interpreted similarly. Differences between age groups were less pronounced in the multitasking than in the control condition. All observed effects were associated with participants’ executive functioning. Our findings confirm that distractions have an impact on braking responses, and they document for the first time that this impact can persist for about 11.5 s. We attribute this persistence to a task set effect, and discuss the practical relevance of our findings.

First- and second-order transformational apparent motion rely on common shape representations

When one figure is replaced with another that overlaps its spatial location, observers perceive an illusory, continuous shape change of the original object, a phenomenon known as transformational apparent motion (TAM). The current study investigated the extent to which TAM depends on a common, high-level shape representation that is independent of the shape-defining attribute. Specifically, we tested whether TAM is perceived similarly for both first- and second-order objects, defined by luminance and texture contrast, respectively. A compelling motion percept was observed in second-order TAM displays that was comparable to that seen in first-order TAM displays. Importantly, TAM for both stimulus classes showed the same pattern over a range of stimulus onset asynchronies. These results support the high-level shape account, indicating that TAM is driven by segmentation mechanisms that rely on high-level shape information rather than low-level visual characteristics.

Investigating facilitatory versus inhibitory effects of dynamic social and non-social cues on attention in a realistic space.

This study aimed to investigate the facilitatory versus inhibitory effects of dynamic non-predictive central cues presented in a realistic environment. Realistic human-avatars initiated eye contact and then dynamically looked to the left, right or centre of a table. A moving stick served as a non-social control cue and participants localised (Experiment 1) or discriminated (Experiment 2) a contextually relevant target (teapot/teacup). The cues movement took 500 ms and stimulus onset asynchronies (SOA, 150 ms/300 ms/500 ms/1000 ms) were measured from movement initiation. Similar cuing effects were seen for the social avatar and non-social stick cue across tasks. Results showed facilitatory processes without inhibition, though there was some variation by SOA and task. This is the first time facilitatory versus inhibitory processes have been directly investigated where eye contact is initiated prior to gaze shift. These dynamic stimuli allow a better understanding of how attention might be cued in more realistic environments.

Rhyming abilities in a dual-task in school-age children who stutter

PurposeWe compared school-age children who stutter (CWS) and age and gender matched control participants (CWNS) in a dual-task involving a word-level rhyming task and a tone task involving pitch decisions. MethodsParticipants were 30 children (CWS, n = 15) between 7 and 16 years. Auditory word – picture stimuli pairs from the rhyme task were categorized into nonrhyme (e.g., bear-cart), rhyme (e.g., bear-pear), and replica (e.g., bear-bear) categories. The effort associated with managing resources in the dual-task was varied through the manipulation of stimulus onset asynchrony (SOA) between the stimuli of the two tasks. Mixed methods analyses of the response time (RT, ms) and error (%) data were conducted with Group, Category, and SOA as the fixed effects and participants as the random effect. Age and phoneme awareness skills were included in the analyses. ResultsMore rhyming errors and a significant positive correlation between rhyming errors and age was observed in the CWS compared to the CWNS. Compared to the CWNS, a higher percentage of rhyming errors was observed in the rhyme than the nonrhyme and replica categories in the CWS in both the SOA conditions, and this effect was influenced by age and phoneme awareness skills. Analysis of the tone task data indicated that a subgroup of CWNS with higher phoneme awareness skills showed reduced RT difference between the long and the short SOA conditions thereby suggesting higher efficiency with resource allocation for dual tasking. Task-specific differences between the CWS and CWNS are interpreted to suggest limitations in the encoding of the phonological aspects of covert speech in a dual-task.

Defective Temporal Window of the Foveal Visual Processing in High Myopia.

