Auditory Beeps Research Articles

Visual adaptation changes the susceptibility to the fission illusion.

Sound-induced flash illusion (SiFI) is the illusion that participants perceive incorrectly that the number of visual flashes is equal to the number of auditory beeps when presented within 100 ms. Although previous studies found that repetition suppression can reduce an individual's perceptual sensitivity to the SiFI, there is not yet a consensus as to how visual adaptation affects the SiFI. In the present study, we added prolonged adapting visual stimuli prior to the presentation of audiovisual stimuli to investigate whether the bottom-up factor of adaptation affects the SiFI. The adapting visual stimuli consisted of one or two of the same visual stimuli that lasted for 2 minutes in succession, followed by the audiovisual stimuli. Both adaptation conditions showed SiFI effects. The accuracy of adapting double-flashes was significantly lower than that of in adapting a single flash for the fission illusion. Our analyses indicated that such a pattern could be attributed to a lower d' in adapting double-flashes than in adapting a single flash. However, the accuracy, discriminability and criterion were not significantly different between the two adaptation conditions because of the instability of the fusion illusion. Thus, the present study indicated that the reduced perceptual sensitivity based on visual adaptation could enhance the fission illusion in multisensory integration.

Sensorimotor processing is dependent on observed speed during the observation of hand-hand and hand-object interactions.

Observing a physical interaction between individuals (e.g., observing friends shaking hands) or between an object and an individual (e.g., observing a teammate striking or being struck with a ball) can lead to somatosensory activation in the observer. However, it is not known whether the speed of the observed interaction modulates such somatosensory activation (e.g., observing a teammate being struck with a slow vs. a fast-moving ball). In three experiments, participants observed a hand or object interact with another hand or object, all presented with a slow- or fast-moving effector. To probe sensorimotor processes during observation, participants were asked to react to an auditory beep (i.e., response time [RT] task) at the moment of observed contact. If observed contact led to increased somatosensory activation, RTs would decrease due to statistical and/ or intersensory facilitation. In all three experiments, RTs were lower when observing fast compared to slow motion stimuli, regardless of the moving (i.e., hand or ball) and target stimulus (i.e., hand or leaf). Further, when only an object (i.e., leaf) was the target, RTs did not differ between the moving hand and moving ball condition. In contrast, when an object (i.e., ball) was used as the moving stimulus, the magnitude of the speed effect (i.e., fast - slow RT difference) was significantly larger when the ball contacted a hand as compared to a leaf. Overall, these results provide novel evidence for a relationship between the observed kinematics of an object-human interaction and the sensorimotor processing in the observer.

Sound-induced flash illusion is modulated by the depth of auditory stimuli: Evidence from younger and older adults

Sound-induced flash illusion (SiFI) refers to an auditory dominance effect in which observers misperceive the number of visual flashes due to the simultaneous presentation of a different number of auditory beeps. Although the SiFI remains robust despite many factors, little is known about how the dominance of audition over vision changes as a function of spatial location in 3D space and how this corresponds with aging. In the present study, we recruited younger (18-26 years old) and older adults (60-76 years old) and presented visual stimuli in near space and auditory stimuli in far space (Vnear_Afar) or visual stimuli in far space and auditory stimuli in near space (Vfar_Anear), with the aim of exploring the effect of aging on spatial dominance in SiFI. The results showed that both participant groups exhibited a SiFI auditory dominance effect; however, older adults were more susceptible to illusions than younger adults. More importantly, for younger adults, when auditory stimuli were presented in far space, the accuracy and d' indicated that SiFI was significantly enhanced in the fission illusion, and the reaction time (RT) results showed that RT became longer in the fusion illusion. However, for older adults, the SiFI was not affected by the spatial location. Therefore, the present results reveal for the first time that the SiFI effect is modulated by the depth of auditory stimuli. Moreover, older adults were not susceptible to the depth dimension, thus showing age-related sensory decline and specifically showing a decreased ability to localize visual and auditory stimuli.

Multisensory temporal binding induces an illusory gap/overlap that reduces the expected audiovisual interactions on saccades but not manual responses.

