Task-irrelevant sounds influence both temporal order and apparent-motion judgments about tactile stimuli applied to crossed and uncrossed hands

It has been suggested that judgments about the temporal–spatial order of successive tactile stimuli depend on the perceived direction of apparent motion between them. Here we manipulated tactile apparent-motion percepts by presenting a brief, task-irrelevant auditory stimulus temporally in-between pairs of tactile stimuli. The tactile stimuli were applied one to each hand, with varying stimulus onset asynchronies (SOAs). Participants reported the location of the first stimulus (temporal order judgments: TOJs) while adopting both crossed and uncrossed hand postures, so we could scrutinize skin-based, anatomical, and external reference frames. With crossed hands, the sound improved TOJ performance at short (≤300 ms) and at long (>300 ms) SOAs. When the hands were uncrossed, the sound induced a decrease in TOJ performance, but only at short SOAs. A second experiment confirmed that the auditory stimulus indeed modulated tactile apparent motion perception under these conditions. Perceived apparent motion directions were more ambiguous with crossed than with uncrossed hands, probably indicating competing spatial codes in the crossed posture. However, irrespective of posture, the additional sound tended to impair potentially anatomically coded motion direction discrimination at a short SOA of 80 ms, but it significantly enhanced externally coded apparent motion perception at a long SOA of 500 ms. Anatomically coded motion signals imply incorrect TOJ responses with crossed hands, but correct responses when the hands are uncrossed; externally coded motion signals always point toward the correct TOJ response. Thus, taken together, these results suggest that apparent-motion signals are likely taken into account when tactile temporal–spatial information is reconstructed.

     

The temporal representation of in-phase and anti-phase movements

We have proposed that the stability of bimanual coordination is influenced by the complexity of the representation of the task goals. Here, we present two experiments to explore this hypothesis. First, we examined whether a temporal event structure is present in continuous movements by having participants vocalize while producing bimanual circling movements. Participants tended to vocalize once per movement cycle when moving in-phase. In contrast, vocalizations were not synchronized with anti-phase movements. While the in-phase result is unexpected, the latter would suggest anti-phase continuous movements lack an event structure. Second, we examined the event structure of movements marked by salient turn-around points. Participants made bimanual wrist flexion movements and were instructed to move 'in synchrony' with a metronome, without specifying how they should couple the movements to the metronome. During in-phase movements, participants synchronized one hand cycle with every metronome beat; during anti-phase movements, participants synchronized flexion of one hand with one metronome beat and extension of the other hand with the next beat. The results are consistent with the hypothesis that the instability of anti-phase movements is related to their more complex (or absent) event representation relative to that associated with in-phase movements.     

Task effects on tactile temporal order judgments: when space does and does not matter

The ability to report the temporal order of 2 tactile stimuli (1 applied to each hand) has been shown to decline when the arms are crossed over compared with when they are uncrossed. However, these effects have only been measured when temporal order was reported by stimulus location. It is unknown whether this spatial manipulation of the body affects all tactile temporal order judgments (TOJs) or only those judgments that are spatially defined. The authors examined the effect of crossing the arms on tactile TOJs when stimuli were identified by either spatial (location) or nonspatial (frequency or duration) attributes. Spatial TOJs were significantly impaired when the arms were in crossed compared with uncrossed postures, but there was no effect of posture when order was judged by nonspatial attributes. Task-dependent modulation of the effects of posture was also evident when response complexity was reduced to go/no-go responses. These results suggest that crossing the arms impairs tactile localization and thus spatial TOJs. However, the data also suggest that localization is not a necessary precursor when temporal order can be computed by nonspatial means.     

