تأثیر ترس بر بیان جنبه های شبه زبانی در بیماران مبتلا به اختلال هراس با موقعیت هراسی

The present study investigated the effect of fear on paralinguistic aspects of speech in patients suffering from panic disorder with agoraphobia (N = 25). An experiment was conducted that comprised two modules: Autobiographical Talking and Script Talking. Each module consisted of two emotional conditions: Fearful and Happy. Speech was recorded digitally and analyzed using PRAAT, a computer program designed to extract paralinguistic measures from digitally recorded spoken sound. In addition to subjective fear, several speech characteristics were measured as a reflection of psychophysiology: rate of speech, mean pitch and pitch variability. Results show that in Autobiographical Talking speech was slower, had a lower pitch, and a lower pitch variability than in Script Talking. Pitch variability was lower in Fearful than in Happy speech. The findings indicate that paralinguistic aspects of speech, especially pitch variability, are promising measures to gain information about fear processing during the recollection of autobiographical memories.

Many modern psychological theories of fear have integrated a biological perspective, which resulted in multi-leveled models of fear. These models emphasize the two-fold reaction to dangerous stimuli: an immediate reaction caused by an automatically responding, conditioned system and a slightly slower reaction caused by a voluntary, more cognitive system (Brewin, 2001; Brewin, Dalgleish, & Joseph, 1996; Lang, Bradley, & Cuthbert 1998; Lang, Davis, & Öhman, 2000; LeDoux, 1995 and LeDoux, 1996). The automatically responding system induces both physiological and behavioral involuntary reactions to a dangerous situation. The second system, however, is responsible for the interpretation and attribution of the dangerous situation. A consequence of the neurologically different routes for physiological and behavioral responses, on the one hand, and higher mental responses, on the other hand, is that in acute, Fearful situations a person can, in principle, react immediately and independently from cognitive and appraisal functions. Different emotional states are characterized by specific changes in the somatic nervous systems (altered general muscle tonus and coordinated movement) and the autonomic nervous system, i.e., the sympathetic and parasympathetic nervous systems. It is beyond the scope of this paper to give a detailed description of these physiological processes, but it is evident that behavioral and physiological changes affect paralinguistic aspects of speech, i.e., content-filtered, non-semantic, non-grammatical aspects of the voice such as pitch and rate of speech (for more information see Darby, 1981 and Scherer, 1986). After all, a vocalization is the result of actions of a great number of muscles in the chest, throat and head, so any alterations in muscle tonus will affect vocal characteristics. In fear for example, increased muscle tension could lead to a high pitched voice. Likewise, changes in respiration (which produces changes in subglottal pressure) and salivation (which leads to changes of resonance characteristics of the vocal tract) have their own effect on voice characteristics. How exactly the complicated physical changes influence both each other and the voice quality is still under investigation. Because speech is influenced by immediate behavioral and physiological reactions to stressors, it reflects the main response components of the memory fear structure, i.e., the automatically responding route. When Fearful memories are recollected and recounted aloud, paralinguistic aspects of speech can reveal information about the emotional and physiological processes that take place during the recollection of that memory. Consequently, speech could be a useful tool to provide information about emotional processing of fear during exposure to Fearful stimuli. This is relevant for psychotherapy because speech is a central part of the treatment. In clinical psychology, most studies thus far have focused on the content and the organization of speech during exposure to Fearful stimuli (Amir, Stafford, Freshman, & Foa, 1998; Foa, Molnar, & Cashman, 1995; Pennebaker, 1993; Pennebaker & Francis, 1996; Pennebaker, Kiecolt-Glaser, & Glaser, 1988; Pennebaker, Mayne, & Francis, 1997; van Minnen, Wessel, Dijkstra, & Roelofs, 2002). In contrast, the physiological aspects of speech have received far less attention. To date, only two studies have focused on paralinguistic aspects of speech in clinical psychology. McNally, Otto, and Hornig (2001) investigated whether independent listeners can identify differences in paralinguistic aspects of speech. Patients with different types of anxiety disorders or with a major depressive disorder as well as healthy speakers were asked to talk about Fearful autobiographical memories and a neutral memory. Independent of the speakers’ diagnoses, the objective assessors rated the content-filtered fear memories higher on anxiety, arousal and dominance scales than the neutral memories. These findings confirm that paralinguistic aspects of speech provide information about the emotional processing during exposure to Fearful memories. However, no objective measures of the paralinguistic speech production were included, limiting the implications of the study. In addition, because the control condition consisted of a neutral memory, it is possible that the results reflected a general state of arousal in general instead of fear-specific characteristics of speech. Siegman and Boyle (1993) studied the influence of deliberate changes in paralinguistic aspects of speech on subjective mood in healthy adults. They found fear to be higher if the Fearful experiences were recounted in a mood-congruent manner (fast and loud). Several studies in speech research also indicate relationships between emotional states and paralinguistic aspects of speech (Baken & Orlifoff, 2000; Cosmides, 1983 and Scherer, 1986; Tolkmitt & Scherer, 1986). In addition, there is some evidence that paralinguistic aspects of speech provide information about the emotional involvement of the speaker in the memories he or she is recollecting (Huttar, 