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The curious phenomenon of contagious yawning
Echokinetic yawning, theory of mind, and empathy
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Daquin G, J Micallef, O Blin Yawning
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Why do people yawn ? 
Neural basis of drug induced yawning Cooper SJ, Dourish CT 
Neurophysiology of yawning
Content and Contagion in Yawning Sarnecki
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la lettre du 1 sept. 2007
The curious phenomenon
of contagious yawning
O. Walusinski & B. Deputte
Echokinetic yawning, theory of mind,
and empathy 2007
Robert Whytt (1714-1766)
"There is still a more wonderful sympathy between the nervous system of different persons"
Observations on the nature, causes and cure of those disorders which have been commonly called nervous, hypochondriac or hysteric, (1767)  
Contagious yawning: the role of self-awareness and mental state attribution Platek SMet al
Yearning to yawn: the neural basis of contagious yawning Schurmann, Hari et al
Contagious yawning and the brain Platek S, Mohamed F, Gallup G
Yawning Surprising facts ans misleading myths about our health Anahad O'Connor
Yawning: unsuspected avenue for a better understanding of arousal and interoception
A famous saying states that a good yawner will induce yawning in seven people. Contagiousness is often mentioned. This term, though, is designed for infectious diseases when, through direct or indirect contact, a healthy individual becomes sick through the transmission of a virus or microbe. The replication of behaviour does not suppose the presence of a transmission agent. It would appear more appropriate, therefore, to refer to mimetism, a term proposed by W. Baldwin in 1894, or to synchronous actions, rather than imitation which could involve a voluntary participation, which is not the case here.
Ethological studies of non-human primates show that at certain times an entire group goes about yawning, without the possibility for one member to be aware of another yawner, either by sight, hearing or smell. One could not consider this type of behaviour as comparable to replication among humans, but could link it, for instance, with a synchronous trigger of activities related to circadian rest-activity rhythms. Obviously, in the case of human, these two variants can be seen sometimes as one and the same. Given the above and other ethological observations, one can find that yawning replication is found only in human.
This replication is triggered involuntarily. Neither does the yawner want to make others yawn, neither is the spectator-receiver of the replication aware of a need to yawn. The latter's yawn is also triggered involuntarily, but only and only if the level of vigilance allows for it. Indeed, the involvement in a sustained intellectual task (that is with high concentration or with an optimum level of vigilance) will not allow the triggering of a yawn. This point is fundamental to the human ethological explanation of the role of synchronisation of vigilance states between two individuals subjected to the transmission of yawning.
How is this replication triggered? Sight is a powerful stimulant. R. Provine shows that 55% of spectators viewing a video showing 30 successive yawns will yawn within five minutes. The latency period varies from a few seconds to five minutes. The latency period and the duration of the viewing have not allowed for the precise identification of a rule, a type of specific synchronisation. R. Provine has also verified that there is no need whatsoever for the face of the yawner to be in a precise visual plane relative to the subject of the contagion. Face to face, at 90°, 180°, 270° relative to one another, contagion there is. The existence of a susceptibility to contagion among blind subjects confirms that sight is not the only trigger. Viewing part of the face only, such as a wide open mouth, does not trigger replication. Therefore a multimodal perception of the whole facial configuration and of audible respiratory moments is needed, along with coordinated dynamics for replication to happen.
The replication of yawning seems to originate at a basic level because it is independent of knowing the triggerer beforehand, independent of racial, education or socio-cultural characteristics, which indicates an absence of mnestic intervention. There is no need of explicit characterisation for the other party to be subjected to replication. There is need for a vigilance level situated between somnolence and sustained concentration and for the unconscious perception of the other party, while in a position to notice the rigorous chronology of the unfolding yawn via its visual and/or audio components of mouth opening, specific modifications of other facial traits, ventilation activity and sounds reflecting deep and prolonged inspiration (the acme), and expiration, but to a lesser degree.
Following such perception, the motor trigger of the yawning reflex is also involuntary and stems from the setting into action of sub-cortical motor loops (gray nucleus - brainstem). In parallel, there is a conscious perception of the development of this phenomenon, of its stimulus and of its contextual valence through the interoception pathways, which lead to a conscious hedonist perception.
Ethology allows for the distinction between two types of reactions regarding an external stimulus:
1°) reactions qualifiable as common programmes for the animal kingdom as a whole, notably all mammals. These reactions seem necessary for individual or group survival. They are contagious through non-verbal communication. This is a cognitive process of direct, immediate and non-conscious communication triggering innate or acquired motor patterns such as escape or avoidance. The replicated yawning in human can only be partly related to this archaic behavioural level. Its automatism is close to the latter. But its random component and its possible latency are quite different.
2°) reactions with cognitive participation of an emotional nature. An emotion expressed by a fellow being calls for decoding through an analytical treatment of the information. As a basis of social cognition, facial expressions reflecting emotions underly complex and flexible cognitive processes. Only human primates demonstrate the capacity to perceive others as agents endowed with intention, along with the ability to identify. This capacity to think about others and their desires is probably at the root of the complexity and sophistication of Homo sapiens' social bevaviour. (Theory of the mind). This is the basis of conscious empathy: to understand the feeling of the other, to feel personally what the other feels. The replication of yawning is akin to decoding an emotion, the other's state of vigilance, but at an unconscious, automatic level allowing for the synchronisation of the state of vigilance between individuals, which one could qualify as an instinctive, involuntary empathy. This capacity to in tune with unconscious affects rests on implicit communications, developed over the course of evolution, but whose neurobiological mechanisms are just starting to be understood.
