Discussion
Examining the largest sample of misophonia participants to date, the aim
of this study was to investigate the relationship between misophonia and
mimicry. More specifically, three questions were addressed: (i)
relationship between the likelihood to mimic as a function of misophonia
severity, (ii) whether the act of mimicking was related to a particular
set of trigger sound categories (as defined by the MQ (Wu et al.,
2014)), and (iii) what benefits, if any, mimicking provided to people
with misophonia (identified through the IMQ).
Our results show that mimicry is widely prevalent in misophonia and that
its likelihood increases with greater misophonia severity. This finding
is consistent with results from a recent neuroimaging study from our
group (Kumar et al, 2021), which for the first time hypothesized the
role of ‘mirroring’ the action, and not the sounds per se, as the
primary driving factor in misophonia. The neuroimaging study, by showing
stronger resting state connectivity between auditory and visual cortex
and the pre-motor area of the brain in misophonia, argued that watching
or hearing action sounds (e.g., orofacial movement for eating/ chewing
sounds) of the trigger-person results in driving the same part of the
motor cortex that is involved in generating the perceived action. The
current study, based on self-reported measures of how people with
misophonia respond to and cope with triggers in daily life, provides
support to the ‘hyper-mirroring’ hypothesis of misophonia.
The phenomenon of mimicry is ubiquitous in social interactions and has
been a well-researched topic in social psychology and neuroscience
(Prochazkova and Kret, 2017; Arnold and Winkielman, 2020; Palagi et al.,
2020). Mimicry can be broadly divided into two categories: intentional
and spontaneous. Intentional mimicry (sometimes also called imitation or
emulation) involves explicit intention to copy and reproduce somebody
else’s actions. In a misophonia context, this would be the case when a
person with misophonia, on seeing/hearing the actions (e.g., orofacial
movement for eating/chewing sounds) of the trigger-person, deliberately
repeats the observed action. Spontaneous mimicry, on the other hand, is
the automatic reproduction of another individual’s motor movements,
behaviour, or facial expression without explicit intention or awareness
to do so. For example, in a seminal study (Chartrand and Bargh, 1999)
demonstrating spontaneous mimicry, a confederate manipulated her actions
while interacting with participants: in different sessions, she either
touched her face or shook her leg while both the confederate and
participants were involved in an irrelevant task of describing pictures
to each other. Analysis of video recording of the interaction showed
that participants touched their face more in the presence of a
face-touching confederate and wiggled their foot more in the presence of
a foot-shaking confederate. Debriefing after the experiment showed that
participants did not notice any ‘odd’ behaviour of the confederate and
were not aware of their mimicking of the actions of the confederate
implying that reproduction of the actions was implicit and
unintentional. With respect to misophonia, spontaneous mimicry would
occur if mere observation or listening to the trigger sounds of action
automatically elicits a corresponding action (e.g., orofacial movements
for eating/chewing sounds) in a person with misophonia with them not
knowing anything about it. Although not within the misophonia context,
spontaneous mimicry has been shown in the domain of eating behaviour:
people are more likely to take a bite of food or sip of a drink when
their companion does so (Larsen et al., 2010; Hermans et al., 2012; Bell
et al., 2019). Even the sounds of eating alone can elicit eating mimicry
in the listener (Zin et al., 2015).
