Rhythmic Entrainment Research Articles

Emotions, Mechanisms, and Individual Differences in Music Listening

Emotions have been found to play a paramount role in both everyday music experiences and health applications of music, but the applicability of musical emotions depends on: 1) which emotions music can induce, 2) how it induces them, and 3) how individual differences may be explained. These questions were addressed in a listening test, where 44 participants (aged 19–66 years) reported both felt emotions and subjective impressions of emotion mechanisms (Mec Scale), while listening to 72 pieces of music from 12 genres, selected using a stratified random sampling procedure. The results showed that: 1) positive emotions (e.g., happiness) were more prevalent than negative emotions (e.g., anger); 2) Rhythmic entrainment was the most and Brain stem reflex the least frequent of the mechanisms featured in the BRECVEMA theory; 3) felt emotions could be accurately predicted based on self-reported mechanisms in multiple regression analyses; 4) self-reported mechanisms predicted felt emotions better than did acoustic features; and 5) individual listeners showed partly different emotion-mechanism links across stimuli, which may help to explain individual differences in emotional responses. Implications for future research and applications of musical emotions are discussed.

Assessing Sensorimotor Synchronisation in Toddlers Using the Lookit Online Experiment Platform and Automated Movement Extraction.

Adapting gross motor movement to match the tempo of auditory rhythmic stimulation (sensorimotor synchronisation; SMS) is a complex skill with a long developmental trajectory. Drumming tasks have previously been employed with infants and young children to measure the emergence of rhythmic entrainment, and may provide a tool for identification of those with atypical rhythm perception and production. Here we describe a new protocol for measuring infant rhythmic movement that can be employed at scale. In the current study, 50 two-year-olds drummed along with the audiovisual presentation of four steady rhythms, using videos of isochronous drumming at 400, 500, 600, and 700 ms IOI, and provided their spontaneous motor tempo (SMT) by drumming in silence. Toddlers’ drumming is observed from video recordings made in participants’ own homes, obtained via the Lookit platform for online infant studies. We use OpenPose deep-learning model to generate wireframe estimates of hand and body location for each video. The vertical displacement of the hand was extracted, and the power and frequency of infants’ rhythmic entrainment quantified using Fast Fourier Transforms. We find evidence for age-appropriate tempo-flexibility in our sample. Our results demonstrate the feasibility of a fully digital approach to measuring rhythmic entrainment from within the participant’s home, from early in development.

Sensorimotor synchronization with music and metronome in school-aged children

Sensorimotor synchronization (SMS), the coordination of body movements with external stimuli (e.g., dancing, clapping along with music, sport activities), increases throughout childhood when assessed by finger-tapping (FT) tasks following rhythmic auditory cues using metronomes. However, metronomes may support less rhythmic entrainment than naturalistic auditory cues like music, so they may be less effective in showing developmental improvement. This study investigated the effects of age and sex on SMS comparing metronome versus music stimuli in four auditory FT tasks with regular fast (inter-stimulus interval [ISI] = 333 ms) and slow tempi (ISI = 1,000 ms). Participants were 305 typically developing children aged 6 to 11 years. We found improvement (lower variability) in performance with increasing age irrespective of the metronome or music FT and sex, particularly between 6 and 9 years, after which performance stabilized. Nonetheless, mostly irrespective of age, performance for music and metronome stimuli showed differences in synchronization accuracy and variability, indicating that the type of rhythmic stimuli affects performance. A developmental effect was also found in inter-tap variability (but not inter-tap accuracy). Overall, developmental effects were more robust in FT variability (motor implementation) although responses to music and metronome stimuli differed in ways that may be relevant to SMS deficits in clinical populations.

Individual Differences in Responses to Rhythmic Entrainment in Music and Movement Intervention Among Individuals with Autism

This study examines the influence of individual differences in sensory sensitivities and motor functions of four individuals with a spectrum of autistic traits on impacting their responses to the music and movement intervention. A multiple case study approach examines the participants’ individualised responses to rhythmic entrainment during the six-week music and movement intervention. Sensory sensitivities play a vital role in affecting the four participants entraining their body movements to the rhythmic cues, and inducing their auditory-motor mechanism. The findings indicate that each participant with autism has a distinctive response to the rhythmic cues, and this impacts the treatment outcomes of the music and movement intervention. The study recommends future researchers include individual differences in sensory and motor development as part of their investigation. These factors can directly influence the treatment outcomes of music and movement intervention from a neurological aspect.

