Hand-held Pendulums Research Articles

Moving objects by imagination? Amount of finger movement and pendulum length determine success in the Chevreul pendulum illusion.

Hand-held pendulums can seemingly oscillate on their own, without perceived conscious control. This illusion, named after Chevreul, is likely a result of ideomotor movements. While this phenomenon was originally assumed to have a supernatural basis, it has been accepted for over 150years that the movements are self-generated. However, until now, recordings of the small movements that create these oscillations have not been performed. In this study, we examined how participants produce these unconscious oscillations using a motion capture system. As expected, the Chevreul pendulum illusion was produced when the fingers holding the pendulum generated an oscillating frequency close to the resonant frequency of the pendulum, where very small driving movements of the arm are sufficient to produce relatively large pendulum motion. We found that pendulum length significantly affected the ability to produce the illusion - participants were much more successful with a 40cm compared to an 80cm pendulum. Further, we found that participants that tended to move their fingers more were more successful in producing the illusion but did not find a connection between inter-joint coordination and ability to generate the illusion.

Comb-structured triboelectric nanogenerators for multi-directional energy scavenging from human movements

ABSTRACT A triboelectric nanogenerator (TENG) is an emerging energy harvesting technology utilizing multi-directional, wasted mechanical energies stemming from vibrations, winds, waves, body movements, etc. In this study, we report a comb-structured TENG (CTENG) capable of effectively scavenging multi-directional motions from human movements, which include walking, jumping, and running. By attaching CTENG to a person’s calf, we obtain a root-mean-square (RMS) power value of 5.28 μW (i.e. 13.12 V and 0.4 μA) for 1 s during mild running action (~5 m/s), which is sufficient for powering 10 light emitting diodes (LEDs). We integrate a CTENG with a simple hand-held pendulum (HHP) system with a natural frequency of 5.5 Hz. The natural frequency and input energy of our HHP system can be easily controlled by changing the holder mass and initial bending displacement, thus producing different output behaviors for the CTENG. Under the optimal HHP-based CTENG system design, the maximum output reaches 116 V at 6.5 μA under 0.1 kg mass and 4 cm bending displacement conditions. The corresponding output energy is 52.7 μJ for an operation time of 10.8 s. Our HHP-CTENG system can sufficiently power 45 LEDs and shows different output performances by varying the driving velocity of a vehicle, thus demonstrating the possibility for a self-powered velocity monitoring system.

Single (1:1) vs. double (1:2) metronomes for the spontaneous entrainment and stabilisation of human rhythmic movements.

Rhythmic movements produced by humans become spontaneously entrained to auditory rhythms in the environment. Evidence suggests that synchronisation to external auditory rhythms can contribute to the stabilisation of movements in time and space, opening new perspectives for motor training and rehabilitation. Here we compared the effects of single (1:1) and double (1:2) metronomes (i.e., one or two stimulations per preferred movement cycle) on spontaneous movement entrainment and stabilisation. We examined the spontaneous entrainment of self-paced hand-held pendulum swinging when single or double metronomes were presented either at the participant's preferred tempo or slightly slower or faster (± 10%). The results showed that participants' movements spontaneously entrained to auditory rhythms, and that the strength of this entrainment was the same for single and double metronomes. However, double metronomes decreased movement tempo stability, whereas single metronomes increased movement tempo stability compared to a control condition without a stimulus. These effects preferentially occurred for metronomes presented at participants' preferred movement tempi and especially for participants whose movements were intrinsically more variable. Participants' movement amplitude stability was also modulated in such a way that the stability of participants who were intrinsically less stable increased, whereas the stability of intrinsically more stable participants decreased with auditory rhythms, an effect that was stronger with double than single metronomes. Moreover, movement stabilisation in time and space were positively correlated, suggesting that tempo and amplitude stabilisation depend on similar processes and may be complementary. These findings provide new insight into the processes underlying auditory-motor entrainment and how auditory rhythms can be used to improve movement stability in time and space.

Effects of pitch and tempo of auditory rhythms on spontaneous movement entrainment and stabilisation.

