Multisensory perception of natural versus unnatural motion.

Previous research has shown that visual perception is influenced by Newtonian constraints. Kominsky et al. showed humans detect unnatural motion, where objects break Newtonian constraints by moving at a faster speed after colliding with another object, faster than collisions that do not violate Newtonian constraints. These findings show that the perceptual system distinguishes between realistic and unrealistic causal events. However, real-world collisions are rarely silent. The present study extends this research by including sound at the collision point between two objects to evaluate how multisensory integration influences the perception of natural versus unnatural colliding events. Participants viewed an array of three simultaneous videos, each depicting two objects moving in a horizontal back and forth motion. Two of the videos showed the objects moving at the same speed while the third video was an oddball that either moved faster before the collision and slower after (natural target), or slower before the collision and faster after (unnatural target). A brief click was presented at the collision point of one or none of the videos. Participants were asked to indicate the oddball video via keypress. Replicating Kominsky et al., participants were faster when identifying unnatural target motion events compared with natural target motion events, both with and without sound. The findings also demonstrated lower accuracy rates for unnatural events compared with natural events, especially when a sound was added. These findings suggest that the addition of a sound could be distracting to participants, possibly due to limitations in attentional resources.

Sound-modulations of visual motion perception implicate the cortico-vestibular brain.

A widely used example of the intricate (yet poorly understood) intertwining of multisensory signals in the brain is the audiovisual bounce inducing effect (ABE). This effect presents two identical objects moving along the azimuth with uniform motion and towards opposite directions. The perceptual interpretation of the motion is ambiguous and is modulated if a transient (sound) is presented in coincidence with the point of overlap of the two objects' motion trajectories. This phenomenon has long been written-off to simple attentional or decision-making mechanisms, although the neurological underpinnings for the effect are not well understood. Using behavioural metrics concurrently with event-related fMRI, we show that sound-induced modulations of motion perception can be further modulated by changing motion dynamics of the visual targets. The phenomenon engages the posterior parietal cortex and the parieto-insular-vestibular cortical complex, with a close correspondence of activity in these regions with behaviour. These findings suggest that the insular cortex is engaged in deriving a probabilistic perceptual solution through the integration of multisensory data.

Achieving Flow: An Exploratory Investigation of Elite College Athletes and Musicians.

While studies on the characteristics of flow states and their relation to peak performance exist, little is known about the dynamics by which flow states emerge and develop over time. The current paper qualitatively explores the necessary pre-conditions to enter flow, and the development of flow over time until its termination. Using an elicitation interview, participants (10 athletes and 12 musicians) were asked to recall their flow experiences in sports or music performances. The analysis resulted in the identification of the following three phases that athletes and musicians experience during flow: (1) Preparation to enter flow; (2) Entry into the flow state and; (3) Exit from the flow state. These three phases are characterized by several sub-themes contributing to the experience of flow. The function of emotions is crucial, as they play a core role across all three phases and regulate flow over time. The findings provide insights into the phenomenological characteristics of the transition and maintenance of the three proposed phases and the temporal dynamics of flow.

Ageing and selective inhibition of irrelevant information in an attention-demanding rapid serial visual presentation task.

Attention involves both an ability to selectively focus on relevant information and simultaneously ignore irrelevant information (i.e. inhibitory control). Many factors impact inhibitory control such as individual differences, relative timing of stimuli presentation, distractor characteristics, and participant age. Previous research with young adults responding to an attention-demanding rapid serial visual presentations of pictures superimposed with task-irrelevant words evaluated the extent to which unattended information may be subject to inhibitory control. Surprise recognition tests following the rapid serial visual presentation task showed that recognition for unattended words presented with non-targets (i.e. non-aligned or 'NA' words) during the rapid serial visual presentation task were recognised at chance levels. However, when the unattended words were infrequently paired with the attended picture targets (i.e. target-aligned or 'TA' words), recognition rates were significantly below chance and significantly lower compared to NA words, suggesting selective inhibitory control for the previously unattended TA words. The current study adapted this paradigm to compare healthy younger and older adults' ability to engage in inhibitory control. In line with previous research, younger adults demonstrated selective inhibition with recognition rates for TA words significantly lower than NA words and chance, while NA words were recognised at chance levels. However, older adults showed no difference in recognition rates between word types (TA versus NA). Rather all items were recognised at rates significantly below chance suggesting inhibited recognition for all unattended words, regardless of when they were presented during the primary task. Finally, older adults recognised significantly fewer NA words compared to young adults. These findings suggest that older adults may experience a decline in their ability to selectively inhibit the processing of irrelevant information, while maintaining the capacity to exercise global inhibition over unattended lexical information.

