Motivation and emotion/Book/2017/Emotional chills

Overview
What are emotional chills?



Emotional chills refers to a set of bodily sensations, commonly experienced as shivers or goosebumps. Emotional chills (often termed "chills") are often distinct, and involve stimulation of the body's psychological and physiological systems. They are often perceived as positive experiences, however they can also be elicited by stimuli which is perceived as negative. Studies have examined the chill reactions of individuals in response to music and found that chills are indicators of peak emotional states, comprising of subjective feelings and and physiological arousal (Grewe, Kopiez & Altenmüller, 2009).

{Which of these is most true?} - (A) Emotional chills are caused by one form of stimulation; Emotional chills can be caused by positive affect - (B) Emotional chills are caused by one form of stimulation; Emotional chills can be caused by negative affect - (C) Emotional chills can be caused by many forms of stimulation; Emotional chills can be caused by positive affect - (D) Emotional chills can be caused by many forms of stimulation; Emotional chills can be caused by negative affect + (E) C and D '

Early research
Kurt Goldstein, a German Neurologist and Psychiatrist, was the first researcher to study the phenomenon of chills. Goldstein challenged the notion of localised functioning in the brain, and in WW2, began designing and implementing rehabilitation programs for brain-injured soldiers who had returned from war with the aim of developing their productive output (Pow & Stahnisch, 2013). In 1930 he accepted the chairmanship of the neurology clinic at the academic hospital in Berlin. Soon after, Goldstein was arrested by the Nazi government for promoting his holistic views. Goldstein was eventually released, and migrated to the USA, where he began exploring aphasia, and the phenomenon of chills. Goldstein created a survey aiming to uncover the the most common elicitors of the chills, and found that musical passages topped the list. Movie scenes, and breathtaking nature were found to be the second most likely elicitors of chills (Pow & Stahnisch, 2013). Goldstein died in 1965 after falling and subsequently suffering from aphasia, a condition which he heavily researched.

Many critics of Goldstein's suggested that he searched for a general psychological function which could explain a number of psychological symptoms, and therefore his findings were quite generalised. Critics also highlighted Goldstein's over-reliance on the biological model of psychology, when explaining psychophysiological processes (Noppeney & Wallesch, 2000).

Causes of emotional chills
Emotional Chills can be elicited by the stimulation of a number of sensory inputs (Grewe, Katzur, Kopiez & Altenmüller, 2010). A study published in 2010 presented evidence that Emotional Chills can be elicited through aural, tactile, visual, and gustatory stimulation. Interestingly, the study also found that emotional chills were able to be elicited by mental self-stimulation. Researchers measured the physiological responses such as heart rate, skin conductance and breathing rate, of 36 participants. Chills elicited by each of the mentioned sensory domains possessed physiological correlates (Grewe, Katzur, Kopiez & Altenmüller, 2010).

Aural Stimulation
Aural stimulation is any stimulation via the ear, or sense of hearing. Aural stimulation has been found to be the most frequent elicitor of chills by Kurt Goldstein, and has been commonly used in chills research. A number of studies have explored the efficacy of music in eliciting chills, by manipulating participants affective perception of the given music. Music with emotional and meaningful memories attached to it has been found to be more effective in endorsing chills (Pow & Stahnisch, 2013).

Visual stimulation
Visual stimulation occurs via sight, or the sense of vision. Kurt Goldstein identified visual stimuli, such as breathtaking scenery and movie scenes, as the second most common elicitor of chills. Although scenery and movie scenes generally involve aural components, chills can be elicited in the absence of sound. Similar to aural stimuli, visual stimuli which has emotion and meaning attached to it, is much more effective in evoking chills (Hain & Linton, 1969)

Gustatory Stimulation
Gustatory stimulation involves the sense of taste. The exposure to the taste and textural properties of food elicit a number of responses within the body. The temporal region of the brain has been highlighted in relation to the neural gustatory response. This suggests that the stimulation is determined by frequency of stimulus absorption, and not by the amount of the stimulus consumed (Heck & Erickson, 1973).

Mental self-stimulation
Lastly, research shows that chills are elicited frequently through mental self-stimulation. Types of self-stimulation included recalling pleasureful and emotional memories and thoughts, as well as musical pieces (Bader, 2013).

{Goldstein identified which form of stimulation as the most common elicitor of emotional chills? - Emotional + Aural - Gustatory - Tactile - Visual
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Psychophysiological processes of emotional chills
The SNS is part of the bodies autonomic nervous system (ANS), and is responsible for altering physical aspects of the body in order to engage in the "fight or flight" response. This can be achieved by a number of physical modifications including accelerating the bodies heart rate, increasing blood pressure, and even perspiring (Mori & Iwanaga, 2017). Empirical studies have indicated that emotional chills induced by music, are coupled with an increase in electrodermal activity (EDA) due to activation of the sympathetic nervous system (SNS). Furthermore, studies have shown that chills are associated with enlarged pupils, which strengthens the notion that chills are related to the SNS (Mori & Iwanaga, 2017).