Throughout the day, humans react to multisensory events conveying both visual and auditory signals by rapidly reorienting their gaze. Several studies showed that sounds can impact the latency of visually guided saccades depending on when and where they are delivered. We found that unlocalized beeps delivered near the onset time of a visual target reduce latencies, more for early beeps and less for late beeps, however, this modulation is far weaker than for perceptual temporal judgments. Here we tested our previous assumption that beeps shift the perceived timing of target onset and result in two competing effects on saccade latencies: a multisensory modulation in line with the expected perceptual effect and an illusory gap/overlap effect, resulting from target appearance being perceived later/closer in time than fixation offset and shortening/lengthening saccade latencies. Gap/overlap effects involve an oculomotor component associated with neuronal activity in the superior colliculus (SC), a multisensory subcortical structure devoted to sensory-motor transformation. We therefore predicted that the interfering illusory gap/overlap effect would be weaker for manual responses, which involve distinct multisensory areas. In three experiments we manipulated the delay between target onset and an irrelevant auditory beep (stimulus onset asynchrony; SOA) and between target onset and fixation offset (real gap/overlap). Targets appeared left/right of fixation and participants were instructed to make quick saccades or button presses towards the targets. Adding a real overlap/gap (50% of SOA) compensated for the illusory gap/overlap by increasing the beep-related modulation of saccade latencies across the entire SOA range, whereas it barely affected manual responses. However, although auditory and gap/overlap effects modulated saccade latencies in similar ways, these were additive and could saturate, suggesting that they reflect independent mechanisms. Therefore, multisensory temporal binding affects perception and oculomotor control differently, likely due to the implication of the SC in saccade programming and multisensory integration.

Robust perceptual-load-dependent audiovisual integration in adult ADHD

We perceive our daily-life surrounded by different senses (e.g., visual, and auditory). For a coherent percept, our brain binds those multiple streams of sensory stimulations, i.e., multisensory integration (MI). Dependent on stimulus complexity, early MI is triggered by bottom–up or late via top–down attentional deployment. Adult attention-deficit/hyperactivity disorder (ADHD) is associated with successful bottom–up MI and deficient top–down MI. In the current study, we investigated the robustness of the bottom–up MI by adding additional task demand varying the perceptual load. We hypothesized diminished bottom–up MI for high perceptual load for patients with ADHD. 18 adult patients with ADHD and 18 age- and gender-matched healthy controls participated in this study. In the visual search paradigm, a target letter was surrounded by uniform distractors (low load) or by different letters (high load). Additionally, either unimodal (visual flash, auditory beep) or multimodal (audiovisual) flanked the visual search. Linear-mixed modeling was used to investigate the influence of load on reaction times. Further, the race model inequality was calculated. Patients with ADHD showed a similar degree of MI performance like healthy controls, irrespective of perceptual load manipulation. ADHD patients violated the race model for the low load but not for the high-load condition. There seems to be robust bottom–up MI independent of perceptual load in ADHD patients. However, the sensory accumulation might be altered when attentional demands are high.

The impact of joint attention on the sound-induced flash illusions

Humans coordinate their focus of attention with others, either by gaze following or prior agreement. Though the effects of joint attention on perceptual and cognitive processing tend to be examined in purely visual environments, they should also show in multisensory settings. According to a prevalent hypothesis, joint attention enhances visual information encoding and processing, over and above individual attention. If two individuals jointly attend to the visual components of an audiovisual event, this should affect the weighing of visual information during multisensory integration. We tested this prediction in this preregistered study, using the well-documented sound-induced flash illusions, where the integration of an incongruent number of visual flashes and auditory beeps results in a single flash being seen as two (fission illusion) and two flashes as one (fusion illusion). Participants were asked to count flashes either alone or together, and expected to be less prone to both fission and fusion illusions when they jointly attended to the visual targets. However, illusions were as frequent when people attended to the flashes alone or with someone else, even though they responded faster during joint attention. Our results reveal the limitations of the theory that joint attention enhances visual processing as it does not affect temporal audiovisual integration.