Imagined and actual limb selection: a test of preference

Imagined and actual motor performance were compared to determine what factor(s) drive limb selection for programming movements in contralateral hemispace. Forty right-handed blindfolded subjects were asked to 'reach' via auditory stimulus for a small object placed at multiple locations in hemispace. Two conditions were included: arms uncrossed and arms crossed. With the uncrossed condition, responses were similar. With arms crossed, subjects had the choice of keeping the limbs crossed, reacting to proximity, or uncrossing the arms to reach ipsilaterally. In this condition subjects 'imagined' that they would maintain the crossedposition and reach with the hand closest to the stimulus in both right and left hemispace. However, during 'actual' reaching, responses differed. For left-field stimuli, participants kept the arms crossed, but in response to right-field stimuli, subjects preferred to uncross the limbs in order to reach with the dominant hand. These findings suggest that while motor dominance is the primary factor in limb choice for action in ipsilateral hemispace, it appears that object proximity drives limb selection for reaching in contralateral hemispace.     

Do working memory-driven attention shifts speed up visual awareness?

Previous research has shown that content representations in working memory (WM) can bias attention in favor of matching stimuli in the scene. Using a visual prior-entry procedure, we here investigate whether such WM-driven attention shifts can speed up the conscious awareness of memory-matching relative to memory-mismatching stimuli. Participants were asked to hold a color cue in WM and to subsequently perform a temporal order judgment (TOJ) task by reporting either of two different-colored circles (presented to the left and right of fixation with a variable temporal interval) as having the first onset. One of the two TOJ circles could match the memory cue in color. We found that awareness of the temporal order of the circle onsets was not affected by the contents of WM, even when participants were explicitly informed that one of the TOJ circles would always match the WM contents. The null effect of WM on TOJs was not due to an inability of the memory-matching item to capture attention, since response times to the target in a follow-up experiment were improved when it appeared at the location of the memory-matching item. The present findings suggest that WM-driven attention shifts cannot accelerate phenomenal awareness of matching stimuli in the visual field.     

Temporal order judgment criteria are affected by synchrony judgment sensitivity

Synchrony perception for audio-visual stimulus pairs is typically studied by using temporal order judgment (TOJ) or synchrony judgment (SJ) tasks. Research has shown that estimates of the point of subjective simultaneity (PSS) obtained using these two methods do not necessarily correspond. Here, we investigate the hypothesis that the PSS estimate obtained in a TOJ task is shifted in the direction of the most sensitive part of the synchrony judgment curve, as obtained in an SJ task. The results confirm that criterion shifts in the TOJ task move the PSS toward regions of the audio-visual temporal interval continuum where discriminations are most sensitive.     

触觉时序知觉手臂交叉效应的性别差异

本研究探讨触觉时序知觉的手臂交叉效应是否存在性别差异。通过两个实验在较短和较长的SOA条件下考察男性和女性被试在基于体觉和基于外部空间的触觉时序判断任务中的表现。结果表明,男性与女性被试在基于体觉和基于外部空间的触觉时序判断任务中均存在手臂交叉效应,SOA较短时男性被试的手臂交叉效应显著小于女性被试,但在SOA较长的条件下手臂交叉效应没有明显的性别差异。触觉时序知觉手臂交叉效应的性别差异可能与空间知觉能力和生理解剖学因素有关。     

Increased visual bias in children with developmental coordination disorder: Evidence from a visual-tactile temporal order judgment task

BackgroundPrevious studies have suggested that children with developmental coordination disorder (DCD) rely heavily on vision to perform movements, which may contribute to their clumsy movements. However, few studies have objectively and quantitatively investigated the perceptual biases of children with DCD.MethodsA visual-tactile temporal order judgment (TOJ) task was used to measure and compare the perceptual biases of 19 children with DCD and 19 age- and sex-matched typically developing children. The point of subjective equality, which demonstrates when “visual first” and “tactile first” judgment probabilities are equal (50%), obtained by analyzing the results of the visual-tactile TOJ task, was used as an indicator of perceptual biases. Further, variables (age and manual dexterity in all participants; motor function, autism spectrum disorder and attention-deficit hyperactivity disorder traits, and depressive symptoms in children with DCD) associated with perceptual biases were examined with correlation analysis.ResultsChildren with DCD had significantly stronger visual bias than typically developing children. Overall correlation analysis showed that increased visual bias was significantly correlated with poor manual dexterity.ConclusionChildren with DCD had a strong visual bias, which was associated with poor manual dexterity.     

