Novel five-phase model for understanding the nature of misophonia, a conditioned aversive reflex disorder

Hypothesis and theory

The model presented in this section builds on the Dozier behavioral model (Figure 1). Figure 2 shows the additional components of the Mitchell-Dozier model, compared to the Dozier model. Whereas the Dozier model is a behavioral model, the Mitchell-Dozier model is a cognitive-behavioral model. The additional components include anticipatory anxiety and avoidance (phase one), thoughts, urges, and emotion-driven behavior (part of phase three), covert mental review (part of phase four), and environmental response and consequences (phase five).

Figure 2. Comparison of Mitchell-Dozier cognitive behavioral model and Dozier behavioral model of misophonia.

Additions to the Dozier behavioral model are shown in red.

The Mitchell-Dozier model consists of five phases, as shown in Figure 3. At the core of the five-phase Mitchell-Dozier model is a conditioned physical reflex that develops through stimulus-response Pavlovian conditioning (phase two). In this case a physical reflex refers to an automatic (and therefore without cognitive consideration) physical response to a stimulus, such as skeletal muscle contractions (including breathing muscles), internal muscles (esophagus, stomach, intestine), or physical sensations such as pain, numbness, heat on skin, flash of warmth, etc. For example, the sound of chewing (CS) could elicit the tensing of calf muscles or holding one’s breath (CR). Phase three includes intense, negative, emotional responses such as anger, disgust, and anxiety, as well as accompanying physiological distress, thoughts, urges, and emotion-driven behavior. Phases two and three occur while experiencing the trigger and phase three ends shortly after termination of the trigger stimulus. Phase four is the individual’s post-trigger coping responses to the emotional and physiological distress, including covert mental reviews of the trigger and overt behavior. The fifth and final phase is the environmental response and resulting internal and external consequences of the individual’s coping behaviors. Phases four and five include the period from the termination of the trigger stimulus until the effects of the trigger experience extinguish. The repeated, aversive experiences of phases two to five lead to feelings of anticipatory anxiety and avoidance in the individual’s daily life; thus, these feelings and behaviors form the pre-trigger phase one.

Figure 3. Mitchell-Dozier model of misophonia.

(1) Anticipatory anxiety and avoidance, (2) the misophonic trigger stimulus elicits the initial physical reflex (e.g., muscle flinch), (3) intense emotional response of misophonia, physiological distress, thoughts, urges and emotion driven behaviors while the trigger continues, (4) coping responses after the trigger, including covert mental review and overt behavior, and (5) environmental response and internal and external consequences. The dotted connection indicates phase 3 contributes to strengthening of the initial physical reflex, phases 2 to 5 contribute to strengthening anticipatory anxiety and avoidance of phase 1 and phase 5 contributes to strengthening phases 3 and 4.

Each phase attempts to explain the maintenance of the response and the individual’s subsequent impairment. Anticipatory anxiety and avoidance (phase one) contribute to increased arousal and greater awareness of triggers, resulting in an increased severity of the trigger experience. Phase two is a Pavlovian-conditioned physical reflex that strengthens with in vivo exposure to triggers. Phase three is a conditioned emotional response and associated physiological distress, thoughts, urges, and emotion-driven behavior, which also strengthens with in vivo exposure to triggers. Phase four includes both internal and external coping behaviors to the intense emotions and distress, in which patients regularly report a ‘mental review’ of the misophonic trigger as though it were an attack, which reinforces the belief that any subsequent trigger will be intolerable and must be avoided. Widely known are the aggressive or panic-like behavioral responses of individuals experiencing a misophonic trigger. Phase five includes internal and external consequences of misophonic individuals’ coping behaviors. Internal consequences include beliefs and new emotions based on environmental responses to anger and panic. These can include the development of emotions such as shame and guilt, beliefs regarding how ‘intolerable’ the trigger is, and intensified beliefs about the unfairness of having to experience the trigger. External consequences can serve as operant reinforcement for the explosive anger and/or panic behavior; for example, demands to stop the trigger and ‘death stares’ directed at the source of the trigger.

Taken together, phases two through five create overwhelming anticipatory anxiety and avoidant behavior (phase one) that perpetuate much of the dysfunction and impairment of misophonia. Phase one-related avoidant behaviors and emotions further intensify the learned responses associated with phases two through five, thus creating a dynamic, cyclical pattern of increasing dysfunction and despair. We present this as a linear model rather than the familiar circular model such as one for panic disorder (Clark, 1986). With panic disorder, the individual may experience a cycle of increasing distress triggered by a single thought. With misophonia, it is likely that at a molar level, cyclical interactions and effects occur, but at a molecular level, phase one is a setting event for the severity of the misophonic response, which is fundamentally linear, initiated by each instance of the misophonic trigger stimulus. The sections that follow explain the phases in greater detail. We begin with phase one, but we emphasize that phase two is the vital component of Pavlovian conditioning of a physical reflex critical to the development of misophonia. We recognize that there are likely many predisposing factors, including emotional awareness of moods of others, sensory sensitivity, and genetics, but these are beyond the scope of this article.