1968; Rice & Koke, 1981). There are various studies that demonstrate a relationship between paralinguistic aspects of speech and fear in healthy persons (Scherer, 1995; Streeter, MacDonald, Apple, Krauss, & Galati, 1983; Williams & Stevens, 1972; Williams & Stevens, 1981; or see for a review, Darby, 1981, or Scherer, 1986). Fear was found to be positively related to mean pitch, pitch range and rate of speech (Scherer, 1986). Results on pitch variability, however, were equivocal. In some studies pitch variability was found to increase in Fearful situations (see, e.g., Scherer, 1986), while in others it decreased (Scherer, 1995; Scherer & Oshinsky, 1977). In theory, pitch variability should decrease during stress as a result of higher muscular tension, which leads to an increased rigidity of the voice (Murray & Arnott, 1993; Pittam & Scherer, 1993). As fear causes extreme stress, research on the effects of other stressful conditions on paralinguistic aspects of speech is also relevant to our study (Hecker, Stevens, Von Bismarck, & Williams, 1968; Griffin & Williams, 1987). In these studies stress refers both to a negative emotion (emotional stress) and to a high workload (task stress). The comparison of stressful and non-stressful situations showed that mean pitch rises and rate of speech decreases if the stress or workload increases (Streeter et al., 1983; Williams & Stevens, 1969; Williams & Stevens, 1981). In line with the findings of studies on fear, results with regard to pitch variability were again ambivalent. In some studies pitch variability was found to increase with stress (e.g., Bergmann, Goldbeck, & Scherer, 1988), whereas in others it decreased (Brenner, Branscomb, & Schwartz, 1979; Lively, Pisoni, Van Summers, & Bernacki, 1993). A possible explanation for these ambiguous findings could be that intensity of the emotion that is experienced from the same stressor differs per person and this was not controlled for in any of the studies. Furthermore, in several studies the definitions of the various emotional states were not clear. The concepts of fear, anxiety, emotional stress and worry were used without further specification. Additional limitations of these studies are that they made use of healthy speakers or actors who simulated an emotion, possibly causing artificial emotional speech effects (exaggerated or culturally prompted). Moreover, in all studies sample sizes were very small (only seldom did the number of participants exceed ten), which makes the generalization of the results doubtful. In sum, there is ample evidence that fear can be measured in speech (Cosmides, 1983 and Scherer, 1981; Williams & Stevens, 1972; Williams & Stevens, 1981). Little is known, however, about changes in the paralinguistic aspects of speech in persons with anxiety disorders who actually experience fear, induced by autobiographical memories. The purpose of the present study was to gain more insight into fear memory processes by analyzing paralinguistic aspects of speech. To activate fear memory, patients suffering from panic disorder with agoraphobia were asked to recollect and talk about a Fearful autobiographical event associated with a panic attack. To compare the effects of real emotions to those of induced ones, in addition to talking about an autobiographical memory, the participants were asked to read aloud scripts describing likewise situations. To isolate the effects of fear from those of a general state of activated arousal, patients were also asked to talk about a Happy memory and read aloud a script about a Happy event. Paralinguistic speech parameters were measured during recollections. The research question was whether activation of fear memories could be identified by specific physiological and behavioral responses as reflected in paralinguistic aspects of speech. We chose patients with an anxiety disorder instead of healthy adults, because fear memories of mentally healthy persons are theorized to be no different than those of anxiety disordered patients. There is a difference in intensity though, in the sense that fear memories of the latter group are thought to be more easily and strongly triggered by exposure to Fearful memories. We opted for patients with panic disorder with agoraphobia because they are afraid of highly comparable stimuli and their responses to these stimuli are alike, which allowed us to control the Fearful conditions as much as possible. Paralinguistic aspects of speech were chosen, because they can provide information about immediate physiological and behavioral responses. Other commonly used physiological measures, such as heart rate and skin conductance, tend to be relatively difficult to measure, especially in a clinical environment. In contrast, speech can be more easily measured during treatment, because no wires or special apparatus on the body are necessary. This makes it a practical, and therefore, promising measure to explore, especially for clinical research into anxiety disorders. With regard to measuring emotional processing of fear, speech measures may be especially useful in those treatments in which speech is a central part of the treatment, for instance recalling Fearful memories in imaginal exposure therapies for PTSD. In the present study, the verbalized memories and script readings were analyzed and compared with respect to rate of speech, mean pitch and pitch variability. Our first hypothesis was that, because rate of speech is known to increase with increasing levels of arousal, independent of the specific emotion induced, no differences in rate of speech between Fearful and Happy utterances would be observed. In contrast, we expected that mean pitch and pitch variability would reflect differences between specific emotions. We anticipated that in Fearful speech mean pitch would be higher and pitch variability lower compared to Happy speech, as a result of increased tension of the muscles involved in phonation. And thirdly, because recollecting autobiographical memories was expected to activate the memory structure more completely and to induce more intense emotions than reading aloud a script describing comparable emotional situations, this was presumed to be reflected in the speech parameters as well.