Anticipatory Planning of Sequential Hand and Finger Movements

ABSTRACT

Hand movements may be anticipatorily planned to reach an immediate target and at the same time facilitate movements to subsequent targets. Researchers have proposed that in anticipatory planning, information about subsequent targets needs to be processed to engage in the planning of the next movement. To test this hypothesis, the authors varied the information 48 participants had about to-be-executed two-step hand and finger movement sequences prior to a choice reaction signal. Movements were initialized faster if participants had advance information about the second target of the sequence than if participants had no advance information at all. The results imply that movement segments to late targets in a movement sequence may be at least partially planned, even if information about earlier targets is not yet available.     

Arm position influences the activation patterns of trunk muscles during trunk range-of-motion movements

To understand the activation patterns of the trunk musculature, it is also important to consider the implications of adjacent structures such as the upper limbs, and the muscles that act to move the arms. This study investigated the effects of arm positions on the activation patterns and co-activation of the trunk musculature and muscles that move the arm during trunk range-of-motion movements (maximum trunk axial twist, flexion, and lateral bend). Fifteen males and fifteen females, asymptomatic for low back pain, performed maximum trunk range-of-motion movements, with three arm positions for axial twist (loose, crossed, abducted) and two positions for flexion and lateral bend (loose, crossed). Electromyographical data were collected for eight muscles bilaterally, and activation signals were cross-correlated between trunk muscles and the muscles that move the arms (upper trapezius, latissimus dorsi). Results revealed consistently greater muscle co-activation (higher cross-correlation coefficients) between the trunk muscles and upper trapezius for the abducted arm position during maximum trunk axial twist, while results for the latissimus dorsi-trunk pairings were more dependent on the specific trunk muscles (either abdominal or back) and latissimus dorsi muscle (either right or left side), as well as the range-of-motion movement. The findings of this study contribute to the understanding of interactions between the upper limbs and trunk, and highlight the influence of arm positions on the trunk musculature. In addition, the comparison of the present results to those of individuals with back or shoulder conditions may ultimately aid in elucidating underlying mechanisms or contributing factors to those conditions.     

Planning of reach-and-grasp movements: effects of validity and type of object information

Individuals are assumed to plan reach-and-grasp movements by using two separate processes. In 1 of the processes, extrinsic (direction, distance) object information is used in planning the movement of the arm that transports the hand to the target location (transport planning); whereas in the other, intrinsic (shape) object information is used in planning the preshaping of the hand and the grasping of the target object (manipulation planning). In 2 experiments, the authors used primes to provide information to participants (N = 5, Experiment 1; N = 6, Experiment 2) about extrinsic and intrinsic object properties. The validity of the prime information was systematically varied. The primes were succeeded by a cue, which always correctly identified the location and shape of the target object. Reaction times were recorded. Four models of transport and manipulation planning were tested. The only model that was consistent with the data was 1 in which arm transport and object manipulation planning were postulated to be independent processes that operate partially in parallel. The authors suggest that the processes involved in motor planning before execution are primarily concerned with the geometric aspects of the upcoming movement but not with the temporal details of its execution.     