Phase one – Anticipatory anxiety and avoidance

We believe the origins of misophonia begin with Pavlovian conditioning (phase two) and subsequent responses (phases three through five). However, once the misophonic trigger exists, patients often talk about the fear and avoidance of the trigger, which is one of the primary areas of dysfunction, as the first step in the process. Anticipatory anxiety and avoidance of triggers is commonly reported and seems to be a universal characteristic among misophonia sufferers (Cusack et al., 2018; Dibb et al., 2021; Edelstein et al., 2013; Jager et al., 2020; Quek et al., 2018; Schadegg et al., 2021; Siepsiak et al., 2020; Wu et al., 2014). Avoidance of typical communal activities, such as eating together, enjoying social activities, and being in school or work environments, creates much of the dysfunction of misophonia. However, our model states that typical exposure to triggers increases the IPR (phase two) and intense emotions (phase three), therefore, simply eliminating avoidance in non-therapeutic environments is contraindicated. We find anxiety related to experiencing triggers can increase physiological distress and hypervigilant behavior, such as scanning for sources of triggers (e.g., individuals walking into a classroom and scanning to see if anyone is chewing gum). Our clinical cases attest that this increases the salience of triggers, strength of the IPR, and emotional responses. Since the person is looking for or anticipating triggers, they are thinking about them, re-experiencing them, and thus are more likely to find them. Anxious anticipation may cause tensing of the IPR muscle and result in the actual IPR muscle response being perceived and objectively measured as more intense than would be the case otherwise. For a person who immediately holds their breath as their IPR, if their chest muscles are already tightened because of anticipatory anxiety, the physical sensation of the IPR (holding breath) is likely intensified. Furthermore, regarding intensified emotional responses, individuals who are triggered when already experiencing anxiety typically perceive and exhibit intensified emotional responses, and anxiety severity is correlated with misophonia severity (Quek et al., 2018; Wu et al., 2014). Most individuals, whether they suffer from misophonia or not, can attest to experiencing emotions more intensely when already stressed (Du et al., 2018; Wang et al., 2020).

Anticipatory anxiety can present differently between children (Guzick et al., 2023; Guzick et al., under review) and adults (Schadegg et al., 2021; Wu et al., 2014). We view this in part due to increased emotional and behavioral self-control and autonomy with maturation. Clinically, we find that children often scan a particular family member for any indication of an increased likelihood of a trigger. For example, children may continuously scan a parent’s face to make sure their mouth is empty and chewing will not occur. This scanning behavior creates a dysfunctional environment, makes triggers more likely to be noticed and more severe, and can cause new triggers to develop to other physical actions. Per the previous example, the child becomes so intensely focused on possible chewing behavior that family functioning becomes difficult. The child may ask for reassurance, continually shift position to look at the face, and challenge the parent’s response that they don’t have anything in their mouth. The child may also have a strengthened or intensified response to the parent’s chewing behavior because of fight-or-flight responses prior to the trigger occurring. Further, as the child continuously observes the parent's facial expression, previously neutral events can become triggering stimuli; for example, a facial movement similar to chewing or something unrelated such as the parent adjusting their glasses.

Phase two – The initial physical reflex

A largely understudied aspect of misophonia is the existence of an IPR, although it has been reported in several case and quasi-experimental studies. In one case, the patient reported experiencing tensing of face and shoulder muscles and a sharp pain in her sternum (Dozier, 2015a). The pain in her chest was later ascribed to a reflex in which the IPR closed her windpipe and simultaneously caused her to inhale. Other case studies report an IPR of fist clenching (Dozier, 2015c) and jaw clenching (Dozier, 2022). Additionally, Dozier (2015b) reported IPR responses of seven individuals which included: shoulders; arms and chest; rightward head twist and right arm tense; arms, shoulders, and legs; goose bumps on upper arms; sensation behind the ears; and intestinal constriction. Therefore, phase two of the Mitchell-Dozier model is based on the limited data within some clinical case studies.

In a quasi-experimental study, 26 participants reported physical sensations in various locations when exposed to weak trigger stimuli (Dozier and Morrison, 2017). Weak triggers and infrequent exposure to triggers ensured participants did not experience strong emotions or physiological distress. The locations, while consistent with each participant, varied between participants, with the location of physical sensations ranging from head to toe. Most of the reported physical sensations can be attributed to muscle tightening (e.g., jaw muscle, shoulder sensation), but non-skeletal-muscle responses included numb skin, flash of warmth, sexual sensation, and nausea. A key limitation of this study was the reliance on self-report data and the absence of any temporal measurements (specifically the trigger-to-response delay). A subsequent pilot study with only three subjects addressed these limitations through electromyography and direct observation (Dozier et al., 2020). Direct observation revealed a movement of muscle or tissue that seemingly occurred with no perceptible delay to trigger onset. The electromyography data indicated a trigger-to-response delay of approximately 200ms for auditory triggers and 350ms for visual triggers. Collectively, these reports provide some evidence of the existence of an immediate misophonia-related IPR in some individuals with misophonia.

Furthermore, two studies measured physiological arousal using skin conductance response (SCR) in response to triggers (Edelstein et al., 2013; Kumar et al., 2017). In both studies, the SCR response was stable for the first two seconds of the trigger, and then rose monotonically for the remainder of the 15s trigger. However, SCR measures stress or physiological arousal at the skin level and cannot be used to measure immediate muscular flinches. In contrast to the delayed SCR response, the IPR begins within the first half-second following stimulus onset, so the delayed SCR response reported in these studies was not the IPR.

We propose that the IPR is different from the physical responses commonly reported in other studies. These studies reported physiological responses, including tense muscles, warmth, and increased heart rate, as physical responses to triggers. For example, studies report general muscle tensing, but an IPR would be specific muscles tensing, and be different from person to person. General warmth and increased heart rate are also physiological responses and not an IPR. Furthermore, numerous studies report that muscle tensing is often experienced by individuals when triggered in response to emotions (e.g., anger, anxiety), physiological distress, and fight-or-flight (Dibb et al., 2021; Edelstein et al., 2013; Jager et al., 2020; Jastreboff and Jastreboff, 2014; Potgieter et al., 2019; Rouw and Erfanian, 2018; Schröder et al., 2013; Schröder et al., 2019; Wu et al., 2014; Zhou et al., 2017). Similarly, muscle tension and other physical responses reported by individuals as part of the misophonia response have generally been understood as part of the emotions and distress of misophonia. Within the Mitchell-Dozier model, however, these responses would be categorized as part of phase three (physiological distress), rather than the IPR of phase two.