Research by J. Decety has helped identify participating cortical structures when a subject imitates the actions performed by an experimenter or when the subject's actions are imitated by an experimenter, in comparison to a situation where actions are produced without imitation: "As expected, over and above the regions involved in motor control, a network of activation common to the parietal cortex and the frontal lobe (dorso-median prefrontal regions) was detected between these two imitation situations. This network of shared activations is consistent with the hypothesis of a common coding between the actions of one's self and those of another individual. When taken together, the neurophysiological data pertaining to the neuronal implementation of the three types of activity (preparation, simulation and observation in view of imitating) involving motor representations show that there is a close functional equivalence between them. »
The activation of the inferior frontal gyrus in the left hemisphere (which would correspond to the F5 region in the monkey) during the observation of actions can be explained by a silent verbalisation among the subjects. Indeed, this area belongs to Broca's region, the lesion of which provokes an aphasia. G.Rizzolati discovered in the macaque's ventral premotor cortex, in areas F4 and F5, groups of neurons called mirror neurons whose activity is correlated with the observation of another individual's action in function of its purpose, which shows the actions as being volitional. These neurons seem to exist in human. The bold speculation that supposes their involvement in this in-tune, mimetic yawning behaviour, is supported by the first functional imagery study, done by R. Hari (NeuroImage June 2003; 19, 2, Sup 1, S1-S101), showing the activation of the sulcus temporalis superior (STS) at the sight of a yawner. In opposition to other banal facial movements, the STS is specifically stimulated by the viewing of a yawn. The STS was identified long ago as the structure involved in the perception of movement involving facial characteristics and the expression of the mouth. The activation difference between non-specific facial movements and a yawn points to the specific activation of the STS during a yawn. It so happens that the STS is an essential component of the mirror-neuron system identified by V. Gallese et G. Rizzolatti, that is the neurophysiological foundation of the ability to imitate. Another interpretation is that the STS is part of the analysis system of visual behavioural information and, in the typical case of yawning, recognises the kinesodic pattern of this behaviour and its contextual valence, enriched by the previous emotional knowledge.
The perception of actions by another party would involve a simulation process that would lead to an understanding of intentions. This tuning-in on the part of the observer does not necessarily produce a movement or action. An inhibiting mechanism, activated in parallel and that can be located in the frontal area, would block the triggering of motor mimetic actions. Indeed, the study of human neurological pathology of frontal dysfunctions finds two circumstances where uninhibited imitation disturbs behaviours:
1°) The Gilles de la Tourette disease, affecting the prefrontal cortex, the basal limph nodes and the limbic system, combines four major elements: tics, the rare coprolalia behaviour, and the echolalia/echopraxia, echokinesis.
2°) The prefrontal or premotor syndrome is associated with a kinetic aphasia (lesions to the left hemisphere) and selectivity troubles of motor patterns, leaving intact the superior functions: de-automation of activities accompanied by perseverance and rudimentary and erroneous imitation, echokenesis and cetopraxia.
Could the replication of yawning be an uninhibited behaviour, physiologically speaking, that through its mechanisms would be somewhat akin to these pathologies?
In human, at what age does the replication of yawning start? As early as 1951, Piaget had shown that the sensitivity to the replication of yawning in babies only appeared during its second year, whereas newborns yawn frequently, maintaining a precocious behaviour developed during fetal life. A. Meltzoff proposes an ontogenic interpretation of this discord. During its first six months of life, the baby is able to imitate hand movements because it perceives surrounding hands as its own. However, it does not have a conscious notion of itself as an individual nor any perception of its own facial movements. Once the mirror test shows that the baby has self-perception as an autonomous individual and has acquired the capacity for self recognition in a mirror, the mental development of imitation is rounded out by the capacity to copy mimics, which explains why it is only in the second that the baby becomes sensitive to yawning contagion.
To sum up, on the assumption that the development of the frontal (motor) and prefrontal (premotor) cortex is specific to bipeds, it can proposed that yawning replication is a real example of echokinesis, a word coined by JM Charcot, which is characterised by three criteria:
- replication would be specifically human, to be interpreted as a behavioural mimetism,
- whereas upon observation of someone's motor behaviour what was seen is mimed through the motor areas of the observer and, more often than not, is not followed by motor actions consequent to frontal inhibition, yawning for its part is the result of uninhibited bevaviour, under certain conditions pertaining to vigilance,
- replication would have provided a selective advantage by allowing for an efficient synchronisation of vigilance levels between members of a group. It would be instrumental in a type of involuntary instinctive empathy, that would probably have appeared late in the evolution of hominids.
Abstract in English ..Why do people yawn ?
Yawning : an evolutionary perspective
The neural basis of contagious yawning
Contagious yawning: the role of self-awareness and mental state attribution
Empathy and contagion of yawning
DAVISON, William (Printer & Publisher of Alnwick)
Alnwick: printed and published by W. Davison, [1816]. Single sheet, image 133x220 on paper 187x265mm. Printed in black partly contemporary hand colour of a yellow wash, dustsoiled and a little frayed at the outer margins. (Isaac Some Alnwick caricatures; a note and handlist 18) In the period between 1812 and 1817, Davison produced a number of caricatures, amusing if somewhat crudely executed plates in the manner of Gilray, Rowlandson and Bunbury. In this instance, two men and a woman sit around a table yawning widely, with - in a nice example of product placement - a copy of Davison's list of his pharmacy products lies on the table.