How does misophonia relate to mimicry? The basic premise of our argument
is that misophonia is a result of increased spontaneous mimicry in
response to the actions (e.g., orofacial movement) of the trigger-person
that produce trigger sounds (e.g., eating/chewing sounds). The excessive
spontaneous mimicry, which possibly arises due to the failure of
contextual modulation (either amplified in excess or not suppressed
enough by the contextual/situational settings) is then perceived as
inappropriate in terms of interfering in a person’s current goals and
actions. This strong drive, initiated by an external source, to repeat
the actions can be felt as violating or invading personal space or can
lead to a sense of loss of self-control. This is consistent with people
with misophonia describing their experience of trigger sounds as
‘invasive’, ‘intrusive’, ‘insulting’, ‘violating’ and ‘offensive’ (Rouw
and Erfanian, 2018). There is also evidence that trigger sounds are
perceived as interfering in one’s current goals. In a study using a
Stroop task, Daniels et al (2020) showed that people with misophonia are
impaired in maintaining the current goals of the task specifically in
the presence of trigger sounds. Since perceived interference,
particularly when it is attributed to another social agent, can be a
cause of anger (Izard, 1991), this also explains why anger, and in
extreme cases, aggression could be a dominating emotional response in
misophonia. One possible way to counter the covert drive for spontaneous
mimicry is to overtly mimic the action of the trigger-person (e.g.,
orofacial movements in response to sounds of eating/chewing). The overt
mimicry, in contrast to implicit and unintentional spontaneous mimicry,
is intentional and done voluntarily as a coping mechanism to ‘cancel
out’ the trigger sound. The reason why overt mimicry in misophonia can
‘dampen’ the response to the external trigger is that self-executed
movement alone (with or without any sound generation, e.g. orofacial
movement) done in synchrony with external movements can lead to
predictions about the upcoming stimulus, much like an efference copy or
corollary discharge making a prediction of the sensory consequences of
self-generated actions (Blakemore et al., 2000), which is then compared
with the actual stimulus and the discrepancy between the two (prediction
error) is processed further. The amount of dampening of the trigger
stimulus would depend on how accurately the self-action can predict the
stimulus: the higher the accuracy of prediction, the lower the
prediction error and thus the greater the relief provided by the overt
mimicry. Moreover, the overt mimicry can provide an increased sense of
self-control: rather than being a ‘passive’ recipient of the excessive
drive to spontaneously mimic the actions of the trigger-person, the
person with misophonia can now do the same action which is under their
control. This is in agreement with subjective reports of several people
with misophonia who describe their act of deliberate mimicking as a
means of ‘gaining control over the situation’ (as told to the senior
author in personal communication/discussion).
Our data show that the probability of mimicking increases with
misophonia severity (Figure 1). When asked about the type of mimicry,
50.5 % (sum of ‘sometimes’, ‘often’ and ‘always’, Figure 4(i))
described their mimicry to be spontaneous and out of their control.
About 80% (Figure 4(ii)) of people who reported mimicking, described
their act as deliberate and voluntarily driven. As predicted by our
model, intentional mimicry provides relief (reported by 68%, Figure
4(iii)) and makes the person feel under control (60.4 %, Figure 4(iv)).
Analysis using multivariable logistic regression showed that, out of all
the different types of sound categories examined, sensitivity to eating
sounds was the strongest predictor of mimicry (Table 1 and Figure 2).
Multivariate analysis using PCA showed that eating/nasal/throat sounds
and mimicry loaded onto the same component with high positive loadings
implying a positive association between the component and these
variables. The eating/nasal/throat sounds are orofacial (face/mouth)
sounds involving movement of orofacial muscles and these sounds happen
to be the dominant trigger sounds in misophonia (Schröder et al., 2013;
Kumar et al., 2014; Jager et al., 2020). We understand there are trigger
sounds which are of non-orofacial origins (Hansen et al., 2021) such as
pen clicking, keyboard typing, and other environmental sounds. Although
the questionnaire did not have mention of these specific sounds, it did
include ‘environmental sounds’ as one of the categories and no mimicking
effect was observed using either logistic regression or PCA. However,
this category is very broad and whether mimicking is restricted to a
specific example of this category needs further investigation. The
questionnaire also contained a ‘repetitive tapping sound’ which is the
closest possible to clicking pen/keyboard typing but no mimicking effect
was observed. Although we did not find evidence of mimicking for
non-orofacial sounds, the question remains open. One explanation is
likely due to the under-representation of triggers of non-orofacial
origin in the current sample size given the high prevalence of orofacial
sounds as triggers. This would require a further study which balances
representation of different trigger types in the sample. Interestingly,
logistic regression analysis also showed consonant/vowel sounds
significantly correlated with mimicry. Whether these sounds trigger
reaction because of the speech/linguistic content or because these
sounds are mouth sounds is not clear and their relation to mimicry needs
further investigation.
What is the brain mechanism of excessive spontaneous mirroring in
misophonia? There is evidence that a ‘mirror neuron system’ (MNS) which
contains ‘mirror-neurons’ may underly mimicry in humans (Buccino et al.,
2001; Rizzolatti and Craighero, 2004). Mirror neurons fire not only when
the subject executes an action but also when the subject sees or hears
the action performed by another individual, thereby creating a
‘perception-action’ link. In our recent study (Kumar et al., 2021),
based on the findings of stronger coupling between auditory (and visual)
cortex and orofacial motor cortex in people with misophonia, we argued
for ‘hyper-mirroring’ as the basis of misophonia. This means that the
perception of seeing or hearing another individual producing
eating/chewing sounds is ‘mirrored’ in the orofacial motor cortex to a
greater degree in people with misophonia compared to control
participants. This hyper-mirroring then reproduces the action which
manifests as (spontaneous) mimicry. Our brain model of ‘hyper-mirroring’
and prevalence of spontaneous mimicry in the current work are therefore
consistent with each other.