It can be difficult to distinguish the IPR from other physical responses, but there are several ways to differentiate them. First, the IPR will be a consistent initial response for a specific trigger. For example, if a person’s IPR for a sniff trigger is shoulder tensing, then shoulder tensing will always occur when the person is triggered by a sniff. Also, the IPR will not contain topographic variations based on the current situation, such as orienting toward the person making the trigger. An orienting response would be part of phase three as a component of fight-or-flight or other defensive motivational responding. For example, one individual’s IPR was clenching his right arm and turning his head to the right. This response occurred every time he was triggered, regardless whether the trigger source was to the right, left, in front, or behind him. Further, because the IPR is a conditioned reflex, it will be elicited by the trigger stimulus and begin immediately (e.g., about 200ms) after onset of an auditory trigger (Dozier et al., 2020). For a single trigger (e.g., a sniff), any physical response occurring after the trigger stimulus stops is likely a defensive motivational system response, a physiological response to strong emotions, or other responses described in phases three and four. Finally, the IPR may be experienced without the emotional response or precursors of fight-or-flight when the trigger stimulus is very weak. Patients’ IPR responses reported by Dozier (2015b) were often experienced without emotional distress, and participants in another study often reported having a physical sensation but no emotional response or fight-or-flight precursors (Dozier and Morrison, 2017), indicating that the physical response and the emotional response can be dissociated. Furthermore, another patient perceived tensing her jaw and fists to be her emotional/physiological response to triggers (Dozier, 2022). However, with testing, she determined her IPR was jaw tensing, and clenching her fists and jaw was part of her general physiological arousal or anger response. Dozier and Morrison (2017) provide a procedure to determine the IPR. These cases demonstrate that, because it has been understudied, what individuals report as part of the emotional response (phase three) may very well include their IPR, and therefore a thorough investigation is required.

Pavlovian conditioning and the initial physical reflex

As stated above, we propose that the IPR seen in misophonia cases develops through Pavlovian conditioning. Dozier (2015b) described four cases where the physical behavior (muscle tensing) that occurred when misophonia developed was the same as the muscles of the IPR. For example, a child who, during mealtime arguments, would stand and angrily extend both arms toward her brother. Her IPR for eating triggers was in her quadriceps, shoulders, and upper arms, which were the muscles used to stand and extend her arms. The aforementioned quasi-experimental study in which 26 individuals identified their physical sensations reported that the responses varied greatly between individuals (Dozier and Morrison, 2017). Although there may be multiple explanatory factors, this variation could indicate that responses are learned rather than developed through a common neurological abnormality, thus supporting Pavlovian conditioning as the etiology of these muscle responses to commonly occurring stimuli. Further support is provided by reports of individuals who developed muscle responses to a pager (Dozier et al., 2020), chemotherapy pump (Dozier and Morrison, 2017), and phone ring tone (Dozier, 2015b). One individual reported developing a new trigger to a sound that was paired with a trigger during an experimental treatment, where the initially neutral stimulus (a ‘ping’ sound) elicited the same IPR as the trigger (Dozier, 2015b). Additionally, spontaneous recovery has been reported in connection to treatments that reduced the IPR (Dozier, 2015b). Given that spontaneous recovery is a well-documented characteristic of conditioned reflexes (Catania, 2013), these findings support Pavlovian conditioning as the origin of the IPR (Dozier, 2015a, 2015b, 2015c, 2022).

Sometimes we understand the development of the IPR as a response to a truly US (e.g., yelling at a meal) causing a startle response (UR) which is paired with the sound of chewing, so that chewing sound becomes the CS, and the startle response becomes the CR (IPR). Furthermore, we also see potentially second-order classical conditioning examples, where emotional responses develop through recurrent conditioning events. We argue that emotional responses (e.g., concern, offense, worry) often include individual unconscious physical responses (e.g., one person may raise their shoulders, while another person tightens leg muscles). The unconscious physical component can then become associated over time with the sounds of a parent, sibling, or partner, so that the sound becomes a CS that elicits the CR (IPR). For example, a child may acquire a reflexive or consistent unconscious muscle response to a parent’s scowl (e.g., they hold their breath). If the parent scowls when hearing a chewing trigger, then the child will hold their breath and could develop a hold-breath reflex response (IPR) to that sound. We emphasize that this is a conditioned physical reflex (i.e., muscle tensing) and not a conditioned emotional reflex. However, we propose that a conditioned emotional reflex does develop, and this is described in phase three.

For the purpose of this manuscript, a response is any form of behavior. A response can either be a reflex response elicited by a specific stimulus or an operant response evoked by a stimulus and learning history (i.e., operant conditioning). A conditioned (learned) reflex response occurs immediately when the stimulus is perceived, without thought. A person can choose to not emit an operant response but has no willful control to prevent a reflex response. Emotions are reflexive behavior which can occur due to conditioning with a specific stimulus, or can occur due to a thoughtful, evaluative process. In this manuscript, we refer to conditioned emotional responses as those which develop and are emitted immediately upon experiencing the stimulus. Our distinction between physical and emotional reflex responses is critical. A physical reflex is a purely physical action of the body. For the IPR of this model, it is usually a skeletal muscle flinch, but it could be something else (e.g., pain sensation, sexual sensation, or goosebumps). A conditioned emotional reflex is an emotional response elicited by a stimulus with accompanying physiological responses. We always refer to physical responses from emotions as physiological responses, not physical reflexes. We consider the IPR a conditioned physical reflex and the emotional responses of phase three conditioned emotional reflexes, with accompanying physiological responses. Phase three also includes evoked operant behavior (e.g., screaming) and elicited reflexes (e.g., fight, fight, or freeze).