Separate movement planning and spatial assimilation effects in sequential bimanual aiming movements

This study extended earlier work by showing spatial assimilations in sequential bimanual aiming movements when the participant preplanned only the first movement of a two-movement sequence. Right-handed participants (n=20, aged 18 to 22 years) made rapid lever reversals of 20 degrees and 60 degrees singly and sequentially with an intermovement interval of 2.5 sec. Following blocked single practice of both movements in each hand (15 trials each), two sets of 30 sequential practice trials were completed. The sequences began with either the long or the short movement and the participant always knew the goal of the first movement. During the intermovement interval, the experimenter gave instructions to complete the sequence with a short movement, a long movement, or no movement in a random order. Compared to the single trials, both movements in the sequence overshot the short-distance and undershot the long-distance goal. Spatial errors increased when a change in the movement goal was required for the second movement in the sequence. The experiment demonstrated that separate planning of sequential aiming movements can reduce spatial assimilation effects, but interference due to practice organization and switching the task's goal must also be overcome in order to produce accurate aiming movements.     

Target- and effect-directed actions towards temporal goals: Similar mechanisms?

The goal of an action can consist of generating a change in the environment (to produce an effect) or changing one's own situation in the environment (to move to a physical target). To investigate whether the mechanisms of effect-directed and target-directed action control are similar, participants performed continuous reversal movements. They either synchronized movement reversals with regularly presented tones (temporal targets) or produced tones at reversals isochronously (temporal effects). In both goal conditions an irrelevant goal characteristic was integrated into the goal representation (loudness, Experiment 1). When targets and effects were presented within the same reversal movement, similarities were enhanced (Experiment 2). When the task posed spatial demands in addition to temporal demands, target- and effect-directed movement kinematics changed equally with tempo (Experiment 3). Correlations between target-directed and effect-directed movements in temporal variability indicated similar timing mechanisms (Experiments 1 and 2). Only gradual differences between target- and effect-directed movements were observed. We conclude that the same mechanisms of action control, including the anticipation of upcoming events, underlie effect-directed and target-directed movements. Ideomotor theories of action control should incorporate action targets as goals similar to action effects. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Change of reference frame for tactile localization during child development

Temporal order judgements (TOJ) for two tactile stimuli, one presented to the left and one to the right hand, are less precise when the hands are crossed over the midline than when the hands are uncrossed. This ‘crossed hand’ effect has been considered as evidence for a remapping of tactile input into an external reference frame. Since late, but not early, blind individuals show such remapping, it has been hypothesized that the use of an external reference frame develops during childhood. Five‐ to 10‐year‐old children were therefore tested with the tactile TOJ task, both with uncrossed and crossed hands. Overall performance in the TOJ task improved with age. While children older than 5½ years displayed a crossed hand effect, younger children did not. Therefore the use of an external reference frame for tactile, and possibly multisensory, localization seems to be acquired at age 5.     

Deliberate Control of Continuous Motor Performance

The authors examined the means by which people vary movement parameters to satisfy more than 1 constraint at a time in a repetitive motor task. The authors expected that when participants (N = 12) were simultaneously confronted with spatial and temporal constraints in an ellipse-drawing task, they would either exploit the intrinsic amplitude-frequency relationships or activate less natural control regimes to prioritize their movement goals. By focusing on local amplitude and frequency errors and parameter changes from 1 movement to the next, the authors distinguished parameter changes that reflected exploitation of biomechanics from those that required deliberate control. The findings demonstrated that at low movement speeds, participants can pursue multiple movement goals simultaneously; at higher speeds, their capacity to satisfy multiple task goals is reduced. The authors used a new method of inferring deliberate control from movement kinematics in the present study.     

Self-selected visual information during discrete manual aiming

The authors examined strategic selection of visual samples during manual aiming. Participants (N = 12) wore liquid-crystal goggles while performing discrete movements to a small target. Initially, participants controlled a 40-ms visual sample via a switch in their nonaiming hand. Subsequently, experimenter-imposed strategies required participants to take visual samples before movement initiation or early or late in the movement. Although participants adopted a variety of strategies to optimize the use of vision, they were more likely to select a sample during the early stages of the movement. Experimenter-imposed early and late instructions resulted in longer movement times than did self-selected sampling. Compared with late sampling, early sampling resulted in a temporal advantage with similar accuracy.     