Did i do that? Cognitive flexibility and self-agency in patients with obsessivecompulsive disorder

Self-agency can be understood as the ability to infer causal relationships between actions and sensory events. Obsessive-Compulsive Disorder (OCD) patients with checking compulsions often report lack of “action-completion” sensations, possibly due to an altered sense of agency in these patients. The present study aimed to investigate whether self-agency was related to cognitive flexibility in OCD checkers. In 18 adult OCD checkers and 18 age- and gender-matched healthy controls, cognitive flexibility was assessed with the Intra-Extra Dimensional Set Shift Task (IED). Self-agency attribution was evaluated in two tasks that targeted the novel construct of “gaze-agency”, the capability of an observer to identify his or her own eye movements as the cause of a concurrent event (here, an auditory beep). This technique allows sensitive measurement of agency under subtly varying investigator-controlled conditions. OCD checkers manifested significantly inferior performance correctly ascribing the beeps to their own ocular saccades than controls, even when after a hint was provided. Although cognitive inflexibility (errors on the IED) did not differ significantly between the two groups, within the OCD sample there were positive correlations between errors in self-agency attribution and total and extra-dimensional shift errors. These findings show that cognitive inflexibility is related to self-agency in OCD.

Dynamic modulation of cortico-muscular coupling during real and imagined sensorimotor synchronisation

People have a natural and intrinsic ability to coordinate body movements with rhythms surrounding them, known as sensorimotor synchronisation. This can be observed in daily environments, when dancing or singing along with music, or spontaneously walking, talking or applauding in synchrony with one another. However, the neurophysiological mechanisms underlying accurately synchronised movement with selected rhythms in the environment remain unclear. Here we studied real and imagined sensorimotor synchronisation with interleaved auditory and visual rhythms using cortico-muscular coherence (CMC) to better understand the processes underlying the preparation and execution of synchronised movement. Electroencephalography (EEG), electromyography (EMG) from the finger flexors, and continuous force signals were recorded in 20 participants during tapping and imagined tapping with discrete stimulus sequences consisting of alternating auditory beeps and visual flashes. The results show that the synchronisation between cortical and muscular activity in the beta (14-38 Hz) frequency band becomes time-locked to the taps executed in synchrony with the visual and auditory stimuli. Dynamic modulation in CMC also occurred when participants imagined tapping with the visual stimuli, but with lower amplitude and a different temporal profile compared to real tapping. These results suggest that CMC does not only reflect changes related to the production of the synchronised movement, but also to its preparation, which appears heightened under higher attentional demands imposed when synchronising with the visual stimuli. These findings highlight a critical role of beta band neural oscillations in the cortical-muscular coupling underlying sensorimotor synchronisation.

Performing a task jointly enhances the sound-induced flash illusion.

Our senses are stimulated continuously. Through multisensory integration, different sensory inputs may or may not be combined into a unitary percept. Simultaneous with this stimulation, people are frequently engaged in social interactions, but how multisensory integration and social processing interact is largely unknown. The present study investigated if, and how, the multisensory sound-induced flash illusion is affected by a social manipulation. In the sound-induced flash illusion, a participant typically receives one visual flash and two auditory beeps and she or he is required to indicate the number of flashes that were perceived. Often, the auditory beeps alter the perception of the flashes such that a participant tends to perceive two flashes instead of one flash. We tested whether performing a flash counting task with a partner (confederate), who was required to indicate the number of presented beeps, would modulate this illusion. We found that the sound-induced flash illusion was perceived significantly more often when the flash counting task was performed with the confederate compared with performing it alone. Yet, we no longer find this effect if visual access between the two individuals is prevented. These findings, combined with previous results, suggest that performing a multisensory task jointly-in this case an audiovisual task-lowers the extent to which an individual attends to visual information, which in turn affects the multisensory integration process.

Deploying attention to the target location of a pointing action modulates audiovisual processes at nontarget locations.