PurposeTo investigate the temporal characteristics of visual processing at the fovea and the periphery in high myopia.MethodsEighteen low (LM, ≤ −0.50 and > −6.00 D) and 18 high myopic (HM, ≤ −6.00 D) participants took part in this study. The contrast thresholds in an orientation discrimination task under various stimulus onset asynchrony (SOA) masking conditions were measured at the fovea and a more peripheral area (7°) for the two groups. An elaborated perceptual template model (ePTM) was fit to the behavioral data for each participant.ResultsAn analysis of variance with three factors (SOA, degree of myopia and eccentricity) was performed on the threshold data. The interaction between SOA and degree of myopia in the fovea was significant (F (4, 128) = 2.66, P = 0.036), suggesting that the masking effect had different temporal patterns between the two groups. The temporal profiles for the two groups were derived based on the ePTM model. The peak and the spread of the temporal window in the fovea were much lower and wider, respectively, in the HM group than that in the LM group (both Ps < 0.05). There was no significant difference in the peripheral temporal window between the two groups.ConclusionsHigh myopia is associated with defective temporal processing in the fovea, captured by a flattened temporal window.

Temporal Characteristics of Visual Processing in Amblyopia.

PurposeAmblyopia affects not only spatial vision but also temporal vision. In this study, we aim to investigate temporal processing deficits in amblyopia.MethodsTwenty amblyopic patients (age: 27.0 ± 5.53 years, 15 males), and 25 normal observers (age: 25.6 ± 4.03 years, 15 males) were recruited in this study. Contrast thresholds in an orientation discrimination task in five target-mask stimulus onset asynchronies (SOA) conditions (16.7 ms, 33.4 ms, 50.0 ms, 83.4 ms, and ∞/no noise) were measured. An elaborated perceptual template model (ePTM) was fit to the behavioral data to derive the temporal profile of visual processing for each participant.ResultsThere were significant threshold differences between the amblyopic and normal eyes [F(1,43) = 10.6, p = 0.002] and a significant group × SOA interaction [F(2.75,118) = 4.98, p = 0.004], suggesting different temporal processing between the two groups. The ePTM fitted the data well (χ2 test, all ps > 0.50). Compared to the normal eye, the amblyopic eye had a lower template gain (p = 0.046), and a temporal window with lower peak and broader width (all ps < 0.05). No significant correlation was found between the observed temporal deficits and visual acuity in amblyopia (ps > 0.50). Similar results were found in the anisometropic amblyopia subgroup. No significant difference was found between the fellow eyes of the monocular amblyopia and the normal eyes.ConclusionAmblyopia is less efficient in processing dynamic visual stimuli. The temporal deficits in amblyopia, represented by a flattened temporal window, are likely independent of spatial vision deficits.

Measuring the sensitivity of tactile temporal order judgments in sighted and blind participants using the adaptive psi method.

Spatial locations of somatosensory stimuli are coded according to somatotopic (anatomical distribution of the sensory receptors on the skin surface) and spatiotopic (position of the body parts in external space) reference frames. This was mostly evidenced by means of temporal order judgment (TOJ) tasks in which participants discriminate the temporal order of two tactile stimuli, one applied on each hand. Because crossing the hands generates a conflict between anatomical and spatial responses, TOJ performance is decreased in such posture, except for congenitally blind people, suggesting a role of visual experience in somatosensory perception. In previous TOJ studies, stimuli were generally presented using the method of constant stimuli-that is, the repetition of a predefined sample of stimulus-onset asynchronies (SOA) separating the two stimuli. This method has the disadvantage that a large number of trials is needed to obtain reliable data when aiming at dissociating performances of groups characterized by different cognitive abilities. Indeed, each SOA among a large variety of different SOAs should be presented the same number of times irrespective of the participant's performance. This study aimed to replicate previous tactile TOJ data in sighted and blind participants with the adaptive psi method in order to validate a novel method that adapts the presented SOA according to the participant's performance. This allows to precisely estimate the temporal sensitivity of each participant while the presented stimuli are adapted to the participant's individual discrimination threshold. We successfully replicated previous findings in both sighted and blind participants, corroborating previous data using a more suitable psychophysical tool.

Audiovisual Simultaneity Judgements in Synaesthesia.