Listen to Your Heart: Examining Modality Dominance Using Cross-Modal Oddball Tasks.

The current study used cross-modal oddball tasks to examine cardiac and behavioral responses to changing auditory and visual information. When instructed to press the same button for auditory and visual oddballs, auditory dominance was found with cross-modal presentation slowing down visual response times more than auditory response times (Experiment 1). When instructed to make separate responses to auditory and visual oddballs, visual dominance was found with cross-modal presentation decreasing auditory discrimination, and participants also made more visual-based than auditory-based errors on cross-modal trials (Experiment 2). Experiment 3 increased task demands while requiring a single button press and found evidence of auditory dominance, suggesting that it is unlikely that increased task demands can account for the reversal in Experiment 2. Auditory processing speed was the best predictor of auditory dominance, with auditory dominance being stronger in participants who were slower at processing the sounds, whereas auditory and visual processing speed and baseline heart rate variability did not predict visual dominance. Examination of cardiac responses that were time-locked with stimulus onset showed cross-modal facilitation effects, with auditory and visual discrimination occurring earlier in the course of processing in the cross-modal condition than in the unimodal conditions. The current findings showing that response demand manipulations reversed modality dominance and that time-locked cardiac responses show cross-modal facilitation, not interference, suggest that auditory and visual dominance effects may both be occurring later in the course of processing, not from disrupted encoding.

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.

The Quiet Eye and Expertise: Sustained Fixations Do Not Transfer to Unpracticed Throws Among Expert Dart Players.

The length of the last visual fixation before the critical final phase of a movement-the quiet eye (QE) fixation-is positively correlated with expertise and success. The present study tested the potential for intraskill transfer of QE durations in order to determine whether it is intrinsically linked to expertise development or is a separable skill that may be employed to improve performance under novel circumstances. The authors tracked highly skilled dart throwers' gazes while they executed familiar (highly practiced) and familiar yet novel (distance/effector-modified) sport-specific actions. QE duration was significantly reduced when performing in unfamiliar conditions, suggesting that QE does not transfer to atypical conditions and may therefore be a result of-rather than a contributor to-expertise development. These results imply that intraskill transfer of QE is limited and, consistent with the inhibition hypothesis of QE development, argue against the value of teaching QE as an independent means of improving performance.

Flow States and Associated Changes in Spatial and Temporal Processing.

Improved perception during high performance is a commonly reported phenomenon. However, it is difficult to determine whether these reported changes experienced during flow states reflect veridical changes in perceptual processing, or if instead are related to some form of memory or response bias. Flow is a state in which an individual experiences high focus and involvement in a specific task, and typically experiences a lack of distractibility, a disordered sense of time, great enjoyment, and increased levels of performance. The present pre-registered study investigated 27 athletes and musicians using a temporal order judgement (TOJ) task before and after a sports or music performance over three sessions. Participants' flow experiences were surveyed in order to measure how modulations of flow over successive performances potentially modulates spatiotemporal perception and processing. Hierarchical linear modeling showed a positive moderation of subjectively experienced flow and performance on post-measures of a TOJ task. Specifically, the higher the subjective flow experience of the sport or music performance was rated, the better the participant performed in the post-performance TOJ task compared to the pre-performance TOJ task. The findings of the present study provide a more comprehensive explanation of human perception during flow at high level performances and suggest important insights regarding the possibility of modulated temporal processing and spatial attention.

Stimulus Onset Modulates Auditory and Visual Dominance.