The current study examined how the deployment of spatial attention at the onset of a pointing movement influenced audiovisual crossmodal interactions at the target of the pointing action and at nontarget locations. These interactions were quantified by measuring the susceptibility to the fission (i.e., reporting two visual flashes under one flash and two auditory beep pairings) and fusion (i.e., reporting one flash under two flashes and one beep pairing)audiovisual illusions. At movement onset, unimodal, or auditory and visual bimodal stimuli were either presented at the target of the pointing action or in an adjacent, nontarget location. In Experiment 1, perceptual accuracy within the unimodal and bimodal conditions was lower in the nontarget relative to the target condition. The fission illusion was uninfluenced by target condition. However, the fusion illusion was more likely to be reported at the target relative to the nontarget location. In Experiment 2, the stimulifrom Experiment 1 were further presented at a location near where the eyes were fixated (i.e., congruent condition), where the hand was aiming (i.e., target), or in a location where neither the eyes were fixated nor the hand was aiming. The results yielded the greatest susceptibility to the fusion illusion when the visual location and movement end points were congruent relative to when either movement or fixation was incongruent. Although attention may facilitate the processing of unisensoryand multisensory cues in general, attention might have the strongest influence on the audiovisual integration mechanisms that underlie the sound-induced fusion illusion.

The Dynamic Double Flash Illusion: Auditory Triggered Replay of Illusory Visual Expansion.

In the original double flash illusion, a visual flash (e.g., a sharp-edged disk, or uniformly filled circle) presented with two short auditory tones (beeps) is often followed by an illusory flash. The illusory flash has been previously shown to be triggered by the second auditory beep. The current study extends the double flash illusion by showing that this paradigm can not only create the illusory repeat of an on-off flash, but also trigger an illusory expansion (and in some cases a subsequent contraction) that is induced by the flash of a circular brightness gradient (gradient disk) to replay as well. The perception of the dynamic double flash illusion further supports the interpretation of the illusory flash (in the double flash illusion) as similar in its spatial and temporal properties to the perception of the real visual flash, likely by replicating the neural processes underlying the illusory expansion of the real flash. We show further that if a gradient disk (generating an illusory expansion) and a sharp-edged disk are presented simultaneously side by side with two sequential beeps, often only one visual stimulus or the other will be perceived to double flash. This indicates selectivity in auditory-visual binding, suggesting the usefulness of this paradigm as a psychophysical tool for investigating crossmodal binding phenomena.

Can rhythm-induced attention improve the perceptual representation?

Temporal attention can be entrained exogenously to rhythms. Indeed, faster and more accurate responses were previously found when the target appeared in-phase with a preceding rhythm in comparison to when it was out of phase. However, the nature of this rhythm-induced attentional effect is not well understood. To better understand the processes underlying rhythm-induced attention, we employed a continuous measure of perceived orientation and a mixture-model analysis. A trial in our study started with a sequence of auditory beeps separated by a fixed inter-beeps interval in the regular (rhythmic) condition or by variable inter-beeps intervals in the irregular condition. A visual target-a line embedded in a circle-followed the sequence. The 'critical' interval between the last beep and the target was chosen randomly from several possible Inter-Onset Intervals (IOIs), of which only one was in-phase with the rhythm. The target was followed by a probe line, and the participants were asked to rotate it to reproduce the target's orientation. The measure of performance for a given trial was the difference in degrees between the orientation of the target and that reproduced by the observer. We found that guessing rate was lower with regular than irregular rhythms. However, there was no effect of rhythm type (regular vs irregular) on the quality of representation (measured as the variability in reproducing the target). Furthermore, the rhythm effect was present only when rhythm type was fixed within a block, and it was found with all IOIs, not just the in-phase IOI. This lack of specificity suggests that these results reflect a general effect of rhythm on alertness.

Effects of Repetition Suppression on Sound Induced Flash Illusion With Aging.