Human movements spontaneously entrain to auditory rhythms, which can help to stabilise movements in time and space. The properties of auditory rhythms supporting the occurrence of this phenomenon, however, remain largely unclear. Here, we investigate in two experiments the effects of pitch and tempo on spontaneous movement entrainment and stabilisation. We examined spontaneous entrainment of hand-held pendulum swinging in time with low-pitched (100Hz) and high-pitched (1600Hz) metronomes to test whether low pitch favours movement entrainment and stabilisation. To investigate whether stimulation and movement tempi moderate these effects of pitch, we manipulated (1) participants' preferred movement tempo by varying pendulum mechanical constraints (Experiment 1) and (2) stimulation tempo, which was either equal to, or slightly slower or faster (± 10%) than the participant's preferred movement tempo (Experiment 2). The results showed that participants' movements spontaneously entrained to auditory rhythms, and that this effect was stronger with low-pitched rhythms independently of stimulation and movement tempi. Results also indicated that auditory rhythms can lead to increased movement amplitude and stabilisation of movement tempo and amplitude, particularly when low-pitched. However, stabilisation effects were found to depend on intrinsic movement variability. Auditory rhythms decreased movement variability of individuals with higher intrinsic variability but increased movement variability of individuals with lower intrinsic variability. These findings provide new insights into factors that influence auditory-motor entrainment and how they may be optimised to enhance movement efficiency.

Getting into the Swing of things: An investigation into rhythmic unimanual coordination in typically developing children

Unimanual coordination is a vital component of everyday life and underpins successful engagement of many activities of daily living and physical activity participation. The ability to coordinate with environmental stimuli has been extensively studied in adults in a variety of situations. However, we know little about these processes in children and even less about how these processes change as age increases. This paper examines children’s performance in a rhythmic unimanual coordination task using a handheld pendulum. Participants (aged 6, 9 and 11 years) manipulated the pendulum at 3 frequencies (preferred frequency, +20% of preferred and −20% of preferred frequency) in coordination with 3 stimuli (Visual, Auditory and Visual-Auditory combined). Results showed that children’s coordination levels and movement variability improved with age, however still fell below those observed in adults. In addition children demonstrated preferences for visual stimuli or multisensory stimuli compared to auditory stimuli on their own Interestingly, children were found to demonstrate different movement amplitudes for −20%, preferred and +20% frequency conditions. In conclusion, children’s unimanual coordination levels were found to follow the typical maturation process and improve with age. Further to this, findings suggest the potential benefit of multisensory information for uni manual coordination in children.

Investigation of the effects of transcranial alternating current stimulation (tACS) on self-paced rhythmic movements

Human rhythmic movements spontaneously entrain to external rhythmic stimuli. Such sensory-motor entrainment can attract movements to different tempi and enhance their efficiency, with potential clinical applications for motor rehabilitation. Here we investigate whether entrainment of self-paced rhythmic movements can be induced via transcranial alternating current stimulation (tACS), which uses alternating currents to entrain spontaneous brain oscillations at specific frequencies. Participants swung a handheld pendulum at their preferred tempo with the right hand while tACS was applied over their left or right primary motor cortex at frequencies equal to their preferred tempo (Experiment 1) or in the alpha (10Hz) and beta (20Hz) ranges (Experiment 2). Given that entrainment generally occurs only if the frequency difference between two rhythms is small, stimulations were delivered at frequencies equal to participants’ preferred movement tempo (≈1Hz) and ±12.5% in Experiment 1, and at 10Hz and 20Hz, and ±12.5% in Experiment 2. The comparison of participants’ movement frequency, amplitude, variability, and phase synchrony with and without tACS failed to reveal entrainment or movement modifications across the two experiments. However, significant differences in stimulation-related side effects reported by participants were found between the two experiments, with phosphenes and burning sensations principally occurring in Experiment 2, and metallic tastes reported marginally more often in Experiment 1. Although other stimulation protocols may be effective, our results suggest that rhythmic movements such as pendulum swinging or locomotion that are low in goal-directedness and/or strongly driven by peripheral and mechanical constraints may not be susceptible to modulation by tACS.