Stimulus-response Pavlovian conditioning

The typical understanding of Pavlovian conditioning is that learning takes place when a neutral stimulus (NS/CS) is paired with an US/UR, or for second-order conditioning, an established CS/CR, whereby acquisition of the CR is driven by the CS-US pairing (Ghirlanda and Enquist, 2019). However, with misophonia, there is usually no clear US/UR, and there have been no examples of US/UR reflexes reported in the misophonia literature. Interestingly, an alternative understanding of classical conditioning emerged in the mid-2000s, known as stimulus-response (S-R) Pavlovian conditioning, which has direct application to misophonia. S-R Pavlovian conditioning proposes that a response develops due to an association between the NS/CS and the physical response. For example, Donahoe and Vegas (2004) reported an S-R association in the muscle response of pigeons swallowing. The stimulus-to-response delay from water-into-mouth (US) to swallowing (UR) was a half-second. With this delay, the researchers tested forward and backward conditioning of the CS to the US (water-in-mouth) and to the UR (swallowing). Forward conditioning (CS before both US and UR) reliably developed a condition response, while backward conditioning (CS after both the US and UR), as expected, did not. However, backward-to-US and forward-to-UR (CS after the US and before the UR) reliably developed a CR. The study concludes that it is the CS-UR, or S-R, relationship that is critical to the development of a conditioned muscle response. Therefore, a US/UR reflex is not required. All that is required is a consistent pairing of a stimulus and a response.

The S-R view of Pavlovian conditioning is consistent with the neurology theory that the brain attempts to minimize expectation error by predicting responses based on prior experience, and thus tensing the muscle following the stimulus (Haruno and Kawato, 2006; McClure et al., 2003). In S-R Pavlovian conditioning, when a stimulus is predictably followed by a muscle response the stimulus becomes a CS and the muscle tensing becomes the CR. Note that the muscle tensing response must predictably follow the stimulus, but an US is not required to develop a S-R Pavlovian-conditioned reflex. Unfortunately, to date there are no published studies of S-R Pavlovian conditioning, either in animals or humans; nor are there any studies confirming or refuting the findings of Donahoe and Vegas (2004). This is clearly a research opportunity, so we only have case data for S-R conditioning in humans.

For example, in a case referred to above, a trauma center surgeon developed a shoulder flinch response to his pager (Dozier et al., 2020). The surgeon stated that when the pager initially sounded, he felt a sense of dread about what gruesome injury he might face in the trauma center. With the dread emotion, there was a slight physical response (i.e., shoulder tensing). With repeated pairing the CR developed and strengthened into a shoulder muscle jerk, and every time his pager went off (CS), his shoulders flinched (CR), until he changed jobs and stopped carrying a pager.

S-R Pavlovian conditioning of a muscle response has direct application to our assertion of how misophonia develops and why the misophonic response strengthens with typical exposure to trigger stimuli. We begin with an explanation of how the IPR develops. When a particular person perceives a common stimulus (e.g., chewing sound) and consistently has a thought with an accompanying specific muscle tensing (e.g., biceps), the chewing sound becomes a CS/trigger that elicits the tensing of the biceps (CR/IPR). For example, a person could hold their breath when hearing eating sounds they deem inappropriate. This results in a temporal pairing of eating sounds and breath holding. The eating sounds would become the CS/trigger and breath holding would be the CR/IPR. This could describe the development of a person’s first misophonia trigger or a subsequent trigger that is unrelated to previously developed triggers. The stimulus and the response are likely mediated by a negative thought or emotion. Patients report varied situations in this regard. Possible scenarios include an unconscious behavior unrelated to the stimulus, such as the child struggling to breathe due to asthma (Dozier 2015a); annoyance, such as sound emanating from a neighbor’s property (Ferrer-Torres and Giménez-Llort, 2021); someone breaking etiquette rules, such as chewing loudly; or a sense of unfairness, such as being criticized for chewing loudly, but then hearing a sibling chewing. Indeed, there are numerous possibilities for a sound and negative thought to result in an unconscious muscle response that could enable the development of a Pavlovian-conditioned muscle response. Thus, the natural occurrence of a stimulus, followed by a specific muscle response, can easily develop a trigger/CS with a CR/IPR of that specific muscle.

Individual differences in perception of events and responsiveness to stimuli may cause one person to respond to a stimulus when others do not. Wu et al. (2014) reported a strong association between misophonia impairment and general sensory sensitivity, and moderate associations with anxiety, depression, and obsessive-compulsive symptoms. Additionally, individuals with anxiety display an attentional bias towards threatening stimuli (Cisler and Oster, 2010). Similarly, Fox et al. (2002) reported a correlation between heightened trait anxiety and increased attention to emotional facial stimuli. Thus, individual differences in awareness and responsiveness to common stimuli and family dynamics can cause one child to develop a misophonic trigger in response to common sounds but not their sibling.

Strengthening of the initial physical reflex

We will next consider how misophonia triggers can strengthen. We propose that the IPR strengthens with typical in vivo exposure to triggers. With S-R conditioning, once the ANS has developed the CS/CR reflex, every experience of the CS (which includes context) creates an S-R conditioning learning event. When the CS is detected, the CR is elicited. If there is no additional response in the CR muscle, it creates an extinguishing event. If there is slight additional tensing in the CR muscle, it creates a reflex maintenance event, and if there is considerable additional tensing in the CR muscle, it creates a reflex strengthening event. Note that the traditional view of reinforcement of a conditioned response has questionable application for S-R conditioning. With S-R conditioning, the theory is that the brain tries to reproduce the CS/CR reflex to match prior behavior. As the physical response is intrusive, the person may tighten the muscle of the IPR after experiencing the reflex and so it maintains or strengthens the reflex. The intense emotions of misophonia (phase three) have accompanying physical responses which may include tightening the muscle of the IPR. This is shown in Figure 3 as the feedback connection from phase three to the IPR. A trigger thus creates a conditioning event because the muscle response after the reflex is stronger than the reflex response alone. This proposition is consistent with the report that mere exposure to misophonic triggers generally increases misophonia symptoms rather than reducing them (Schröder et al., 2017). We therefore posit that typical exposure to misophonic triggers maintains or strengthens the IPR.