The sound-induced flash illusion (SiFI) is a classical auditory-dominated multisensory integration phenomenon in which the observer misperceives the number of visual flashes due to the simultaneous presentation of a different number of auditory beeps. Although the SiFI has been documented to correlate with perceptual sensitivity, to date there is no consensus as to how it corresponds to sensitivity with aging. The present study was based on the SiFI paradigm (Shams et al., 2000), adding repeated auditory stimuli prior to the appearance of audiovisual stimuli to investigate the effects of repetition suppression (RS) on the SiFI with aging. The repeated auditory stimuli consisted of one or two of the same auditory stimuli presented twice in succession, which were then followed by the audiovisual stimuli. By comparing the illusions in old and young adults, we aimed to explore the influence of aging on the RS of auditory stimuli on the SiFI. The results showed that both age groups showed SiFI effects, however, the RS performance of the two age groups had different effects on the fusion and fission illusions. The illusion effect in old adults was weaker than in young adults. Specifically, RS only affected fission illusions in the old adults but both fission and fusion illusions in young adults. Thus, the present study indicated that the decreased perceptual sensitivity based on auditory RS could weaken the SiFI effect in multisensory integration and that old adults are more susceptible to RS, showing that old adults perceived the SiFI effect weakly under auditory RS.

Irrelevant auditory and tactile signals, but not visual signals, interact with the target onset and modulate saccade latencies.

Saccadic eye movements bring events of interest to the center of the retina, enabling detailed visual analysis. This study explored whether irrelevant auditory (experiments A, B & F), visual (C & D) or tactile signals (E & F) delivered around the onset of a visual target modulates saccade latency. Participants were instructed to execute a quick saccade toward a target stepping left or right from a fixation position. We observed an interaction between auditory beeps or tactile vibrations and the oculomotor reaction that included two components: a warning effect resulting in faster saccades when the signal and the target were presented simultaneously; and a modulation effect with shorter-or longer-latencies when auditory and tactile signals were delivered before-or after-the target onset. Combining both modalities only increased the modulation effect to a limited extent, pointing to a saturation of the multisensory interaction with the motor control. Interestingly, irrelevant visual stimuli (black background or isoluminant noise strips in peripheral vision, flashed for 10 ms) increased saccade latency whether they were presented just before or after target onset. The lack of latency reduction with visual signals suggests that the modulation observed in the auditory and tactile experiments was not related to priming effects but rather to low-level audio- and tactile-visual integration. The increase in saccade latency observed with irrelevant visual stimuli is discussed in relation to saccadic inhibition. Our results demonstrate that signals conveying no information regarding where and when a visual target would appear modulate saccadic reactivity, much like in multisensory temporal binding, but only when these signals come from a different modality.

Perceiving your hand moving: BOLD suppression in sensory cortices and the role of the cerebellum in the detection of feedback delays.

Sensory consequences of self-generated as opposed to externally generated movements are perceived as less intense and lead to less neural activity in corresponding sensory cortices, presumably due to predictive mechanisms. Self-generated sensory inputs have been mostly studied in a single modality, using abstract feedback, with control conditions not differentiating efferent from reafferent feedback. Here we investigated the neural processing of (a) naturalistic action-feedback associations of (b) self-generated versus externally generated movements, and (c) how an additional (auditory) modality influences neural processing and detection of delays. Participants executed wrist movements using a passive movement device (PMD) as they watched their movements in real time or with variable delays (0-417 ms). The task was to judge whether there was a delay between the movement and its visual feedback. In the externally generated condition, movements were induced by the PMD to disentangle efferent from reafferent feedback. Half of the trials involved auditory beeps coupled to the onset of the visual feedback. We found reduced BOLD activity in visual, auditory, and somatosensory areas during self-generated compared with externally generated movements in unimodal and bimodal conditions. Anterior and posterior cerebellar areas were engaged for trials in which action-feedback delays were detected for self-generated movements. Specifically, the left cerebellar lobule IX was functionally connected with the right superior occipital gyrus. The results indicate efference copy-based predictive mechanisms specific to self-generated movements, leading to BOLD suppression in sensory areas. In addition, our results support the cerebellum's role in the detection of temporal prediction errors during our actions and their consequences.