Investigations of multisensory integration have demonstrated that, under certain conditions, one modality is more likely to dominate the other. While the direction of this relationship typically favors the visual modality, the effect can be reversed to show auditory dominance under some conditions. The experiments presented here use an oddball detection paradigm with variable stimulus timings to test the hypothesis that a stimulus that is presented earlier will be processed first and therefore contribute to sensory dominance. Additionally, we compared two measures of sensory dominance (slowdown scores and error rate) to determine whether the type of measure used can affect which modality appears to dominate. When stimuli were presented asynchronously, analysis of slowdown scores and error rates yielded the same result; for both the 1- and 3-button versions of the task, participants were more likely to show auditory dominance when the auditory stimulus preceded the visual stimulus, whereas evidence for visual dominance was observed as the auditory stimulus was delayed. In contrast, for the simultaneous condition, slowdown scores indicated auditory dominance, whereas error rates indicated visual dominance. Overall, these results provide empirical support for the hypothesis that the modality that engages processing first is more likely to show dominance, and suggest that more explicit measures of sensory dominance may favor the visual modality.

Shared or Distinct Attentional Resources? Confounds in Dual Task Designs, Countermeasures, and Guidelines.

Human information processing is limited by attentional resources. That is, via attentional mechanisms humans select information that is relevant for their goals, and discard other information. While limitations of attentional processing have been investigated extensively in each sensory modality, there is debate as to whether sensory modalities access shared resources, or if instead distinct resources are dedicated to individual sensory modalities. Research addressing this question has used dual task designs, with two tasks performed either in a single sensory modality or in two separate modalities. The rationale is that, if two tasks performed in separate sensory modalities interfere less or not at all compared to two tasks performed in the same sensory modality, then attentional resources are distinct across the sensory modalities. If task interference is equal regardless of whether tasks are performed in separate sensory modalities or the same sensory modality, then attentional resources are shared across the sensory modalities. Due to their complexity, dual task designs face many methodological difficulties. In the present review, we discuss potential confounds and countermeasures. In particular, we discuss 1) compound interference measures to circumvent problems with participants dividing attention unequally across tasks, 2) staircase procedures to match difficulty levels of tasks and counteracting problems with interpreting results, 3) choosing tasks that continuously engage participants to minimize issues arising from task switching, and 4) reducing motor demands to avoid sources of task interference, which are independent of the involved sensory modalities.

Grunting's competitive advantage: Considerations of force and distraction.

BACKGROUND: Grunting is pervasive in many athletic contests, and empirical evidence suggests that it may result in one exerting more physical force. It may also distract one's opponent. That grunts can distract was supported by a study showing that it led to an opponent being slower and more error prone when viewing tennis shots. An alternative explanation was that grunting masks the sound of a ball being hit. The present study provides evidence against this alternative explanation by testing the effect of grunting in a sport-mixed martial arts-where distraction, rather than masking, is the most likely mechanism. METHODOLOGY/PRINCIPAL FINDINGS: We first confirmed that kicking force is increased when a grunt is performed (Experiment 1), and then adapted methodology used in the tennis study to mixed martial arts (Experiment 2). Lifting the foot to kick is a silent act, and therefore there is nothing for a grunt to mask, i.e., its effect on an opponent's response time and/or accuracy can likely be attributed to attentional distraction. Participants viewed videos of a trained mixed martial artist kicking that included, or did not include, a simulated grunt. The task was to determine as quickly as possible whether the kick was traveling upward or downward. Overall, and replicating the tennis finding, the present results indicate that a participant's response to a kick was delayed and more error prone when a simulated grunt was present. CONCLUSIONS/SIGNIFICANCE: The present findings indicate that simulated grunting may distract an opponent, leading to slower and more error prone responses. The implications for martial arts in particular, and the broader question of whether grunting should be perceived as 'cheating' in sports, are examined.

Auditory Stimulus Detection Partially Depends on Visuospatial Attentional Resources.

Humans' ability to detect relevant sensory information while being engaged in a demanding task is crucial in daily life. Yet, limited attentional resources restrict information processing. To date, it is still debated whether there are distinct pools of attentional resources for each sensory modality and to what extent the process of multisensory integration is dependent on attentional resources. We addressed these two questions using a dual task paradigm. Specifically, participants performed a multiple object tracking task and a detection task either separately or simultaneously. In the detection task, participants were required to detect visual, auditory, or audiovisual stimuli at varying stimulus intensities that were adjusted using a staircase procedure. We found that tasks significantly interfered. However, the interference was about 50% lower when tasks were performed in separate sensory modalities than in the same sensory modality, suggesting that attentional resources are partly shared. Moreover, we found that perceptual sensitivities were significantly improved for audiovisual stimuli relative to unisensory stimuli regardless of whether attentional resources were diverted to the multiple object tracking task or not. Overall, the present study supports the view that attentional resource allocation in multisensory processing is task-dependent and suggests that multisensory benefits are not dependent on attentional resources.

