The study of the way in which we talk impacts those we are talking to is still in its early stages. It has been suggested that 10% of conflicts that arise are as a result of difference of opinion, while the other 90% stem from the way in which these things are said (Godwhani, 2014). The study of the way in which we process emotion from another’s words is of key importance to understanding the way in which we interact, communication is a part of our everyday life. It is the basis of education, business, media and relationships. Verbal communication makes up a small percentage of our overall communication, suggesting a need for in-depth understanding of the way in which we process the information we are hearing, and its subsequent impact on emotional, behaviour and physiological responses.
Emotional prosody refers to the way in which an individual’s tone of voice is conveyed through changes in their pitch, loudness, speech rate and pauses which is different to the linguistic and semantic information (Crystal, 1986). Emotional prosody can be isolated from linguistics and interacts with verbal content, for example, sarcasm. Many sound elements play a role in this prosody, for example, one’s tone of voice may sound flat, surprised or angry for example, prosody also refers to acoustic features of voice such as pitch, loudness, stress, rhythm and pause timings. A great deal of research in this area has focused on the speed in which we are able to accurately judge the emotional content from neutral content in a voice, it was found that participants were able to process emotional content in a little as 200ms, it has been argued that this provides evidence for rapid emotional decoding (Paulmann & Kotz, 2008). There have been several proposed ways in which we as humans decode emotional prosody from spoken language, frequently these models of involve a sequence of steps, for example, extraction of acoustic cues, the representation of an auditory object, and the evaluation of emotional acoustic cues from vocal tones. It has been suggested that these decoding steps are embodied in the superior temporal and the inferior frontal cortex (Wildgruber et al., 2006), in addition to these areas it has been suggested that these steps are also represented in the subcortical structures of the brain (Wildgruber et al, 2009). Schirmer and Kotz (2006) suggested a model of emotional prosody processing which consists of different steps of information processing related to the stimulus characteristics, contextual factors, task requirements, and interindividual differences. Primarily the first step in this process includes the rudimentary processing of auditory information via the primary auditory cortex and the second auditory cortex to a lesser degree. They proposed that once this preliminary processing was complete; the secondary auditory cortices are involved in the extraction of more complex acoustic features thus allowing interpretations and classifications of this auditory information. The third step in this model suggests more intricate processing at higher cognitive levels involving anterior regions including the inferior frontal areas as well as the orbitofrontal cortex. It has been suggested that this late component could be strongly impacted by top-down factors such as requirements of the task or the context of the stimulus presentation. Instructions within a task sometimes require individuals to focus attention on the emotional information or on the other features of the stimulus and subsequently may demonstrate varying levels of the processing of emotional information from prosody. Previous research in emotional prosody has focused on brain activation during the recognition of emotional prosody, several regions have been found to be activated during this recognition process. The regions activated include the auditory cortex; an area of the temporal lobe concerned with the processing of aural stimuli (Fecteau et al 2007). The inferior frontal cortex, used in spoken and written language processing (Schirmer et al, 2004), as well as the amygdala, an area of the brain, believed to play a key role in the processing of emotions (Bach et al, 2008).). Furthermore, the orbitofrontal cortex; located in the frontal lobe and used in decision making; has been shown to be activated during recognition of emotional prosody (Ethofer et al 2009). Other regions found to be involved in the recognition of emotional prosody include the parietal and frontal cortex, believed to be involved in perception and language processing (Bach et al, 2008). Subcortical areas of the brain have also shown activation during processing of emotional prosody (Peron et al, 2010). The studies have repeatedly shown increased activation within the superior temporal gyrus (used in speech processing) as well as in the superior temporal sulcus (believed to be involved in social perception) during recognition of emotional prosody (Fecteau et al, 2007). Many have argued that the processing of emotional prosody is frequently right-lateralised (Fecteau et al, 2007). Further studies, however, have shown activation in the left or in the bilateral temporal cortex (Ethofer et al, 2009). It has been suggested that the activation of the various regions in the brain may be due to the informational input, it has been found that activation of the superior temporal sulcus and the superior temporal gyrus have shown increased activation during the decoding of angry prosody (Grandjean et al, 2005). Research into emotional prosody has shown us many variables which can impact our emotional processing. It has been found, for example, that individuals suffering from major depressive disorders, when compared with healthy controls, showed an impaired recognition of fear, sadness and happiness; when compared with healthy controls they were also found to rate fear significantly higher than when listening to anger stimuli. Participants with major depressive disorder also demonstrated a bias towards surprise rating it far higher when they heard sad or fearful stimuli (Peron, et al, 2011). Further research into the expression and perception of emotional prosody in schizophrenia showed a high level of impairment, findings that have been replicated through several studies (Hoekert et al, 2007). Further studies have shown individuals with autistic spectrum disorders have impaired processing abilities of emotional prosody (Paul et al, 2005). Many studies have focussed on the effect of Alzheimer’s on the processing of emotional prosody, research has found that as the disorder progresses the individuals’ ability to decode emotional prosody deteriorates, this deterioration has been suggested to be linked with the increasing disturbance of mood and behaviour in those with Alzheimer’s disease (Roberts et al, 1996).