The relationship between entrainment dynamics and reading fluency assessed by sensorimotor perturbation.

A consistent relationship has been found between rhythmic processing and reading skills. Impairment of the ability to entrain movements to an auditory rhythm in clinical populations with language-related deficits, such as children with developmental dyslexia, has been found in both behavioral and neural studies. In this study, we explored the relationship between rhythmic entrainment, behavioral synchronization, reading fluency, and reading comprehension in neurotypical English- and Mandarin-speaking adults. First, we examined entrainment stability by asking participants to coordinate taps with an auditory metronome in which unpredictable perturbations were introduced to disrupt entrainment. Next, we assessed behavioral synchronization by asking participants to coordinate taps with the syllables they produced while reading sentences as naturally as possible (tap to syllable task). Finally, we measured reading fluency and reading comprehension for native English and native Mandarin speakers. Stability of entrainment correlated strongly with tap to syllable task performance and with reading fluency, and both findings generalized across English and Mandarin speakers.

Resonance as a Design Strategy for AI and Social Robots.

Resonance, a powerful and pervasive phenomenon, appears to play a major role in human interactions. This article investigates the relationship between the physical mechanism of resonance and the human experience of resonance, and considers possibilities for enhancing the experience of resonance within human–robot interactions. We first introduce resonance as a widespread cultural and scientific metaphor. Then, we review the nature of “sympathetic resonance” as a physical mechanism. Following this introduction, the remainder of the article is organized in two parts. In part one, we review the role of resonance (including synchronization and rhythmic entrainment) in human cognition and social interactions. Then, in part two, we review resonance-related phenomena in robotics and artificial intelligence (AI). These two reviews serve as ground for the introduction of a design strategy and combinatorial design space for shaping resonant interactions with robots and AI. We conclude by posing hypotheses and research questions for future empirical studies and discuss a range of ethical and aesthetic issues associated with resonance in human–robot interactions.

Rhythmic firing of neurons in the medulla of conscious freely behaving rats: rhythmic coupling with baroreceptor input.

Recent investigations emphasized the importance of neural control of cardiovascular adjustments in complex behaviors, including stress, exercise, arousal, sleep-wake states, and different tasks. Baroreceptor feedback is an essential component of this system acting on different time scales from maintaining stable levels of cardiovascular parameters on the long-term to rapid alterations according to behavior. The baroreceptor input is essentially rhythmic, reflecting periodic fluctuations in arterial blood pressure. Cardiac rhythm is a prominent feature of the autonomic control system, present on different levels, including neuron activity in central circuits. The mechanism of rhythmic entrainment of neuron firing by the baroreceptor input was studied in great detail under anesthesia, but recordings of sympathetic-related neuron firing in freely moving animals remain extremely scarce. In this study, we recorded multiple single neuron activity in the reticular formation of the medulla in freely moving rats during natural behavior. Neurons firing in synchrony with the cardiac rhythm were detected in each experiment (n = 4). In agreement with prior observations in anesthetized cats, we found that neurons in this area exhibited high neuron-to-neuron variability and temporal flexibility in their coupling to cardiac rhythm in freely moving rats, as well. This included firing in bursts at multiples of cardiac cycles, but not directly coupled to the heartbeat, supporting the concept of baroreceptor input entraining intrinsic neural oscillations rather than imposing a rhythm of solely external origin on these networks. It may also point to a mechanism of maintaining the basic characteristics of sympathetic neuron activity, i.e., burst discharge and cardiac-related rhythmicity, on the background of behavior-related adjustments in their firing rate.

How to Investigate the Effect of Music on Breathing during Exercise: Methodology and Tools.

Music is an invaluable tool to improve affective valence during exercise, with the potential contribution of a mechanism called rhythmic entrainment. However, several methodological limitations impair our current understanding of the effect of music on relevant psychophysiological responses to exercise, including breathing variables. This study presents conceptual, methodological, and operational insight favoring the investigation of the effect of music on breathing during exercise. Three tools were developed for the quantification of the presence, degree, and magnitude of music-locomotor, locomotor-breathing, and music-breathing entrainment. The occurrence of entrainment was assessed during 30 min of moderate cycling exercise performed either when listening to music or not, and was complemented by the recording of relevant psychophysiological and mechanical variables. Respiratory frequency and expiratory time were among the physiological variables that were affected to a greater extent by music during exercise, and a significant (p < 0.05) music-breathing entrainment was found in all 12 participants. These findings suggest the importance of evaluating the effect of music on breathing responses to exercise, with potential implications for exercise prescription and adherence, and for the development of wearable devices simultaneously measuring music, locomotor, and breathing signals.