Expansion of trigger stimuli

Once misophonia has developed in an individual, evidence suggests that new triggers can develop in three ways: 1) independently of existing triggers, 2) by pairing with an existing trigger, or 3) though generalization of trigger stimuli. The same process that allows the first misophonia trigger to develop can allow the development of other triggers, independent of the first trigger. When a second trigger develops independently, it may have a different IPR than the first trigger, or it may have the same IPR. One study reported that 42% of the 26 people tested for their IPR had distinctly different IPRs for different triggers (Dozier and Morrison, 2017). For example, one individual reported an IPR of shoulders tensing in response to the sound of someone chewing and an IPR of fist clenching in response to the sound of someone sniffing. However, note that IPRs are not necessarily different for each trigger. A person may have a characteristic response to a stimulus they perceive as intrusive (e.g., tensing neck muscles), and therefore a new trigger that develops independently of other triggers may have the same IPR as one or many other triggers.

When a NS (new CS) is paired with an existing trigger (CS), it is also temporally paired with the existing trigger response (CR/IPR), so the new CS has the same CR/IPR as the established trigger. For example, it is common for misophonic individuals with auditory eating triggers to develop a visual trigger of jaw movement (i.e., chewing; Claiborn et al., 2020; Dibb et al., 2021; Edelstein et al., 2013; Jaswal et al., 2021; Swedo et al., 2022). By noticing jaw movement while being triggered by the sound of chewing, jaw movement becomes a CS that elicits the same CR/IPR as the sound of chewing. Once the visual trigger develops, it can maintain or strengthen even without continued exposure to the auditory trigger. An example is the woman who had auditory and visual triggers of her husband scratching his beard (Dozier, 2015a). The auditory trigger was greatly reduced through counterconditioning, but the visual trigger remained unchanged.

Finally, trigger stimuli will generalize to other settings, sources, and variations of the sound of the original trigger stimulus. Once a trigger generalizes to a new environment, source, or variation, the response will strengthen with continued exposure to the trigger. We argue that all three ways of developing new triggers are the result of natural S-R Pavlovian conditioning events that occur in typical daily life. As such, the perceived experience of misophonia is often one of ever-growing distress and dysfunction and seems to rarely subside without proper treatment.

We reiterate that while the IPR is overwhelmingly a skeletal muscle response, it can be virtually any muscle or physical response. Less common responses could be a sexual sensation, sensation of warmth, nausea, or numbness of skin (Dozier and Morrison, 2017). Additionally, our clinical experience includes IPR of pain at a specific location, sensation of burning on the skin, an itch, goose bumps, intestinal contractions, stomach contractions, and urge to urinate.

Phase three – Intense emotional response

The third phase of the model is ‘intense emotional response’. At first glance, it may seem as though this aspect of misophonia is the most understood. Indeed, intense emotional responses are the primary complaint of both individuals who suffer from misophonia and their loved ones (Brout et al., 2018; Guetta et al., 2022; Jastreboff and Jastreboff, 2002). The variety of emotional responses has been widely documented (Dibb et al., 2021; Dozier, 2017; Rouw and Erfanian 2018). There is little debate in the literature as to the many emotional experiences that overwhelm and plague individuals with misophonia. Dozier (2015b) proposed that the negative emotions develop because of the aversive and intrusive nature of the IPR. Aversive stimuli have been shown to elicit negative emotional responses. Research using rats showed an immediate aggressive response is elicited by electrical shock (Ulrich and Azrin, 1962), while research on humans indicates aversive stimuli evoke fight-or-flight emotions and overt behavior (Berkowitz et al., 1981; Berkowitz, 1983). Furthermore, aversive olfactory and gustatory stimuli were reported to elicit activation of the limbic system (Zald and Pardo, 1997; Zald et al., 1998). These studies provide plausible support for the assertion that the aversive nature of the IPR (phase two) contributes to the development and maintenance of the emotions of misophonia; however, once the IPR develops, there are many, varied emotional experiences that occur in the context of each trigger event.

Additionally, brain imaging research indicates the emotional response is a reflexive learned emotional response (Kumar, 2015; Kumar et al., 2017; Schröder et al., 2019), though no information on the temporal relationship of the emotional response and IPR is provided due to the three-second sample rate of fMRI. The anterior insula cortex, which is central to the misophonic emotional response, integrates interoceptive and exteroceptive stimuli, so the interoceptive sensation of the IPR would be included in the overall sensory experience which triggers the emotional response. The specific brain structures involved are described in the introduction, but do not include any of the brain structures identified for Pavlovian conditioning of a muscle response (Thompson, 1990). Therefore, we posit the learning of the emotional response of misophonia is separate from the learning of the IPR. Therefore, the reflexive emotional response develops due to the repeated experience of the intrusive and aversive IPR, along with simultaneous emotional experiences (e.g., conflict with the person producing the trigger or frustration from lack of control).

Though there is no published research on S-R conditioning and development of emotional responses in humans, there are three published misophonia cases where the individual experienced a weak physical response (IPR) but no emotional response with exposure to weak trigger stimuli during treatment (Dozier 2015a, 2015b, 2015c). This supports the distinct separation of the IPR and the emotional response. In the Mitchell-Dozier model, the trigger stimulus elicits the IPR (phase two), and the IPR elicits the emotional response (phase three).