Physiological responses through the pursuit of and engagement with auditory and visual stimuli engages the same reward areas of the brain which are activated in response to basic sensory pleasures. These sensory pleasures include food, drugs and even sex. Currently, the neural link between sensory pleasures and aesthetic responses such as the chills, remains unidentified. Researchers have used music as a link of pleasure and reward, as it has been important and prevalent throughout the history of all civilisations. Music is often regarded as one of the most enjoyable human experiences, and can cause a wide variety of physical and mental sensations such as feeling moved, having a dry throat, or experiencing chills. Previous research has linked the experience of chills to changes in psychophysiological measures of skin conductance and heart rate. Neural activity in the areas of the brain associated with reward such as the nucleus accumbens, and the medial prefrontal cortex have been explored (Salimpoor et al., 2013).

Although reward systems are engrained in every human, not everyone experiences intense responses to music. Individual experiences are so different that some report the inability to experience pleasurable responses to music, despite reporting positive responses to other rewards. Increased functional connectivity between the auditory cortices and mesolimbic reward circuitry areas of the brain has been identified in listening to music which is deemed pleasurable (Salimpoor et al., 2013). Despite this, it still remains unclear as to why these neural circuits evoke pleasurable physiological responses in some, and not others.

Neuroimaging techniques
A number of different brain scanning techniques are used to measure the neural processes of a multitude of responses. Below are some techniques which have been used to measure neural activity in response to music.

Positron emission tomography (PET)
PET scans measure molecular function and metabolic actions. This is achieved by injecting the patient with a radioactive glucose, and then tracking the liquids movement throughout the body and brain. PET scans have been used to survey neural activity in the paralimbic brain regions, which are associated with moderately unpleasant emotions. Such regions include the parahippocampal gyrus, orbitofrontal and the subcallosal (Blood & Zatorre, 2001). A study using PET scans was conducted to identify the primary mechanisms involved in greatly pleasurable and emotional responses to auditory stimulation, in this case, music. The examiners measured cerebral blood flow changes in brain regions associated with reward and arousal such as the ventral striatum, midbrain, amygdala, orbitofrontal cortex, and ventral medial prefrontal cortex. These areas of the brain are also involved in other pleasurable experiences like eating, having sex, and consuming drugs (Blood & Zatorre, 2001).

Diffusion Tensory Imaging (DTI)
A study published in 2016 used Diffusion tensor imaging (DTI) to examine the structural connectivity of the brain in relation to sensory and reward systems. It was hypothesised that structural connectivity between auditory - and reward - processing areas would bring on physiological responses to music. By using DTI, the researchers aimed to compare the neural activity of those who responded aesthetically, and those who didn't. 237 people completed an online survey which assessed their background in engaging with music, which was sent to various community and university emails throughout Boston, United States. To operationally define personality and music preference, the 10-Item Personality Measure Index and Short Test of Musical Preferences (STOMP) were used respectively. The experiment surveyed 20 participants consisting of 12 females and 8 male (Sachs, Ellis, Schlaug & Loui, 2016). The average age of the group was 21.6 years, with ages ranging between 18 and 34. 10 participants scored six or higher on a seven-point scale on all items in the Aesthetic Experience Scale in Music (AES-M) and were named the "chill group". The remaining 10 participants scored on average two or fewer on the AES-M. The two groups were matched on years and age of onset of musical training, IQ and personality traits. The researchers hoped that by controlling for cofounding factors, they would be able to gain an accurate understanding of the neurobiological differences in aesthetic responses to music.

The researchers engaged held a large-scale screening, where individuals ' emotional responses to music, measures of personality and background of engaging in music were measured. Emotional responses to music were measured on a 10-point scale (0 = neutral/no pleasure, 10 = high pleasure). During each musical exert, the participants were asked to press and hold the spacebar on a keyboard when the chill occurred, and hold it for the entirety of the experience. This method of data collection was chosen as previous literature has shown that pressing a button does not elicit significant physiological responses. Inter-beat intervals (IBIs), an inverted measure of heart rate, and Skin Conductance Response (SCR) were measured throughout the experiment (Sachs, Ellis, Schlaug & Loui, 2016).

As there was only 20 participants, nonparametric statistical tests were used for analysis. Participants in both groups provided higher pleasure ratings when listening to their favourite music pieces as compared to neutral control pieces. All 10 of the participants in the chill group experienced at least one chill during the musical exerts of their choice. When compared to baseline levels, those in the chill group showed a decrease in IBI, and a significant increase in the average SCR during moments which were rated most highly. Using diffusion tensor imaging, a fractional anistropy (FA) image was taken for each participant. Researchers confirmed that those in the chill group exhibited significantly higher levels of stimulation in both hemispheres of the brain, when compared with the no-chill group. The channels of white matter in the brain which were deemed to be parts of the uncinate fasciculus and the arcuate fasciculus (Sachs, Ellis, Schlaug & Loui, 2016). The arcuate fasciculus is known to be larger the left hemisphere, however the results were consistent across both hemispheres of the brain. This suggests that both hemispheres play an important role in eliciting chills.