Synaesthesia is a multimodal phenomenon in which the activation of one sensory modality leads to an involuntary additional experience in another sensory modality. To date, normal multisensory processing has hardly been investigated in synaesthetes. In the present study we examine processes of audiovisual separation in synaesthesia by using a simultaneity judgement task. Subjects were asked to indicate whether an acoustic and a visual stimulus occurred simultaneously or not. Stimulus onset asynchronies (SOA) as well as the temporal order of the stimuli were systematically varied. Our results demonstrate that synaesthetes are better in separating auditory and visual events than control subjects, but only when vision leads.

A question of (perfect) timing: A preceding head turn increases the head-fake effect in basketball

In many kinds of sports, deceptive actions are frequently used to hamper the anticipation of an opponent. The head fake in basketball is often applied to deceive an observer regarding the direction of a pass. To perform a head fake, a basketball player turns the head in one direction, but passes the ball to the opposite direction. Several studies showed that reactions to passes with head fakes are slower and more error-prone than to passes without head fakes (head-fake effect). The aim of a basketball player is to produce a head-fake effect for as large as possible in the opponent. The question if the timing of the deceptive action influences the size of the head-fake effect has not yet been examined systematically. The present study investigated if the head-fake effect depends on the temporal lag between the head turn and the passing movement. To this end, the stimulus onset asynchrony between head turn, and pass was varied between 0 and 800 ms. The results showed the largest effect when the head turn precedes the pass by 300 ms. This result can be explained better by facilitating the processing of passes without head fake than by making it more difficult to process passes with a head fake. This result is discussed regarding practical implications and conclusions about the underlying mechanism of the head–fake effect in basketball are drawn.

Electrophysiological evidence for the coexistence of expectancy fulfillment and semantic integration during the processing of binding and compound nouns

This study employed electrophysiological measures to investigate the processes of expectancy fulfillment and semantic integration during the processing of binding and compound nouns in Chinese. Sequential expectancy and cloze probability between the two constituents of a two-character noun were manipulated in two experiments, resulting in four types of target characters (i.e., the final characters of two-character nouns): (i) high-cloze, binding character (HB); (ii) high-cloze, compound character (HC); (iii) low-cloze, binding character (LB); (iv) low-cloze, compound character (LC). Participants were asked to judge as quickly and accurately as possible whether the two characters, presented sequentially, formed a real word. The two experiments varied in stimulus onset asynchrony (SOA) between the initial and the target characters: 1000 ms and 300 ms. ERPs acquired at the target characters revealed a significant semantic integration effect in both experiments whereby low-cloze target characters elicited more negative-going activities than high-cloze target characters (L > H) with both long and short SOAs. Importantly, there was a graded N400 effect (LC = LB > HC > HB) at the central region: a clearly visible positive deflection for HB relative to HC in synchrony with an equivalence in negativity for LB and LC. This graded pattern was observed with an SOA of 1000 ms but not 300 ms. These results are discussed in terms of the possible coexistence of an expectancy fulfillment mechanism indexed by the P300 that monitors incoming information for realization of expectancies based on stored mental representations and a semantic integration mechanism indexed by the N400 that incorporates incoming information into the preceding context based on semantic-pragmatic knowledge. Manifestation of this coexistence appears sensitive to SOA-modulated attention orientation.

Appraisal of definition of baseline length for somatosensory evoked magnetic fields

BackgroundThe baseline (BL) segment in the prestimulus period is generally assigned as a reference of evoked activities. However, an experimenter empirically defines its length in each condition. So far, the criterion for the length of a BL segment has not been established. New MethodWe evaluated the effect of the length of the BL segment by recording somatosensory evoked magnetic fields (SEFs) under fixed stimulus onset asynchrony (SOA). For the evaluation of the length of the BL segment in the prestimulus period, five proportions in relation to SOA were used as the BL segment. In addition, we adopted other two types of BL segment which were the single data point measured from the value of stimulus onset (BL0) and the mean value of the whole raw data throughout the recording (DC mean). We investigated the influence of the BL segments on SEFs by utilizing two indicators: normalized N20 m amplitudes and estimated locations of corresponding equivalent current dipoles (ECDs). ResultsBoth indicators did not show any significant differences, based on the factor of BL segments, in any SOA conditions. Comparison with Existing MethodThe BL0 had by far the largest variation in the ECD locations.Therefore, utilizing stimulus onset as the BL segment should be avoided. In addition, considering that other BL segments provided comparable values by the two indicators, the DC mean can reasonably be adopted. ConclusionsWe suggest that utilizing the DC mean could be employed as the BL segment.