Memory-Paced Tapping to Auditory Rhythms: Effects of Rate, Speech, and Motor Engagement.

Humans have a near-automatic tendency to entrain their motor actions to rhythms in the environment. Entrainment has been hypothesized to play an important role in processing naturalistic stimuli, such as speech and music, which have intrinsically rhythmic properties. Here, we studied two facets of entraining one's rhythmic motor actions to an external stimulus: (a) synchronized finger tapping to auditory rhythmic stimuli and (b) memory-paced reproduction of a previously heard rhythm. Using modifications of the Synchronization-Continuation tapping paradigm, we studied how these two rhythmic behaviors were affected by different stimulus and task features. We tested synchronization and memory-paced tapping for a broad range of rates, from stimulus onset asynchrony of subsecond to suprasecond, both for strictly isochronous tone sequences and for rhythmic speech stimuli (counting from 1 to 10), which are more ecological yet less isochronous. We also asked what role motor engagement plays in forming a stable internal representation for rhythms and guiding memory-paced tapping. Our results show that individuals can flexibly synchronize their motor actions to a very broad range of rhythms. However, this flexibility does not extend to memory-paced tapping, which is accurate only in a narrower range of rates, around ~1.5 Hz. This pattern suggests that intrinsic rhythmic defaults in the auditory and/or motor system influence the internal representation of rhythms, in the absence of an external pacemaker. Interestingly, memory-paced tapping for speech rhythms and simple tone sequences shared similar "optimal rates," although with reduced accuracy, suggesting that internal constraints on rhythmic entrainment generalize to more ecological stimuli. Last, we found that actively synchronizing to tones versus passively listening to them led to more accurate memory-paced tapping performance, which emphasizes the importance of action-perception interactions in forming stable entrainment to external rhythms.

Human unintentional and intentional interpersonal coordination in interaction with a humanoid robot.

In order to establish natural social synchrony between two humans, two requirements need to be fulfilled. First, the coupling must be bi-directional. The two humans react to each other’s actions. Second, natural social bodily synchronization has to be intentional or unintentional. Assuming that these essential aspects of human-human interactions are present, the present paper investigates whether similar bodily synchrony emerges between an interacting human and an artificial agent such as a robot. More precisely, we investigate whether the same human unintentional rhythmic entrainment and synchronization is present in Human Robot Interaction (HRI). We also evaluate which model (e.g., an adaptive vs non adaptive robot) better reproduces such unintentional entrainment. And finally, we compare interagent coordination stability of the HRI under 1) unidirectional (robot with fixed frequency) versus bidirectional (robot with adaptive frequency) rhythmic entrainment and 2) human intentional versus unintentional coupling. Fifteen young adults made vertical arm movements in front of the NAO robot under five different conditions of intentional/unintentional and unidirectional/bidirectional interactions. Consistent with prior research investigating human-human interpersonal coordination, when humans interact with our robot, (i) unintentional entrainment was present, (ii) bi-directional coupling produced more stable in-phase un-intentional and intentional coordination, (iii) and intentional coordination was more stable than unintentional coordination. To conclude, this study provides a foundation for modeling future social robots involving unintentional and bidirectional synchronization—aspects which seem to enhance humans’ willingness to interact with robots.