Deliberate control of continuous motor performance

The authors examined the means by which people vary movement parameters to satisfy more than 1 constraint at a time in a repetitive motor task. The authors expected that when participants (N = 12) were simultaneously confronted with spatial and temporal constraints in an ellipse-drawing task, they would either exploit the intrinsic amplitude-frequency relationships or activate less natural control regimes to prioritize their movement goals. By focusing on local amplitude and frequency errors and parameter changes from 1 movement to the next, the authors distinguished parameter changes that reflected exploitation of biomechanics from those that required deliberate control. The findings demonstrated that at low movement speeds, participants can pursue multiple movement goals simultaneously; at higher speeds, their capacity to satisfy multiple task goals is reduced. The authors used a new method of inferring deliberate control from movement kinematics in the present study.     

Attentional bias toward low-intensity stimuli: an explanation for the intensity dissociation between reaction time and temporal order judgment?

If two stimuli need different times to be processed, this difference should in principle be reflected both by response times (RT) and by judgments of their temporal order (TOJ). However, several dissociations have been reported between RT and TOJ, e.g., RT is more affected than TOJ when stimulus intensity decreases. One account for these dissociations is to assume differences in the allocation of attention induced by the two tasks. To test this hypothesis, different distributions of attention were induced in the present study between two stimulus positions (above and below fixation). Only bright stimuli appeared in one position and either bright or dim stimuli in the other. In the two RT experiments, participants had to respond to every stimulus appearing in one of the two positions. Reaction times to bright stimuli were faster when they appeared in the position where dim stimuli were likely to occur. This finding suggests that the allocation of attention was adapted to the asymmetrical arrangement of stimuli, not suggested by explicit instruction. In the two TOJ experiments, the temporal order of stimuli appearing in the two positions had to be judged. Although bright stimuli appearing at the bright-and-dim location were judged to be earlier, this effect was small and insignificant. Further, the intensity dissociation between RT and TOJ was insensitive to random vs blockwise presentations of intensities, therefore was not modified by attentional preferences. Thus, asymmetrical arrangement of stimuli has an impact on the allocation of attention, but only in the RT task. Therefore dissociations between TOJ and response times cannot be accounted for by an attentional bias in the TOJ task but probably by different use of temporal information in the two tasks.     

Self-Selected Visual Information During Discrete Manual Aiming

The authors examined strategic selection of visual samples during manual aiming. Participants (N = 12) wore liquid-crystal goggles while performing discrete movements to a small target. Initially, participants controlled a 40-ms visual sample via a switch in their nonaiming hand. Subsequently, experimenter-imposed strategies required participants to take visual samples before movement initiation or early or late in the movement. Although participants adopted a variety of strategies to optimize the use of vision, they were more likely to select a sample during the early stages of the movement. Experimenter-imposed early and late instructions resulted in longer movement times than did self-selected sampling. Compared with late sampling, early sampling resulted in a temporal advantage with similar accuracy.     

The trajectory effect in intermodal temporal order judgments

Subjects judged which one of two patterns, a visual or a tactile pattern, had been presented first. The visual and tactile displays were placed in close spatial proximity. The patterns appeared to move across their respective displays. Although irrelevant to the temporal order judgment (TOJ), the direction of motion of the patterns--the trajectory--affected the judgments. When the leading pattern was moving towards the trailing pattern (consistent movement), subjects tended to judge it, correctly, as leading. When the leading pattern was moving away from the trailing pattern (inconsistent movement), subjects tended to judge it, incorrectly, as trailing. Changing the spatial position of the arrays such that the pattern trajectories were no longer towards one another eliminated the effect of movement on TOJs. Although there was a substantial difference in performance on consistent and inconsistent trials, there were no differences in subjects' ratings of their performances. The results demonstrate that the trajectory effect can be obtained multimodally. The issues whether the effect of motion alters the perceived temporal separation between the visual and tactile patterns, and whether the visual and tactile patterns are represented by a common framework, are discussed.