Synchronization Of Foot Strike And Cardiac Cycle During Treadmill Running In Non-endurance Trained Individuals

Synchronizing cardiac diastole with foot strike during running may maximize the efficiency with which skeletal muscle promotes venous return of blood to the heart. Recent research has found that diastolic stepping results in a lower heart rate (HR) compared to systolic stepping in elite endurance runners. PURPOSE: To assess HR, metabolic responses, and perceived exertion to running when foot strike occurs during either cardiac systole (CS) or cardiac diastole (CD) in non-endurance trained individuals. METHODS: Eight non-endurance trained participants (7 males; Age: 25.3 ± 8 yr; BMI: 23.6 ± 3.2 kg/m2) performed 2, 5-min bouts of treadmill running at a comfortable pace (5.4 ± 0.5 mph) with foot strike occurring during either CD or CS. Participants wore a chest strap that transmitted accelerometer and HR data to a tablet computer with proprietary software. The software generated an auditory beep that was synced with either 45% (CD) or 100% (CS) of each cardiac cycle. Participants were instructed to match their steps to the beeps during both conditions (CD or CS) which were randomized between trials and blinded to the participants. HR, oxygen consumption (VO2), O2-pulse, minute ventilation (VE), and respiratory exchange ratio (RER) were recorded continuously and averaged over the last 3 minutes of each condition. Rating of perceived Exertion (RPE) was recorded during the final minute of each condition. Paired T-tests were used to compare the dependent variables between conditions and all tests were considered significant at the 0.05 level. RESULTS: HR was significantly lower when foot strike occurred during CD compared with CS (163.0±5 vs. 170.1±4 bpm; P < 0.05). Furthermore, there was a trend for O2-pulse to be greater during CD (16.3±1.5 vs. 15.7±1.4 ml/beat; P = 0.07). VE (73.3±5 vs. 74.4±4 l/min), VO2 (35.0±1.3 vs. 35.3±1.2 ml/kg/min), and RPE (10.5±0.7 vs. 10.3±0.8) were not significantly different between CD and CS, respectively. CONCLUSION: During relatively short, steady-state running conditions, synchronization of foot strike with CD results in a significantly lower HR when compared to CS. This may lead to enhanced cardiac filling, which may be beneficial to running performance in non-endurance trained individuals.

The Effects of Visual Movement on Beat-Based vs. Duration-Based Temporal Perception

It is known that moving visual stimuli (bouncing balls) have an advantage over static visual ones (flashes) in sensorimotor synchronization, such that the former match auditory beeps in driving synchronization while the latter do not. This occurs in beat-based synchronization but not in beat-based purely perceptual tasks, suggesting that the advantage is action-specific. The main goal of this study was to test the advantage of moving over static visual stimuli in a different perceptual timing system – duration-based perception – to determine whether the advantage is action-specific in a broad sense, i.e., if it excludes both beat-based and duration-based perception. We asked a group of participants to perform different tasks with three stimulus types: auditory beeps, visual bouncing balls (moving) and visual flashes (static). First, participants performed a duration-based perception task in which they judged whether intervals were speeding up or slowing down; then they did a synchronization task with isochronous sequences; finally, they performed a beat-based perception task in which they judged whether sequences sounded right or wrong. Bouncing balls outperformed flashes and matched beeps in synchronization. In the duration-based perceptual task, beeps, balls and flashes were equivalent, but in beat-based perception beeps outperformed balls and flashes. Our findings suggest that the advantage of moving over static visual stimuli is grounded on action rather than perception in a broad sense, in that it is absent in both beat-based and duration-based perception.

Robust Temporal Averaging of Time Intervals Between Action and Sensation.