Alpha fluctuations regulate the accrual of visual information to awareness

Endogenous brain processes play a paramount role in shaping up perceptual phenomenology. This is illustrated by the alternations experienced by humans (and other animals) when watching perceptually ambiguous, static images. We hypothesised that endogenous alpha fluctuations in the visual cortex pace the accumulation of sensory information leading to perceptual outcomes. Here, we addressed this hypothesis using binocular rivalry combined with visual entrainment and electroencephalography in humans (64 female, 53 male). The results revealed a correlation between the individual frequency of alpha oscillations in the occipital cortex and perceptual alternation rates experienced during binocular rivalry. In subsequent experiments we show that regulating endogenous brain activity via rhythmic entrainment produced corresponding changes in perceptual alternation rate. These changes were observed only in the alpha range but not at lower entrainment frequencies, and were much reduced when using arrhythmic stimulation. Additionally, entraining at frequencies above the alpha range did not result in speeding up perceptual alternation rates. Overall, these findings support the notion that visual information is accumulated via alpha cycles to promote the emergence of conscious perceptual representations. We suggest that models of binocular rivalry incorporating posterior alpha as a pacemaker can provide an important advance in the comprehension of the dynamics of visual awareness.

Alluring Monotony + Luminous Grids

The rhythmic repetitions that run through weaving, dance, music, poetry, and prayer are guidelines that can be followed with eyes closed and hands outstretched toward a sensory experience of the sacred. This essay traces the synergies between these somatic practices and the potential of rhythmic entrainment to generate numinous states. As cultural paradigms shift from the disembodied mind to mindful embodiment, weaving and cloth provide models for relational thinking and nonhierarchical structures. The author forwards the notion that the act of weaving sensitizes the body-mind to a perception of the interconnected universe.

In Time with the Beat: Entrainment in Patients with Phonological Impairment, Apraxia of Speech, and Parkinson's Disease.

In the present study, we investigated if individuals with neurogenic speech sound impairments of three types, Parkinson’s dysarthria, apraxia of speech, and aphasic phonological impairment, accommodate their speech to the natural speech rhythm of an auditory model, and if so, whether the effect is more significant after hearing metrically regular sentences as compared to those with an irregular pattern. This question builds on theories of rhythmic entrainment, assuming that sensorimotor predictions of upcoming events allow humans to synchronize their actions with an external rhythm. To investigate entrainment effects, we conducted a sentence completion task relating participants’ response latencies to the spoken rhythm of the prime heard immediately before. A further research question was if the perceived rhythm interacts with the rhythm of the participants’ own productions, i.e., the trochaic or iambic stress pattern of disyllabic target words. For a control group of healthy speakers, our study revealed evidence for entrainment when trochaic target words were preceded by regularly stressed prime sentences. Persons with Parkinson’s dysarthria showed a pattern similar to that of the healthy individuals. For the patient groups with apraxia of speech and with phonological impairment, considerably longer response latencies with differing patterns were observed. Trochaic target words were initiated with significantly shorter latencies, whereas the metrical regularity of prime sentences had no consistent impact on response latencies and did not interact with the stress pattern of the target words to be produced. The absence of an entrainment in these patients may be explained by the more severe difficulties in initiating speech at all. We discuss the results in terms of clinical implications for diagnostics and therapy in neurogenic speech disorders.

Oscillatory entrainment mechanisms and anticipatory predictive processes in children with autism spectrum disorder.

Anticipating near-future events is fundamental to adaptive behavior, whereby neural processing of predictable stimuli is significantly facilitated relative to nonpredictable events. Neural oscillations appear to be a key anticipatory mechanism by which processing of upcoming stimuli is modified, and they often entrain to rhythmic environmental sequences. Clinical and anecdotal observations have led to the hypothesis that people with autism spectrum disorder (ASD) may have deficits in generating predictions, and as such, a candidate neural mechanism may be failure to adequately entrain neural activity to repetitive environmental patterns, to facilitate temporal predictions. We tested this hypothesis by interrogating temporal predictions and rhythmic entrainment using behavioral and electrophysiological approaches. We recorded high-density electroencephalography in children with ASD and typically developing (TD) age- and IQ-matched controls, while they reacted to an auditory target as quickly as possible. This auditory event was either preceded by predictive rhythmic visual cues or was not preceded by any cue. Both ASD and control groups presented comparable behavioral facilitation in response to the Cue versus No-Cue condition, challenging the hypothesis that children with ASD have deficits in generating temporal predictions. Analyses of the electrophysiological data, in contrast, revealed significantly reduced neural entrainment to the visual cues and altered anticipatory processes in the ASD group. This was the case despite intact stimulus-evoked visual responses. These results support intact behavioral temporal prediction in response to a cue in ASD, in the face of altered neural entrainment and anticipatory processes.NEW & NOTEWORTHY We examined behavioral and EEG indices of predictive processing in children with ASD to rhythmically predictable stimuli. Although behavioral measures of predictive processing and evoked neural responses were intact in the ASD group, neurophysiological measures of preparatory activity and entrainment were impaired. When sensory events are presented in a predictable temporal pattern, performance and neuronal responses in ASD may be governed more by the occurrence of the events themselves and less by their anticipated timing.