Ask the pendulum: personality predictors of ideomotor performance.

For centuries, people have asked questions to hand-held pendulums and interpreted their movements as responses from the divine. These movements occur due to the ideomotor effect, wherein priming or thinking of a motion causes muscle movements that end up swinging the pendulum. By associating particular swinging movements with “yes” and “no” responses, we investigated whether pendulums can aid decision-making and which personality traits correlate with this performance. Participants () completed a visual detection task in which they searched for a target letter among rapidly presented characters. In the verbal condition, participants stated whether they saw the target in each trial. In the pendulum condition, participants instead mentally “asked” a hand-held pendulum whether the target was present; particular motions signified “yes” and “no”. We measured the accuracy of their responses as well as their sensitivity and bias using signal detection theory. We also assessed four personality measures: locus of control (feelings of control over one’s life), transliminality (sensitivity to subtle stimuli), need for cognition (preference for analytical thinking), and faith in intuition (preference for intuitive thinking). Overall, locus of control predicted verbal performance and transliminality predicted pendulum performance. Accuracy was low in both conditions (verbal: 57%, pendulum: 53%), but bias was higher in the verbal condition (). We confirmed this bias difference in a second study (, ). Our results suggest that people have different decision strategies when using a pendulum compared to conscious guessing. These findings may help explain why some people can answer questions more accurately with pendulums and Ouija boards. More broadly, identifying the differences between ideomotor and verbal responses could lead to practical ways to improve decision-making.

Social Motor Coordination in Schizophrenia Patients: From Impairment to Rehabilitation

Introduction Motor coordination of interacting people influences social cognitive functioning, impacting feelings of connectedness or interpersonal rapport and communication. Social interaction deficits are one of the most significant and defining features of schizophrenia but until recently no quantitative and objective measures of social motor coordination in schizophrenia have been proposed. Objectives We aimed to investigate social motor coordination of patients suffering from schizophrenia and the implication of this paradigm in rehabilitation, using priming effects. Methods Interpersonal coordination was assessed with a hand-held pendulum task. In the first experiment we evaluated intentional social motor coordination in 20 schizophrenia patients and 20 healthy controls. In the second experiment, hand-held pendulum task was realized after implicit exposure to pro-social, non-social or anti-social primes, in 45 patients and 45 healthy controls. Results We found that intentional social motor coordination was impaired in patient suffering from schizophrenia with lower stability and the fact that patients never led the coordination. In the second experiment, we found that schizophrenia patients who received pro-social priming have greater stability during interpersonal coordination. Furthermore, pro-social priming induced, in their synchronization partner greater feelings of connectedness towards patients. Conclusion First we demonstrate that schizophrenic patients have a specific relational motor signature. Such findings may lead to the development of rehabilitation protocols improving social motor coordination and successful social exchanges of patients. This hypothesis is strengthened by the fact that pro-social priming can have a direct and important effect on improving social motor interaction in patients suffering from schizophrenia.

The supplementation of spatial information improves coordination

Vision plays an important role in allowing the development of coordinated movements and often acts as the dominant perceptual modality for every day movements. This visual information is often presented in the spatio-temporal domain but the specific role of spatio-temporal information has not been specifically assessed in the literature. This experiment used two visual stimuli to assess the reliance on spatio-temporal integration and the effect of supplementing spatial information to a temporal stimulus on coordination. Participants manipulated a hand held pendulum at three frequencies in coordination with these stimuli. The results revealed that the supplementation of spatial information significantly improved coordination. Interestingly, the absence of spatial information still produced good levels of coordination indicating a resilience of motor coordination to adapt to changes in the environment.