The purpose of this section is not to provide new information regarding the intense emotional responses. Rather, we provide a cognitive-behavioral structure to understand these emotional responses (Tolin, 2016), a structure which is linked to current understanding in the field at large, as well as to empirically supported treatments for other commonly comorbid disorders (LeMoult and Gotlib, 2019; McHugh et al., 2009; Szkodny et al., 2014).

In our model we attempt to explain emotional responses from the tripartite model of emotions presented in the Unified Protocol for Transdiagnostic Treatment of Emotional Disorders (Barlow et al., 2018). This model presents emotions as having physical, cognitive, and behavioral components to responses (see Figure 3). From this model, we assert that the intense emotional responses reported by patients will have three vital aspects. First, we attempt to understand the intense physiological discomfort. It is important to note that while the physiological discomfort is separate from the IPR, it can present similarly. Second, we attempt to understand the unhealthy, automatic thoughts experienced by patients. Third, the intense emotional responses must also include an exploration of the strong behavioral urges to avoid the discomfort. Below, we provide a brief explanation of each of these three core components to emotional responses.

During an intense emotional response, patients will experience physiological discomfort at a level tantamount to a physical attack. Patients often report feeling as though the misophonic trigger caused pain in some capacity. The IPR of phase two is very strong in some patients. One woman described her experience of being triggered as feeling as though a “shovel was run through her sternum and out her back” (Dozier, 2015a). Many patients have a strong muscle reflex that feels like receiving an electrical shock (Dozier, 2015c, 2022). The IPR occurs with each instance of a trigger stimulus and continues for the duration of the trigger, so for a longer trigger (e.g., a single long snore), the IPR triggers phase three and both phases continue until the trigger stimulus stops. Therefore, the misophonia sufferer experiences both phase two and phase three simultaneously, often with greater intensity due to the individual’s reflexive response to the sensation of the IPR. Additionally, there is an unconditioned physiological distress response to the intense emotions (Šimić et al., 2021). Other commonly reported physical responses which occur in addition to the IPR include increased heart rate, sweating, general muscle tension, and tension of specific muscles associated with anger and distress (e.g., jaw and fist clenching; Edelstein et al., 2013; Dibb et al., 2021). The physiological discomfort cannot be emphasized enough. We have found physiological discomfort is often a primary complaint of the patient during clinician assessments. However, because the intense emotional response is not always expressed behaviorally as ‘painful’, this aspect is often underappreciated by clinicians. Patients frequently report typical ‘fight, flight, or freeze’ responses, indicating the brain perceives the trigger as threatening.

Next, it is vital to explore the unhelpful automatic thinking associated with the intense emotional responses of misophonia. Patients frequently report unhelpful thinking, such as very frequently perceiving the trigger as an ‘assault’ or an affront. Social media was used to identify thoughts in response to triggers including thinking that it is on purpose to irritate the individual, disgust, hyper-fixation on the sound, and even threats or violent thoughts (Guzick et al., under review). As such, it is understandable when patients frequently report specific thoughts regarding the unfairness of the trigger, worries about the next possible trigger, and beliefs about the intolerance of their discomfort. Further, from numerous patient encounters and interviews, we now understand it is an incredibly common occurrence for patients to ‘mentally review’ specific qualities of the trigger. While no research has examined this phenomenon in detail, we believe given the perception of the triggers being an ‘attack’, it makes sense that the brain would remember details of ‘the attacker’ (i.e., the sound). Further, the perception of the triggering event as an attack helps makes sense of the ‘hypervigilance’ patients naturally exhibit after the triggering event.

Finally, from this model, emotions are also understood to ignite an automatic motivation, known as ‘action tendencies’, to engage in some behavior related to the strong physiological and thinking responses. Action tendencies generally result in “emotion-driven behaviors” (EDBs, Carver and Harmon-Jones, 2009; Christensen et al., 2019; Lewon and Hayes, 2014). The behavior feels out of control, automatic, and incredibly difficult to resist. Examples of EDBs include orienting responses, negative facial responses, verbal demands, or physical aggression (Bossuyt et al., 2014). The application of EDBs to misophonia seems very clear on the surface as there are numerous anecdotal reports of explosive externalizing, destructive behaviors. However, when a patient with misophonia is triggered, a wide array of emotions can be elicited, and thus, a wide array of both external and internal action tendencies occurs.

Avoidance and approach are action tendencies commonly reported as instinctive responses to anger and fear, respectively, although they can both be elicited by various emotional states (Bossuyt et al., 2014; Klein et al., 2011; Sawashima, 2019). Disgust, however, an emotion commonly reported by individuals with misophonia, has the dominant action tendency of behavioral avoidance (Izard, 1993). The observed avoidance can include both active and passive features, both of which are reported by virtually all our patients. Active avoidance involves terminating exposure to the stimulus by moving away from the perceived trigger or shouting ‘stop’ at the individual performing the triggering behavior. Passive avoidance involves actions like closing the eyes or covering the ears. Approach and avoidance in various forms seem to be common action tendencies in misophonia.

With our patients, we discuss how behaviors/choices are seemingly automatic, but we try to emphasize that it is the ‘action tendencies’ or urges that are automatic, rather than the often-regrettable behaviors/choices. Doing so allows the patient to have hope that the EDBs are indeed modifiable and that the urges can eventually be resisted through treatment. Although these thoughts, urges, and EDBs occur as part of the intense emotions of phase three, they generally continue, along with the physiological distress, and become part of the coping behavior of phase four.

