As outlined in section 3, the negative emotional arousal itself is hypothesized to be included in the associative fear structure and to reactivate representations of other elements within the structure. This reactivation might in turn ignite the whole network’s activation due to strong interconnections (Elbert et al., 2006). In conclusion, (particulary negative) emotion processing is considered to be crucial in the current dissertation.
The following paragraphs describe some basic assumptions about emotion processing. Afterwards, an overview concerning empirical studies on the processing of affective material is given for paradigms that are comparable to the below described studies. The presentation of previous evidence starts with a summary of studies among healthy participants, followed by some examples among other clinical samples and some first experimental trials among PTSD patients.
A brief summary of emotion theorizing as basis for processing of affective material
“A key function of emotion is the preparation for action” (Schupp, Junghofer, Weike, & Hamm, 2003, p.7). A variety of particular emotional processes emerges in central and peripheral nervous systems when an individual is confronted with motivationally relevant stimuli (e.g. Balliel, 2002; Cuthbert et al., 2000; Keil et al.,
2001; P. J. Lang, Greenwald, Bradley, & Hamm, 1993). The biphasic emotion theory (P. J. Lang, 1979) proposes that these processes are related to two basic action dispositions, which are underlying every motivational behavior: a defensive/aversive and a consummatory/appetitive action disposition. A brief overview in the categorization of emotion theories is given in the next paragraphs in order to enable the embedding of the biphasic emotion theory in emotion theories in general.
Emotion theories have a very long history. Initial theorizing dates to Plato and Aristotle 400-300 years before Christ. The history of emotion theory is accompanied by several long lasting debates. While Plato postulated a separation of the mind into cognition, emotion, and motivation, Aristotle claimed that these processes are not distinguishable. Plato’s idea later found a prominent advocate in Descartes (17th century) who proposed the dualism of mind and matter. Descartes understood the body as a machine with material properties like extension and motion. The mind was conceptualized as nonmaterial entity that does not follow physical laws. Both mind and body were assumed to have a reciprocal influence on each other. Emotions were imagined as conscious perception of the mind about processes within the body. This relationship between perception and physical changes is also found in William James’s (1884: “What is an emotion?”) and Carl Lange’s (1885: “Über Gemüthsbewegungen”) assumptions: Both authors independently claimed that emotion consists of perceptions of different visceral (James) or vasomotoric (Lange) changes. The body in turn reacts to changes in the environment and individual experiences. This early theory was mainly based on introspection and accounts particularly for some emotions that involve physical reactions such as anger, joy, and fear. In the early 20th century, Walter Cannon and Philip Bard were very engaged in proving the James-Lange-theory to be wrong.
Briefly, they criticized the role of visceral processes in several respects: first, the distinction of viscera and central processes, second, the long time course of visceral processes, third, the uniformity of visceral processes in different emotions, and fourth, the failure in provoking emotions by prompting visceral processes (Meyer, Schützewohl, & Reisenzein, 2001).
In more recent emotion theorizing, a new debate emerged: the distinction between categorical and dimensional theories.
Categorical theories continue Charles Darwin’s hypothesis of specific, congenital emotions that are each characterized by a specific activation pattern in face and behavior. Categorical emotions theories claim that emotions consist of several basic
emotions. Basic emotions itself are those that cannot be derived from other emotions.
Within the long history, several authors (e.g., Schmidt-Atzert, Plutchik, Ekman, Tomkins, Izard) proposed different basic emotions that are still assumed to be elementary and congenital and can be identified by biological and physiological elements. Examples for basic emotions are fear, anger, joy, sadness, trust, disgust, and surprise.
Dimensional theories are based on Wilhelm Wundt’s idea: Wundt proposed three dimensions of tension-relaxation, pleasure-unpleasure, and activation-inhibition.
Emotions result from their specific value on several dimensions. But as the basic emotions vary in the categorical approach, the assumed dimensions vary, too. The dimensional conceptualization was inspired by Osgood’s studies (1957) who extracted three dimensions from studies with the semantic differential (see below) for pairs of antonyms: evaluation, potency and activity. These initially postulated dimensions have been further developed by other authors. Lang (1979) initially proposed the three dimensions, too. Substantial evidence led to Hamm and Vaitl’s (1993) conclusion that the third dominance dimension has no additional predictive value in describing a certain stimulus. Hence, the general practice emerged in describing a stimulus by the remaining two dimensions: A vector space is spanned by means of the valence and arousal dimension. Within this vector space, all kinds of stimuli are arranged in an u-shaped manner (Lang, 1995). A lot of research has been done for verbal stimuli basing on the words’ position in this vector space. The biphasic emotion theory (P. J. Lang, 1979) emanates from the dimensional approach, too, and will be described in more detail.
The biphasic emotion theory
The biphasic emotion theory (bio-informational theory of emotional imagery, P. J.
Lang, 1979; P. J. Lang, Bradley, & Cuthbert, 1998; P. J. Lang et al., 1993) claims that emotional responses are organized in a two-dimensional space along two strategic dimensions. First, a valence dimension relates to variations on the level of the two motivational systems (action dispositions) and therefore regulates the direction of behavior: aversive vs. appetitive behavior. The second dimension “arousal” adds a component influencing the emotional behavior with respect to the intensity. Both action dispositions (aversive and appetitive) are seen as primitive motivational parameters, involving subcortical brain centers, that lead an organism to a general disposition to approach or avoid a certain stimulus (P. J. Lang, Bradley, & Cuthbert, 1990). The
motivational parameters additionally regulate the individual’s attention (motivational attention, e.g. Öhmann, Flykt, & Lundquist, 2000). The position on the dimensions of valence and arousal reflects the motivational state elicited by a stimulus, postulating a correlation between brain state and subjective evaluation. The specific emotional response to an affective stimulus is therefore modulated by the two motivational parameters. Its function comprises the activation of associated instrumental behavior to start defensive/aversive or consummatory/appetitive strategies. Particular emotions are understood as part of a behavioral pattern, prompted by the motivational systems.
The accessibility of the biphasic emotion theory to empirical research
The relationship between valence/arousal and affective processing indicators has been studied in a wide range of response components: e.g., behavioral responses, facial expressions, autonomic responses, as well as reactivity on neurophysiological level (e.g.
Cuthbert et al., 2000; Hamm & Vaitl, 1993; P. J. Lang et al., 1993).
Affective evaluation is usually operationalized as subjective rating on a Likert-scale with respect to pleasant- or unpleasantness, or the subjective arousal level. This kind of investigation was initiated by Wundt’s historical studies in the early 1900s and by research on affective language. The latter has repeatedly shown that “the principal variance in emotional meaning is explained by two factors: pleasure and arousal” (P. J.
Lang et al., 1993, p.261). Today, there is vast consensus that specific moods and emotions can be defined by their position in a coordinate system with these two axes.