Social Motor Coordination in Unaffected Relatives of Schizophrenia Patients: A Potential Intermediate Phenotype

Intermediate endophenotypes emerge as an important concept in the study of schizophrenia. Although research on phenotypes mainly investigated cognitive, metabolic or neurophysiological markers so far, some authors also examined the motor behavior anomalies as a potential trait-marker of the disease. However, no research has investigated social motor coordination despite the possible importance of its anomalies in schizophrenia. The aim of this study was thus to determine whether coordination modifications previously demonstrated in schizophrenia are trait-markers that might be associated with the risk for this pathology. Interpersonal motor coordination in 27 unaffected first-degree relatives of schizophrenia patients and 27 healthy controls was assessed using a hand-held pendulum task to examine the presence of interpersonal coordination impairments in individuals at risk for the disorder. Measures of neurologic soft signs, clinical variables and neurocognitive functions were collected to assess the cognitive and clinical correlates of social coordination impairments in at-risk relatives. After controlling for potential confounding variables, unaffected relatives of schizophrenia patients had impaired intentional interpersonal coordination compared to healthy controls while unintentional interpersonal coordination was preserved. More specifically, in intentional coordination, the unaffected relatives of schizophrenia patients exhibited coordination patterns that had greater variability and in which relatives did not lead the coordination. These results show that unaffected relatives of schizophrenia patients, like the patients themselves, also present deficits in intentional interpersonal coordination. For the first time, these results suggest that intentional interpersonal coordination impairments might be a potential motor intermediate endophenotype of schizophrenia opening new perspectives for early diagnosis.

1283 – Social motor coordinations: a study with schizophrenia and social phobic patients

Introduction Social interactions dysfunctions make up core symptoms of many mental disorders and have been extensively studied through cognitive paradigms gathered under the concept of social cognition. Nevertheless, a growing body of literature have demonstrated that motor coordination is an important feature of these human social interactions but has been little studied in the context of mental diseases. Objective In this study, we propose to compare the processes of inter-agent coordination in healthy and socially impaired clinical populations (e.g. schizophrenia and social phobia patients). Method 20 schizophrenia and 20 social phobia patients were compared to 20 healthy subjects using an hand-held pendulum paradigm in intentional and unintentional interpersonal motor coordination, with different leadership conditions. All participants had psychopathological and neuropsychological evaluations. Results Our results demonstrated that each group of subject was characterised by specific signature concerning interpersonal motor coordination. More specifically, instability of the coordination and temporal delay between patient and controls revealed that schizophrenia impaired intentional coordination but not spontaneous non-intentional coordination whereas social phobia only affected leader conditions. Conclusion Taken altogether, these preliminary results give evidence that motor control through motor coordination behaviours is a fundamental part of social interactions deficits in schizophrenia and social phobia. These results lead us to examine if the evaluation of motor coordination during a social interactions could help to discriminate the deficits in social interactions and to propose specific therapy for their rehabilitation. Acknowledgements This research was supported by an Agence Nationale de la Recherche grant (Project SCAD # ANR-09- BLAN-0405-03).

Strong anticipation: complexity matching in interpersonal coordination

A subtle coordination occurs within complex systems, between multiple nested sub-systems. This intra-system coordination can be detected by the presence of 1/f fluctuations produced by the system. But coordination can occur also between systems. Interpersonal coordination has been studied from a local point of view until now, focusing on macroscopic interactions. But the recent concept of strong anticipation introduced by Dubois (Lect Notes Comput Sci 2684:110-132, 2003) suggests that interactions could occur on multiple levels between complex systems. The hypothesis is that time series in interpersonal synchronization present a matching of the complexity index (fractal exponent). Moreover, it is argued that this matching is not a consequence of short-term adaptations but reveals a global coordination between participants. Eleven pairs of participants oscillated a hand-held pendulum in the in-phase pattern for 11 min, in three conditions where the coupling strength was manipulated by the perceptual feedbacks. The results show a high correlation between fractal exponents irrespective of the coupling strength, and a very low percentage of local cross-correlations between time series appear at lag 0 and lag 1. These results suggest that interpersonal coordination, and more globally synchronization of participants with natural environments, is based on non-local time scales.