Phase four – Coping responses

Phase four is non-reflexive, operant behavior that occurs after the trigger stimulus has stopped plus residue of the behavior of phase three (e.g., emotions, physiological responses, and EDBs), and automatic behavior provoked by cognitions and actions after the trigger stimulus has terminated. It can be the time after a single trigger (e.g., a single sniff), the time between intermittent triggers, or the time after a series of triggers has ended (e.g., person leaves the room or puts on headphones to block triggering sound). Phase four is primarily the individual’s coping responses to intense emotional and physiological distress, including both internal (covert) and external (overt) coping behaviors. The duration of this phase can vary greatly between individuals, with one validation study of a misophonia instrument reporting the time to recover from a trigger experience and ‘feel normal’ varies from almost immediately to longer than 24 hours (Dibb et al., 2021). A key distinction for phase four is that the trigger stimulus has ceased, so the IPR and the learned emotional responses elicited by the trigger experience have ceased. However, the physiological distress and intense emotions do not instantly cease, thus they continue into phase four.

Internal coping strategies are primarily a mental review of the specific nature of the trigger, anger rumination, and thoughts associated with the many possible misophonia emotions, including ways to escape the trigger. Patients regularly report a prolonged mental review of the misophonic trigger as though it were an attack, which reinforces the belief that the next trigger will be intolerable and must be avoided, thus strengthening the anxiety and avoidant behaviors of phase one. Research suggests that anger rumination, which has been identified as a component of other disorders (e.g., OCD), is associated with trait anxiety/negative affect rather than a specific disorder (Jessup et al., 2019). We find that the mental review of misophonia triggers often includes anger rumination. The mental review also prolongs the individual’s focus on the trigger and its source. This maintains or increases salience and responsiveness to subsequent trigger stimuli, likely strengthening phases two and three. The mental review of the trigger can cause the person to retrigger themselves, prolonging the distress and strengthening the urge to engage in hypervigilant behavior.

Widely known are the aggressive or panic-like behaviors commonly reported by individuals with misophonia (Jager et al., 2020; Rosenthal et al., 2021). One such behavior is mimicking of oral triggers sounds, for which a neurological basis has been proposed (Kumar et al., 2021). Additionally, as a method of eliminating the trigger or communicating to others in the environment that they are upset, patients commonly report they emit facial and bodily responses (e.g., death stares; Guzick et al., under review). Patients often become aggressive and ‘verbally snap’ or ‘verbally assault’ the person making the trigger. In some cases, patients, usually children, become physically violent. While these overt behaviors generally succeed in stopping the triggering behavior, they can also create undesired consequences.

Phase five – Environmental response and consequences

Phase five includes the internal and external consequences that result from coping behaviors. Internal consequences include beliefs and new emotions based upon environmental responses to anger and panic; for example, the development of emotions such as shame and guilt (Jager et al., 2020), and beliefs regarding how ‘intolerable’ the trigger is (Guzick et al., under review). Further, explosive anger or panic can produce consequences from others; namely, they try to stop the trigger.

Parents of children with misophonia can unintentionally reward explosive behavior by terminating the trigger; however, parents often blame the child for being ‘out of control’ or being ‘dramatic’. Parents and partners of individuals with misophonia report ‘walking on eggshells’ or ‘being controlled’ by the misophonic individual (Guzick, et al., under review). But behaviorally, if screaming makes the pain stop, the individual is going to keep screaming. As such, these reactions from others, which seemingly accuse the patient of a deficit of character, are actually maintaining or increasing the explosive behavior. These environmental consequences shape the operant behavior in phase four and, though much of the behavior in phase three is reflexive or automatic in nature, consequences shape the operant behavior of phase three (e.g., emotion driven behaviors). This effect is shown in Figure 3 with a dotted line from phase five to phases four and three.

We often find environmental changes are necessary in order to decrease explosive behavior. Parents and loved ones must be trained to not engage in rescuing behaviors which inadvertently reward the misophonia sufferer’s explosive attempts at stopping the trigger. Further, we find that training parents and loved ones to properly view misophonia as an illness can help to decrease responses which cause guilt and shame in the sufferer.

Environmental changes (putting in ear plugs or moving to another location) also function as a reinforcer because they allow the patient to escape the trigger stimulus. The reduction in exposure to the trigger is a reinforcing consequence for the overt behaviors and so the patient continues to emit these behaviors. Unfortunately, due to the prolonged duration of phase four, simply stopping the trigger may not alleviate the negative effects from being triggered, which can persist for an extended period of time, sometimes even continuing into the next day (Dibb et al., 2021).

The misophonic response to triggers is a repeating cycle, whereby each phase strengthens both the previous and subsequent phase. As noted earlier, phases two to five contribute to the creation of an aversive emotional and physical experience, and can increase the sufferer's belief that the trigger experience is simply intolerable. This view of the misophonic experience as being intolerable increases hypervigilance, anticipatory anxiety, and avoidance, which is phase one of the Mitchell-Dozier model.

Clinical implications

We assert that misophonia is a chronic illness which must be continually managed, but we do not propose a cure. We view misophonia as a result of a normally functioning neurological process (i.e., Pavlovian conditioning). Because misophonia is a conditioned response, even when all symptoms extinguish, the patient remains vulnerable to developing new triggers or the reemergence of prior triggers. A brain imaging study (Kumar et al., 2017) reported that, compared to control participants, misophonia individuals had higher activation in brain areas responsible for emotional responses when exposed to unpleasant sounds, possibly indicating that a person with misophonia is more responsive to sounds deemed unpleasant and therefore more likely to develop a misophonia trigger. CBT for misophonia emphasizes the importance of not only extinguishing triggers, but continuous practice of techniques as well as altering vulnerability factors when and where possible. Further, the importance of meaningfulness and quality of life is utilized to cope with accepting the reality of a chronic illness and providing motivation for consistent management.