Perception of the time interval between one’s own action (a finger tapping) and the associated sensory feedback (a visual flash or an auditory beep) is critical for precise and flexible control of action and behavioral decision. Previous studies have examined temporal averaging for multiple time intervals and its role for perceptual organization and crossmodal integration. In the present study, we extended the temporal averaging from sensory stimuli to the coupling of action and its sensory feedback. We investigated whether and how temporal averaging could be achieved with respect to the multiple intervals in a sequence of action-sensory feedback events, and hence affect the subsequent timing behavior. In unimodal task, participants voluntarily tapped their index finger at a constant pace while receiving auditory feedback (beeps) with varied intervals as well as variances throughout the sequence. In crossmodal task, for a given sequence, each tap was accompanied randomly with either visual flash or auditory beep as sensory feedback. When the sequence was over, observers produced a subsequent tap with either auditory or visual stimulus, which enclose a probe interval. In both tasks, participants were required to make a two alternative forced choice (2AFC), to indicate whether the target interval is shorter or longer than the mean interval between taps and their associated sensory events in the preceding sequence. In both scenarios, participants’ judgments of the probe interval suggested that they had internalized the mean interval associated with specific bindings of action and sensation, showing a robust temporal averaging process for the interval between action and sensation.

Neural Correlates of Enhanced Audiovisual Processing in the Bilingual Brain

Bilingualism is associated with enhancements in perceptual and cognitive processing necessary for juggling multiple languages. Recent psychophysical studies demonstrate bilinguals also show enhanced multisensory processing and more restricted temporal binding windows for integrating audiovisual information. Here, we probed the neural mechanisms of bilinguals’ audiovisual benefits. We recorded neuroelectric responses in mono- and bi-lingual listeners to the double-flash paradigm in which auditory beeps concurrent with a single visual flash induces the perceptual illusion of multiple flashes. Relative to monolinguals, bilinguals showed less susceptibility to the illusion (fewer false perceptual reports) coupled with stronger and faster event-related potentials to audiovisual information. Source analyses of EEG data revealed monolinguals’ increased propensity for erroneously perceiving audiovisual stimuli was attributed to increased activity in primary visual (V1) and auditory cortex (PAC), increases in multisensory association areas (BA 37), but reduced frontal activity (BA 10). Regional activations were associated with an opposite pattern of behaviors: whereas stronger V1 and PAC activity predicted slower behavioral responses, stronger frontal BA10 responses elicited faster judgments. Our results suggest bilinguals’ higher precision in audiovisual perception reflects more veridical sensory coding of physical cues coupled with superior top-down gating of sensory information to suppress the generation of false percepts. Findings underscore that the plasticity afforded by speaking multiple languages shapes extra-linguistic brain regions and can enhance audiovisual brain processing in a domain-general manner.

Attentional Effort and Efficiency in Expert Dancers

Humans fluctuate naturally between two attentional states – characterized in some literature as good "on-task attention" and bad "mind wandering." However, these states can also be characterized in terms of attentional effort available (high vs. low). Here, we ask whether dancers have gained perceptual expertise that enables them to perform complex tasks even with divided attention or while in a "mind-wandering" state. In dance expertise, the effectively infinite movement possibilities dancers face when mimicking/learning dance sequences ensure that changes in required attentional effort are not attributable to proceduralization alone. Experiment 1 tested whether dance expertise transforms dance movement mimicry into a low-effort attention task. In a dual-task paradigm, we asked expert dancers (n=7) to watch and mimic 10s dance videos 1) with no secondary task, 2) while counting randomly presented auditory beeps, or 3) while performing mental math with the beeps. Subjects were recorded with an Xbox One Kinect sensor, and three expert dancers rated the movements' accuracy and timing. The dancers' performance was unaffected by either of the secondary attention tasks. Experiment 2 investigated whether, under naturally fluctuating attention, low-effort attention supports real-time reacting, but not remembering (due to added processing demands that require high-effort attention). Dancers (n=20) watched and mimicked dance videos, which stopped randomly every 40-80s. They indicated their attention state and tried to replicate their last few mimicked movements. Sensor recordings of the mimicked and replicated movements were analyzed using a Kinect machine learning gesture recognition software trained on the recordings from Experiment 1. As hypothesized, memory for the movements suffered significantly during low-effort attention (t=2.35, p=0.02), while real-time mimicry remained unimpaired (t=-0.45, p=0.67). These studies suggest that it may be adaptive (even optimal) to perform low-effort tasks in a mind-wandering state, and b) introduce a new method of studying complex actions with the Kinect. Meeting abstract presented at VSS 2018