Drum Circles and the Effect on Wellbeing in a Community Setting

Background: Wellbeing plays an essential role in a complete and health community. Participatory arts interventions are popular to address wellbeing. Participatory drum circles can lead to social resilience, emotional completeness, and mental health benefits. The literature in the field of arts in health demonstrate the specific ways a drum circle may affect wellbeing through socialization, rhythmic entrainment, and expression. Although there are many great resources, many lack the specific tools to facilitate a drum circles as it pertains to specific technique and styles often utilized in percussion in the field of arts in health.&#x0D; Methods: The project used a mixed methods research design. A convergent mixed methods design will be used to collect quantitative data from the Warwick Edinburgh Mental Wellbeing Scale and the qualitative data will be received from a focus group. The results will be compared with the hopes of yielding similar themes.&#x0D; Results: The results of the Warwick Edinburgh Mental Wellbeing scale demonstrate an increase of the average wellbeing score after the four-week intervention by 2.88 points. The focus group’s final themes were 1) the core of the drum circle is driven from the facilitator fostering a strong sense of community that supports being inclusionary, respectful, and social; 2) Learning new skills in a community group benefits participants confidence because a) the curriculum progresses naturally and easily and b) rhythm is an innate and natural part of everyday life for individuals, making drum circles more comfortable.

Balance Based Torso Weighting and Rhythmic Entrainment in a Patient Post Concussion/TBI

<h3>Research Objectives</h3> Use of entrainment and by upweighting proprioception via Balance-Based Torso-Weighting (BBTW) to allow for improvement in sensorimotor function. <h3>Design</h3> Single Case presentation. <h3>Setting</h3> CARF certified inpatient Transitional Living Center (TLC). <h3>Participants</h3> 49-yo female with a right frontal TBI four years prior. Primary deficits included discoordination, impaired balance, vestibular dysfunction, inability to perform dual tasks, and truncal/extremity ataxia. Goals included developing strategies for sensory overload, decreased falls, and improved communication. <h3>Interventions</h3> The use of an interactive metronome (IM) and the BBTW protocol utilizing a weighted torso vest. <h3>Main Outcome Measures</h3> Sensory Organization Testing (SOT), COG alignment, and IM. <h3>Results</h3> LO demonstrated improvement using IM in both focus/attention through her Task Average (TA) and motor skill/precision and rhythm through her Variable Average (VA). On evaluation, she demonstrated severe deficits with her TA indicating poor attention/focus. This worsened with guide sounds indicative of sensory overload. With the use of the BBTW vest, she demonstrated significant improvement with her TA and VA. By Discharge, she demonstrated further improvement with and without the use of the BBTW vest and with and without guide sounds. On Sensory Organization Testing (SOT), she demonstrated significant improvement in her sensory analysis with the use of the BBTW at evaluation and at discharge. There was significant change without the use of the BBTW, however, a review of her COG alignment showed decreased variability at discharge without the use of the BBTW. <h3>Conclusions</h3> Use of the BBTW vest and utilization of entrainment via IM were two of the most beneficial treatment strategies with collected pilot data that demonstrated improvement in sustained/divided attention, postural responses, timing, motor control, and improved increased tolerance of visual and auditory stimulation with and without the use of the Balance Based Torso Weighting (BBTW). In conclusion, the combination of BBTW and IM was a useful treatment intervention for this patient with TBI. These modalities are low cost and risk and demonstrate great potential for the treatment of patients with residual impairment beyond the expected recovery period after sustaining a TBI. <h3>Author(s) Disclosures</h3> N/A

Group dancing as the evolutionary origin of rhythmic entrainment in humans

An ecologically-valid approach to the evolutionary origins of rhythmic entrainment in humans has to address not one but two key issues: first, the capacity to generate acoustic rhythms, and second, the ability to entrain body movements to them. Most research in this area has ignored the first issue altogether and has instead placed all of the emphasis on motor entrainment skills per se. But this begs the question of how auditory rhythms came to be generated in the first place. I discuss evolutionary models that explicitly link the mechanisms of body entrainment to the mechanisms of sound generation. The most plausible models are those in which these processes occur interactively and mutually through group dancing, employing not only visual and haptic cues for entrainment but percussive sounds generated through body movements, most especially locomotor movements. Body percussion during movement creates a link between motor and sensory components of interpersonal entrainment.