Differential Processing for Actively Ignored Pictures and Words.

Previous work suggests that, when attended, pictures may be processed more readily than words. The current study extends this research to assess potential differences in processing between these stimulus types when they are actively ignored. In a dual-task paradigm, facilitated recognition for previously ignored words was found provided that they appeared frequently with an attended target. When adapting the same paradigm here, previously unattended pictures were recognized at high rates regardless of how they were paired with items during the primary task, whereas unattended words were later recognized at higher rates only if they had previously been aligned with primary task targets. Implicit learning effects obtained by aligning unattended items with attended task-targets may apply only to conceptually abstract stimulus types, such as words. Pictures, on the other hand, may maintain direct access to semantic information, and are therefore processed more readily than words, even when being actively ignored.

Existence of competing modality dominances.

Approximately 40 years of research on modality dominance has shown that humans are inclined to focus on visual information when presented with compounded visual and auditory stimuli. The current paper reports a series of experiments showing evidence of both auditory and visual dominance effects. Using a behavioral oddball task, we found auditory dominance when examining response times to auditory and visual oddballs-simultaneously presenting pictures and sounds slowed down responses to visual but not auditory oddballs. However, when requiring participants to make separate responses for auditory, visual, and bimodal oddballs, auditory dominance was eliminated with a reversal to visual dominance (Experiment 2). Experiment 3 replicated auditory dominance and showed that increased task demands and asking participants to analyze cross-modal stimuli conjunctively (as opposed to disjunctively) cannot account for the reversal to visual dominance. Mechanisms underlying sensory dominance and factors that may modulate sensory dominance are discussed.

A test of motor skill-specific action embodiment in ice-hockey players.

To further our understanding of the role of the motor system in comprehending action-related sentences, we compared action experts (athletes) to visual experts (fans) and novices when responding with an action-specific effector (either hand or foot). These conditions allowed inferences about the degree and specificity of embodiment in language comprehension. Ice hockey players, fans and novices made speeded judgments regarding the congruence between an auditorily presented sentence and a subsequently presented picture. Picture stimuli consisted of either hockey or everyday items. Half of these pictures 'matched' the action implied in the preceding sentence. Further, the action in these images involved either primarily the hand or the foot. For everyday items, action-matched items were responded to faster than action-mismatched items. However, only the players and fans showed the action-match effect for hockey items. There were no consistent effector-stimuli compatibility effects, nor skill-based interactions with compatibility, suggesting that the action-match effect was not based on motor ability per se, but rather a construction of the action based on knowledge or visual experience with the hockey related sentences.

Innocent until primed: mock jurors' racially biased response to the presumption of innocence.

BACKGROUND: Research has shown that crime concepts can activate attentional bias to Black faces. This study investigates the possibility that some legal concepts hold similar implicit racial cues. Presumption of innocence instructions, a core legal principle specifically designed to eliminate bias, may instead serve as an implicit racial cue resulting in attentional bias. METHODOLOGY/PRINCIPAL FINDINGS: The experiment was conducted in a courtroom with participants seated in the jury box. Participants first watched a video of a federal judge reading jury instructions that contained presumption of innocence instructions, or matched length alternative instructions. Immediately following this video a dot-probe task was administered to assess the priming effect of the jury instructions. Presumption of innocence instructions, but not the alternative instructions, led to significantly faster response times to Black faces when compared with White faces. CONCLUSIONS/SIGNIFICANCE: These findings suggest that the core principle designed to ensure fairness in the legal system actually primes attention for Black faces, indicating that this supposedly fundamental protection could trigger racial stereotypes.

The interaction of feature and space based orienting within the attention set.