Comparing person and people perception: Multiple group members do not increase stereotype priming.

A characteristic feature of daily life is encountering people in groups. Surprisingly, however, at least during the initial stages of processing, research has focused almost exclusively on the construal of single individuals. As such, it remains unclear whether person and people (i.e., group) perception yield comparable or divergent outcomes. Addressing this issue, here we explored a core social-cognitive topic—stereotype activation—by presenting both single and multiple facial primes in a sequential-priming task. In addition, the processes underlying task performance were probed using a drift diffusion model analysis. Based on prior work, it was hypothesised that multiple (vs. single) primes would increase stereotype-based responding. Across two experiments, a consistent pattern of results emerged. First, stereotype priming was insensitive to the number of primes that were presented and occurred only at a short prime-target stimulus onset asynchrony (i.e., 250 ms). Second, priming was underpinned by a bias towards congruent (vs. incongruent) prime-target responses. Collectively these findings advance understanding of the emergence and origin of stereotype priming during person and people perception.

Repeated application of the covert shift of attention task improves endogenous but not exogenous attention in patients with unilateral visuospatial inattention

BackgroundMost neglect treatment studies focus on automatic re-orientation procedures, assuming a deficit in automatic processes. We compare an automatic- and a controlled procedure, using the endogenous and exogenous variants of Posner’s covert shift of attention task. MethodIn two experiments, neglect patients and patients with a right hemispherical stroke without neglect performed three blocks of Posner’s covert shift of attention task (Posner Task) on two days. In Study 1 we used endogenous cues, in Study 2, exogenous cues. ResultsIn the endogenous task, neglect patients improved significantly with valid left-sided cues between block 1 and 2 on Day 1, subsequently showing a plateauing. They also showed a gradual improvement on invalid trials on both days. In the exogenous condition, all participants responded only increasingly faster on trials with a long stimulus onset asynchrony. Practicing on both tasks led to fewer omissions for left-sided targets, minimally in the exogenous and clearly in the endogenous condition. ConclusionIn line with prior neuroanatomical studies, our study shows that practicing an endogenous, but not an exogenous, visuospatial attention task leads to significant improvements in neglect patients, especially for invalid trials, suggesting that neglect treatments based on top-down strategies should be given more attention.

Visual-vestibular integration is preserved with healthy aging in a simple acceleration detection task

Aging is associated with a gradual decline in the sensory systems and noisier sensory information. Some research has found that older adults compensate for this with enhanced multisensory integration. However, less is known about how aging influences visual-vestibular integration, an ability that underlies self-motion perception. We examined how visual-vestibular integration changes in participants from across the lifespan (18–79 years old) with a simple reaction time task. Participants were instructed to respond to visual (optic flow) and vestibular (inertial motion) acceleration cues, presented either alone or at a stimulus onset asynchrony. We measured reaction times and computed the violation area relative to the race model inequality as a measure of visual-vestibular integration. Across all ages, the greatest visual-vestibular integration occurred when the vestibular cue was presented first. Age was associated with longer reaction times and a significantly lower detection rate in the vestibular-only condition, a finding that is consistent with an age-related increase in vestibular noise. Although the relationship between age and visual-vestibular integration was positive, the effect size was very small and did not reach statistical significance. Our results suggest that although age is associated with a significant increase in vestibular perceptual threshold, the relative amount of visual-vestibular integration remains largely intact.