As with other CBT theoretical models of pathology development, the Mitchell-Dozier model is directly linked to misophonia treatment, presently called “cognitive-behavioral therapy, misophonia” (CBT-M, second author) and “relaxation and counterconditioning therapy” (RCT, Dozier, 2022). Utilizing the Mitchell-Dozier model, CBT-M and RCT treatments have shown promising results in our practices, though there is a lack of scientific study of these treatments. Both therapies incorporate intensive progressive muscle relaxation training and counterconditioning. This model elucidates two important aspects of the nature and features of misophonia which are poorly understood implications for treatment: the Pavlovian response of phase two and the mental review of phase four. Within clinical settings, many patients report significant reduction in misophonia severity when the Pavlovian response is treated directly through behavioral techniques as reported in three case studies (Dozier, 2015a, 2015c, 2022). Additionally, patients often report increased quality of life by learning to address mental review, which is a newly identified feature of misophonia observed within our clinical practice.

Alternative explanations

It is important to acknowledge that additional independent research is needed to validate this model and the effects of each phase as discussed above. It is possible that the phases of misophonia shown in this model may not have the causal effects we have ascribed to them. For example, the IPR may not be present in all misophonia cases. Furthermore, if the IPR does exist in all cases, it may simply develop as a result of repeated negative emotional responses to the trigger (i.e., phase 3 develops first, then phase 2). Alternatively, the IPR may occur simultaneously with the emotional response rather than preceding and eliciting the emotional response, or add to the overall negative misophonic response, but not be germane to the development and maintenance of a misophonia trigger. We propose that the IPR is an integral part of the reinforced learning of misophonia, but there may be other, yet unknown factors that are responsible for the reinforced learning of misophonia. While our clinical cases appear to confirm that the IPR is integral to the development and maintenance of misophonia, more research is required to confirm that the IPR is not simply another symptom of misophonia.

Possible broader implications for an IPR

We speculate other conditions may sometimes include a reflex similar to the IPR of misophonia. A physical reflex elicited by a phobic stimulus may contribute to the phobic response and maintenance of the phobia. Similarly, a physical reflex might contribute to other conditions such as PTSD, tinnitus, or anxiety. As this is currently unexplored, it may be an important part of other disease processes. Furthermore, the IPR may be a factor supporting the James-Lange theory of emotion (Cannon, 1987), which proposes that emotions are the result of physiological arousal.

Research opportunities

This model identifies the need for basic research on stimulus-response (S-R) Pavlovian conditioning and applied misophonia research. S-R Pavlovian conditioning theory was experimentally demonstrated by Donahoe and Vegas (2004) and has numerous citations. Also, crucially, we find no rebuttals of S-R Pavlovian conditioning theory, and no research studies refuting the findings. One supporting study focused on the role of responses in Pavlovian acquisition and reported that the datasets they analyzed support the response-dependent model, in which CR acquisition is based on the occurrence of the CR rather than the CS-US experiences (Ghirlanda and Enquist, 2019). Still, fundamental research on S-R conditioning is needed. Research opportunities include investigating the commonly reported learned reflex response to pagers. With the advent of the pager smartphone app, a surgeon can change the alert tone regularly to prevent the development of a conditioned response. This may allow real-life data to be collected on the acquisition of a CR to a repeating, innocuous stimulus. Additional study opportunities include cancer patients’ response to their chemotherapy pump, and study participants’ response to a unique sound that indicates an aversive consequence. This may help us understand how everyday life activities allow misophonia to develop.

Application of this model to applied misophonia research may be even more important. Several studies have reported success in reducing misophonia severity using CBT techniques (Frank and McKay, 2019; Jager et al., 2021; Lewin et al., 2021; Schröder et al., 2017). Specific components of reducing the IPR and covert mental review may be added to existing protocols to determine additional treatment benefit. Several case studies indicate that reducing the IPR, even when there are comorbid conditions, can reduce misophonia severity (Dozier, 2015a, 2015c, 2022).

We recommend misophonia treatment studies assess participants’ IPR, because muscle response IPRs (e.g., shoulder flinch) contribute to effective treatment after appropriate muscle relaxation training (Dozier, 2022), whereas others (e.g., sexual response or intestinal constriction) have made treatment difficult or impossible because these responses cannot be willfully controlled and they are very aversive. This may be an important variable to help understand differences in individual response to treatment. The method of determining the IPR is described by Dozier and Morrison (2017) and can be aided by the free Misophonia Reflex Finder app (https://apps.apple.com/us/app/misophonia-reflex-finder/id983574804).

We recommend independent research to validate the existence of the IPR of misophonia, which to date has only been identified by Dozier and his collogues. Dozier and Morrison (2017) report varied IPR sensations in a sample of 26 individuals. This supports the existence of somatic responses to misophonic triggers, but it does not show the temporal relationship in the misophonic response chain, and it relied on self-report of participants. Therefore, this study needs to be replicated and expanded. There are likely other ways to validate the existence of the IPR as a typical component of the misophonic response.

Research on the timing of the trigger stimulus, IPR, and emotional response could increase our understanding of the underlying reflex responses that cause the misophonic experience. A pilot study reports an interstimulus response (trigger to IPR) of 200ms for auditory triggers and 350ms for visual triggers (Dozier et al., 2020). Studies investigating the misophonia emotional response using fMRI have a sample time of 3 seconds, so we currently have no data on the relationship between the muscle response of the IPR and the misophonia emotional response.

We recommend experimental evaluation of treatment protocols based on this model. The uniqueness and simplicity of the Mitchell-Dozier model can provide many opportunities for a wealth of research into the nature and features of misophonia.

Finally, we acknowledge the difficulty of conducting research on the IPR. Our experience and Dozier and Morrison (2017) indicate the physical response of the IPR is different in each person. Therefore, a group study with electromyography contacts on specific muscles or a brain imaging study would likely not show the individualized physical response of each person. Additionally, many responses may be difficult to empirically detect due to the muscle being deep in the body, or for bodily sensations such as feeling numb or a flash of warmth. Furthermore, studies on the IPR and our clinical tests relied predominately on self-report, which has inherent reliability concerns. Even though research on the IPR may be challenging, the significance of such a feature of misophonia makes it worthy of investigation.