Impairments of Social Motor Coordination in Schizophrenia

It has been demonstrated that motor coordination of interacting people plays a crucial role in the success of social exchanges. Abnormal movements have been reported during interpersonal interactions of patients suffering from schizophrenia and a motor coordination breakdown could explain this social interaction deficit, which is one of the main and earliest features of the illness. Using the dynamical systems framework, the goal of the current study was (i) to investigate whether social motor coordination is impaired in schizophrenia and (ii) to determine the underlying perceptual or cognitive processes that may be affected. We examined intentional and unintentional social motor coordination in participants oscillating hand-held pendulums from the wrist. The control group consisted of twenty healthy participant pairs while the experimental group consisted of twenty participant pairs that included one participant suffering from schizophrenia. The results showed that unintentional social motor coordination was preserved while intentional social motor coordination was impaired. In intentional coordination, the schizophrenia group displayed coordination patterns that had lower stability and in which the patient never led the coordination. A coupled oscillator model suggests that the schizophrenia group coordination pattern was due to a decrease in the amount of available information together with a delay in information transmission. Our study thus identified relational motor signatures of schizophrenia and opens new perspectives for detecting the illness and improving social interactions of patients.

The role of haptic information in shaping coordination dynamics: Inertial frame of reference hypothesis

Current research suggests that non-visual perception of the spatial orientation of body segments is tied to vectors representative of their mass moment distribution (vmm). Our question was whether the relative orientation of vmm of right and left hands (Δvmm=vmm left−vmm right) constitutes haptic information supporting bimanual coordination and, if so, how it contributes to coordination dynamics. Blindfolded participants coordinated the motions of a pair of cross-shaped, hand-held pendulums that were either symmetrically loaded (Δvmm=0) or asymmetrically loaded (Δvmm≠0). The sign and magnitude of Δvmm, in particular of the first moment vector, systematically affected the pattern of coordination (indexed by mean relative phase ϕ), but not its stability. These results suggest that (1) Δvmm specifies a frame of reference about which coordination is organized; and (2) that the changes in pattern were a function of the experimentally induced biases in this perceptual frame of reference and not a function of a functional asymmetry akin to detuning. The implications of the findings to the understanding of perceptual regulation of interlimb coordination were discussed.

Effects of movement stability and congruency on the emergence of spontaneous interpersonal coordination

The current project evaluated the relationship between the stability of intrapersonal coordination and the emergence of spontaneous interpersonal coordination. Participants were organized into pairs, and each participant was instructed to produce either an inphase or antiphase pattern of intrapersonal bimanual coordination using two hand-held pendulums, while simultaneously performing an interpersonal puzzle task. At issue was whether the emergence and stability of spontaneous interpersonal rhythmic coordination is influenced by ("Experiment 1") the stability of the intrapersonal coordination patterns produced by co-actors and ("Experiment 2") the congruency of the intrapersonal coordination patterns produced by co-actors. The stability of intrapersonal movement coordination did not affect the emergence of spontaneous interpersonal coordination. The degree of interpersonal coordination observed was similar when both participants in a pair produced either inphase or antiphase patterns of intrapersonal bimanual coordination. Moreover, the congruency of the intrapersonal coordination patterns only slightly affected the emergence of interpersonal coordination, with only marginally lower inphase interpersonal entrainment when participants produced incongruent patterns of intrapersonal coordination (e.g., inphase-antiphase). Interestingly, movement observation and the emergence of interpersonal coordination did not affect the stability of intrapersonal bimanual coordination. The results suggest that interlimb rhythmic bimanual coordination reflects a single intrapersonal perceptual-motor synergy and that these bimanual synergies (not individual limbs) are what become spontaneously entrained interpersonally.