Personality and individual differences
A group of researchers examined the factor structure, elicitors, trait antecedents and consequences of the chills using a number of studies. In the first study, participants were asked to describe what it means to get the chills, and to choose a term which best described the physical sensations of the chills (Maruskin, Thrash & Elliot, 2012). A cluster analysis of the responses revealed 4 secondary clusters (tingling, shivers, coldness, goosebumps), and 2 primary clusters: "goosetingles" and "coldshivers". A factor analysis was conducted on questionnaire data, and the results supported the primary and secondary factors which were described from the participants in the preliminary study. The data indicated that goosetingles were aniticipated by approach-related traits such as extraversion. In contrast, coldshivers were predicted by avoidance related traits like neuroticism. Narrative data on the sensations was collected, which once again supported the goostingle and coldshiver structure. Upon examining the narrative data, it was found that experiencing goosetingles was coupled with greater feelings of awe, surprise and enjoyment than coldshivers, which were found to be more associated with feelings of fear, disgust, and sadness (Maruskin, Thrash & Elliot, 2012).

An analysis of diary data extended the notion further, by suggesting that goosetingles were associated with positive affect and coldshivers with negative affect on interpersonal closeness. The researchers found that by manipulating exposure to  endorse feelings of self-actualisation, they could elicit goosetingles. In contrast, exposure leading to feelings of self-annihilation elicited coldshivers. The experimenter concluded that a number of forms of evidence highlight the approach and avoidance related constructs, and that a distinction exists between the two constructs. Goosetingles and coldshivers can be understood as the physiological response which results from experiencing our deapest hopes and fears respectively (Maruskin, Thrash & Elliot, 2012).

Autonomous Sensory Meridian Response (ASMR)
Autonomous Sensory Meridian Response (ASMR) is a condition which alters ones perception of certain audio-visual stimuli which triggers intense, but pleasurable tingling sensations, similar to those described in emotional chills. These sensations are generally felt in the neck and head, and can spread to the periphery of the body. Stimuli which often trigger ASMRs are generally elicited by stimuli which are intimate in nature, and repetitive in movements or sounds such as hearing whispering or watching someone wash their hair (Fredborg, Clark & Smith, 2017).

ASMR was relatively unknown until 2010, when online users began reporting similar conditions and symptoms to stimuli. A study conducted in 2017 aimed to examine the relationship between personality characteristics and the prevalence of ASMR. The participants in the experiment were 290 adults with ASMR and 290 control group members with matching age and genders, who were recruited via online forums. Participants were asked to fill out an online questionnaire, which included demographic questions, the Big Five Inventory (BFI), the Toronto Mindfulness Scale, and an ASMR checklist. The BFI included 44 items, with 8-10 items for each of the five scales: Openness-to-Experience, Conscientiousness, Extraversion, Agreeableness and Neuroticism. The ASMR component of the questionnaire consisted of 16 stimuli which were selected based on interviews with ASMR patients prior to the experiment.

Upon analysing the results, the experimenters found that the ASMR group scored significantly higher on Openness-to-experience than those in the Control group. Although differences in this trait were apparent across both genders, the effect was stronger for Females. The ASMR group were also found to have scored higher than the control group on Neuroticism (Fredborg, Clark & Smith, 2017). ASMR participants scored lowed than controls on Conscientiousness, Extraversion, and Agreeableness. A review of the findings, revealed that repetitive sounds were the strongest and most common triggers for ASMR experiences. These findings suggest that there is a significant correlation between ASMR and certain personality traits (Fredborg, Clark & Smith, 2017).

Conclusion
Emotional reactions to external stimuli are interesting experiences as they are highly individualised, can be positive and rewarding, and can also be negative and disadvantageous. Exploring the individual differences in the reactions to stimuli may aid in furthering the understanding of the reward circuitry, which is instrumental in the onset and maintenance of emotional chills. Additionally, it may allow researchers to understand individual perceptions of peak emotional states. A clear distinction between goosetingles and coldshivers, and their respective psychophysiological responses must be made in order to more accurately describe the euphoric experience in future literature. Future research should use brain imaging techniques such as the PET and DTI to evaluate the processes involved in experiencing goosetingles, and coldshivers. Understanding this procedure would allow researchers to identify whether different mechanisms are involved in evoking goosetingles and coldshivers. The mechanisms of mental self-stimulation should be further explored. In achieving this, self-stimulation methods could be used to reach peak psychophysiological states, and treat a number of depressive disorders which are characterised by negative affect, and an absence of positive affect. Future literature should aim to uncover whether there are levels of psychophysiological responses to chills, and whether frequently experiencing chills effects the likelihood of them occurring again.