Expectancy-based rhythmic entrainment as continuous Bayesian inference.

When presented with complex rhythmic auditory stimuli, humans are able to track underlying temporal structure (e.g., a "beat"), both covertly and with their movements. This capacity goes far beyond that of a simple entrained oscillator, drawing on contextual and enculturated timing expectations and adjusting rapidly to perturbations in event timing, phase, and tempo. Previous modeling work has described how entrainment to rhythms may be shaped by event timing expectations, but sheds little light on any underlying computational principles that could unify the phenomenon of expectation-based entrainment with other brain processes. Inspired by the predictive processing framework, we propose that the problem of rhythm tracking is naturally characterized as a problem of continuously estimating an underlying phase and tempo based on precise event times and their correspondence to timing expectations. We present two inference problems formalizing this insight: PIPPET (Phase Inference from Point Process Event Timing) and PATIPPET (Phase and Tempo Inference). Variational solutions to these inference problems resemble previous "Dynamic Attending" models of perceptual entrainment, but introduce new terms representing the dynamics of uncertainty and the influence of expectations in the absence of sensory events. These terms allow us to model multiple characteristics of covert and motor human rhythm tracking not addressed by other models, including sensitivity of error corrections to inter-event interval and perceived tempo changes induced by event omissions. We show that positing these novel influences in human entrainment yields a range of testable behavioral predictions. Guided by recent neurophysiological observations, we attempt to align the phase inference framework with a specific brain implementation. We also explore the potential of this normative framework to guide the interpretation of experimental data and serve as building blocks for even richer predictive processing and active inference models of timing.

Machine learning accurately classifies neural responses to rhythmic speech vs. non-speech from 8-week-old infant EEG

Currently there are no reliable means of identifying infants at-risk for later language disorders. Infant neural responses to rhythmic stimuli may offer a solution, as neural tracking of rhythm is atypical in children with developmental language disorders. However, infant brain recordings are noisy. As a first step to developing accurate neural biomarkers, we investigate whether infant brain responses to rhythmic stimuli can be classified reliably using EEG from 95 eight-week-old infants listening to natural stimuli (repeated syllables or drumbeats). Both Convolutional Neural Network (CNN) and Support Vector Machine (SVM) approaches were employed. Applied to one infant at a time, the CNN discriminated syllables from drumbeats with a mean AUC of 0.87, against two levels of noise. The SVM classified with AUC 0.95 and 0.86 respectively, showing reduced performance as noise increased. Our proof-of-concept modelling opens the way to the development of clinical biomarkers for language disorders related to rhythmic entrainment.

Measuring emotional music experience: Spreading activation and BRECVEMA mechanisms

Spreading activation in the cognitive network explains why music is experienced as familiar or likable. It might also be a premise for the emotion-inducing mechanisms of the BRECVEMA framework (Brain stem reflexes, Rhythmic entrainment, Evaluative conditioning, Contagion, Visual imagery, Episodic memory, Musical expectancy, Aesthetic judgment). Both perspectives constitute important aspects of music experience and are influenced by individual differences. In two studies ( n = 125 and n = 153), potential indicators for spreading activation and BRECVEMA mechanisms for single instances of music listening were assessed with a new questionnaire. The results indicated that Typicality of music, Liking, and attentional Engagement underlie spreading activation. The mechanisms Evaluative conditioning and Contagion in unison (Conditioning/Contagion), as well as Visual imagery and Episodic memory could be reliably assessed. Findings revealed that (a) Engagement, Conditioning/Contagion, and Visual imagery increased with musical expertise; (b) spreading activation and mechanisms were stronger when listening to self- rather than pre-selected music; (c) sad music evoked stronger Engagement, Conditioning/Contagion, and Episodic memory when it was self-selected; (d) spreading activation and mechanisms were associated with music empathizing and systemizing and the emotion regulation strategy reappraisal; and finally, (e) regulating sadness with sad music was associated with habitual suppression and stronger Conditioning/Contagion.