From this previous research, it is evident that many factors can contribute to our ability to process emotional prosody, a great deal of previous research has focused on both age-related disorder as well as developmental disorders. The aim of this research is to focus on the way in which our ability to process emotional prosody is impacted by anxiety disorders. Anxiety disorders include, but are not limited to generalised anxiety disorder, obsessive-compulsive disorder and post-traumatic stress disorder. This study will require participants to complete a number of questionnaires to ascertain their levels of anxiety, they will then be presented with a range of verbally presented stimuli to determine their ability to process emotional prosody in this information presented.
Within this study, the intention is to develop an understanding of the way in which these disorders impact processing of emotional prosody, therefore three separate experiments will be used to study each condition and the participants ability to recognise different emotions when presented verbally. All participants in this study will require a diagnosis of either, generalised anxiety disorder, obsessive-compulsive disorder or post-traumatic stress disorder.
Primarily the first experiment in this research project will focus on individuals with generalised anxiety disorder. Participants will initially be required to complete the stait- trait anxiety inventory (Spielberger, 1989) in order to obtain an understanding of the level of anxiety experienced by the participants prior to the testing. Participants will then be exposed to a range of verbal stimuli, including a number of emotions such as anger, sadness, fear, surprise, happiness, and disgust as well as being presented with neutral stimuli. During the stimuli presentation, the participants brain activity will be monitored using in and electroencephalograph in order to establish if activity varies on correct identification of emotional prosody compared to incorrect. From this experiment the expectation is that those participants with generalised anxiety disorder will fail to process surprise correctly, instead identifying it as fear. Furthermore, it is hypothesised that these individuals will be more likely to identify disgust correctly as well as fear.
The second experiment within this research will focus on the way in which obsessive-compulsive disorder impacts the participants ability to process emotional prosody, participants in this experiment will be required to complete both a disgust sensitivity scale (REFERENCE) and a three-domain disgust scale (REFERENCE) as a measure of their level of obsessive-compulsive disorder, and a measure of their vulnerability to disgust. Once again, these participants will be presented with verbal stimuli including emotions of anger, disgust, surprise, sadness and happiness as well being presented with neutral stimuli. Once again participants will complete the activity whilst an electroencephalograph is used to monitor their brain activity, as research has shown that individuals with obsessive-compulsive disorder have decreased activity of the middle frontal gyrus and increased activity in the frontal and limbic system as well as the temporal regions associated with shame. Further to this, they show variations in the insula (associated with feelings of disgust) and the amygdala (linked to the feelings of fear associated with obsessive-compulsive disorder) (Gonçalves et al, 2016). Within this experiment, it is believed that participants with obsessive-compulsive disorder will correctly identify disgust and fear, however, will show impaired processing of other stimuli.
The final experiment in this research project will focus on the way in which post-traumatic stress disorder impacts an individual’s ability to process emotional prosody. Participants in this experiment will be required to complete both a Traumatic stress schedule (Norris, 1990) and the stait-trait anxiety inventory as a measure of their post-traumatic stress anxiety and the current level of anxiety experienced. In this condition, participants will be exposed to verbally presented stimuli expressing emotions including anger, fear happiness surprise disgust and sadness as well as a neutral stimulus. An electroencephalograph will be used to measure brain activity during the experiment, monitoring brain activity as previous studies have shown decreased activation of the amygdala and increased activation of the medial prefrontal cortex in individuals with post-traumatic stress disorder. While it has been suggested electroencephalograph, studies show limited activation of this area of the brain, traces of abnormalities on the output will be able to show if activation is present. Within this experiment, it is believed that participants with post-traumatic stress disorder will show a bias for processing anger and fear from the verbal stimuli. However, they will show impaired processing of happiness and surprise, with the belief that they may process surprise as a fear.
Overall this proposed research has many potential implications in our society, with the treatment of anxiety disorders becoming of increasing availability. This research provides a basis for increased training of healthcare professionals in both their diagnosis and treatment of anxiety disorders. With an increased understanding of the impact in the way in which our tones of voice can impact those around us; we can not only treat these conditions but potentially reduce their incidence rates through changing the way we communicate with each other in everyday life.