Ideomotor Signaling: From Divining Spiritual Messages to Discerning Subconscious Answers during Hypnosis and Hypnoanalysis, a Historical Perspective

Ideomotor movements account for non-conscious motions of the hand held pendulum and Ouija board planchette that once were attributed to external spirits. Chevreul and Carpenter in the mid-1800s pioneered our scientific understanding of ideomotor movements. The intention or thought is transmitted to the motor cortex at a subconscious level, coordinated by the cerebellum, and sent down spinal nerves to the appropriate muscles, inducing micromovements not visible to the naked eye but amplified by the hand held pendulum or by the slow ratchet-like cumulative movements of a finger or other body part. This ideomotor phenomenon has been utilized during hypnotic trance to provide nonverbal communication of “yes” or “no” or “I don't want to answer” using finger signals or hand held pendulum. LeCron first used this ideomotor form of communication in conjunction with psychosomatic hypnoanalysis. Cheek expanded and more recently Hammond, Walsh, Ewin and others have refined its use.

Location but not amount of stimulus occlusion influences the stability of visuomotor coordination

The current study examined whether the amount and location of available movement information influenced the stability of visuomotor coordination. Participants coordinated a handheld pendulum with an oscillating visual stimulus in an inphase and antiphase manner. The effects of occluding different amounts of phase at different phase locations were examined. Occluding the 0°/180° phase locations (end-points) significantly increased the variability of the visuomotor coordination. The amount of occlusion had little or no affect on the stability of the coordination. We concluded that the end-points of a visual rhythm are privileged and provide access to movement information that ensures stable coordination. The results are discussed with respect to the proposal of Bingham (Ecol Psychol 16:45–43, 2004) and Wilson et al. (Exp Brain Res 165:351–361, 2005) that the relevant information for rhythmic visual coordination is relative direction information.

Location but not amount of stimulus occlusion influences the stability of visuo-motor coordination

The current study examined whether the amount and location of available movement information influenced the stability of visuo-motor coordination. Participants coordinated a hand-held pendulum with an oscillating visual stimulus in an inphase and antiphase manner. The effects of occluding different amounts of phase at different phase locations were examined. Occluding the 0 degrees /180 degrees phase locations (end-points) significantly increased the variability of the visuo-motor coordination. The amount of occlusion had little or no affect on the stability of the coordination. We concluded that the end-points of a visual rhythm are privileged and provide access to movement information that ensures stable coordination. The results are discussed with respect to the proposal of Bingham and colleagues (e.g., Bingham GP. Ecol Psychol 16:45-53, 2004a; Wilson AD, Collins DR, Bingham GP. Exp Brain Res 165:351-361, 2005a) that the relevant information for rhythmic visual coordination is relative direction information.

Visual–spatial and anatomical constraints interact in a bimanual coordination task with transformed visual feedback

There is a debate in the literature about the influence of spatial and anatomical constraints on bimanual coordination dynamics. In the present experiment, participants swung hand-held pendulums about the wrist while attending to visual feedback about relative phase (superimposed phase plots of each pendulum) that was displayed on a screen. Participants were instructed to maintain in-phase or anti-phase coordination in the visual display. Visual-spatial and anatomical constraints were dissociated by introducing a phase shift in the visual display so that visual feedback differed from the movements being performed by the participants in 15 degrees increments from -180 degrees to +180 degrees. Analysis of mean relative phase and its variability suggested that visual-spatial and anatomical constraints interact in bimanual coordination dynamics.

Comparing the attractor strength of intra- and interpersonal interlimb coordination using cross-recurrence analysis

Previous research has demonstrated that intra- and interpersonal rhythmic interlimb coordination are both constrained by the self-organizing entrainment process of coupled oscillators. Despite intra- and interpersonal coordination exhibiting the same stable macroscopic movement patterns the variability of the coordination is typically found to be much greater for inter- compared to intrapersonal coordination. Researchers have assumed that this is due to the interpersonal visual-motor coupling producing a weaker attractor dynamic than the intrapersonal neuromuscular coupling. To determine whether this assumption is true, two experiments were conducted in which pairs of participants coordinated hand-held pendulums swung about the wrist, either intra- and interpersonally. Using the cross-recurrence statistics of percent recurrence and maxline to independently index the level of noise and the attractor strength of the coordination, respectively, the results confirmed that the attractor strength was significantly weaker for inter- compared to intrapersonal coordination and that a similar magnitude of noise underlies both.