The processing of sensory information relies on interacting mechanisms of sustained attention and attentional capture, both of which operate in space and on object features. While evidence indicates that exogenous attentional capture, a mechanism previously understood to be automatic, can be eliminated while concurrently performing a demanding task, we reframe this phenomenon within the theoretical framework of the "attention set" (Most et al., 2005). Consequently, the specific prediction that cuing effects should reappear when feature dimensions of the cue overlap with those in the attention set (i.e., elements of the demanding task) was empirically tested and confirmed using a dual-task paradigm involving both sustained attention and attentional capture, adapted from Santangelo et al. (2007). Participants were required to either detect a centrally presented target presented in a stream of distractors (the primary task), or respond to a spatially cued target (the secondary task). Importantly, the spatial cue could either share features with the target in the centrally presented primary task, or not share any features. Overall, the findings supported the attention set hypothesis showing that a spatial cuing effect was only observed when the peripheral cue shared a feature with objects that were already in the attention set (i.e., the primary task). However, this finding was accompanied by differential attentional orienting dependent on the different types of objects within the attention set, with feature-based orienting occurring for target-related objects, and additional spatial-based orienting for distractor-related objects.

A window of perception when diverting attention? Enhancing recognition for explicitly presented, unattended, and irrelevant stimuli by target alignment.

Research has demonstrated that irrelevant suprathreshold motion stimuli that are aligned with attended targets in a separate task, fail to illicit inhibitory control in a subsequent motion direction discrimination task (Tsushima, Seitz, & Watanabe, 2008). We extended these findings to conditions involving higher exposure levels to a more salient stimulus (written words) in an inattentional blindness paradigm. Across three experiments, participants were required to respond to immediate picture repetitions in a stream of serially presented line drawings, while at the same time ignore a simultaneously presented stream of superimposed words. Immediately following, a surprise test was given that measured recognition for the unattended words. Words that had appeared simultaneously with a repeated picture in the repetition detection task were not inhibited, but instead recognized significantly more often than words that had appeared with nonrepeating pictures. These findings support the notion that when attention is taxed, recognition for target-aligned task-irrelevant semantic items can be enhanced in a subsequent recognition task. This indicates a learning effect for frequently exposed, high-level irrelevant-stimuli that were temporally aligned with a relevant item in a separate task.

Reversing the Colavita visual dominance effect.

Many researchers have taken the Colavita effect to represent a paradigm case of visual dominance. Broadly defined, the effect occurs when people fail to respond to an auditory target if they also have to respond to a visual target presented at the same time. Previous studies have revealed the remarkable resilience of this effect to various manipulations. In fact, a reversal of the Colavita visual dominance effect (i.e., auditory dominance) has never been reported. Here, we present a series of experiments designed to investigate whether it is possible to reverse the Colavita effect when the target stimuli consist of repetitions embedded in simultaneously presented auditory and visual streams of stimuli. In line with previous findings, the Colavita effect was still observed for an immediate repetition task, but when an n-1 repetition detection task was used, a reversal of visual dominance was demonstrated. These results suggest that masking from intervening stimuli between n-1 repetition targets was responsible for the elimination and reversal of the Colavita visual dominance effect. They further suggest that varying the presence of a mask (pattern, conceptual, or absent) in the repetition detection task gives rise to different patterns of sensory dominance (i.e., visual dominance, an elimination of the Colavita effect, or even auditory dominance).

Conditions of directed attention inhibit recognition performance for explicitly presented target-aligned irrelevant stimuli.

The fate of irrelevant and overtly presented stimuli that was temporally aligned with an attended target in a separate task was explored. Seitz and Watanabe (2003) demonstrated that if an irrelevant motion stimulus was implicit (i.e., subthreshold), a later facilitation for the same motion direction was observed if the previously presented implicit motion (of the same direction) was temporally aligned with the presence of an attended target. Later research, however, demonstrated that if the motion stimulus aligned with the attended target was explicit (i.e., suprathreshold), a later inhibition was observed (Tsushima, Seitz, & Watanabe, 2008). The current study expands on this by using more salient stimuli (words and pictures) in an inattentional blindness paradigm, and suggests that when attention is depleted, recognition for target-aligned task-irrelevant items is impaired in a subsequent recognition task. Participants were required to respond to either immediate picture, or word, repetitions in a stream of simultaneously presented line drawings and written words, and later given a surprise recognition test that measured recognition for the words or the pictures. When analyzing word recognition performance after attention had been directed to the pictures, words that had appeared simultaneously with a picture repetition in the repetition detection task were recognized at levels significantly below chance. The same inhibition was mirrored when testing for picture recognition after having attended to the words in the repetition detection task. These data suggest an inhibitory mechanism that is exhibited in later recognition tests for salient information that was previously unattended and had been simultaneously being presented with an attended target in a different task.