Common sense holds that exposure to media content can be associated with different levels of excitement and arousal. The specific case of a thrilling movie well describes the type of stimuli that come to our mind when using the terms arousal and excitation in everyday language. From a psychological point of view, arousal is conceptualized in more general terms, as a state of alertness and physical excitation elicited by external or internal stimuli, which challenge an adaptive response of the organism. The modern world is complex and rich in stimuli. It is in many respects different from the environment of our early ancestors, which required the organism to be physically prepared for immediate action, e.g., when possible threats entered the field of perception.
Although vigorous actions like “fight” or “flight” might be dysfunctional or inappropriate in the daily life of civilized humans, evolution has preserved those basic physiological alarm mechanisms, leaving the organism with a new type of adaptive task: to cope with arousal and excitation without launching atavistic behavioral programs. The narrow view of arousal as suggested by the fight–flight theory (Cannon 1914) only describes an extreme form of bodily excitation, nowadays subsumed under the term “acute stress response.” Arousal has, however, been recognized as a more universal physiological phenomenon, which is scalable along different intensity levels and which accompanies and/or influences various psychological processes relevant to the reception of communication and media content, such as attention, cognition, and emotion.
Concepts And Biological Foundations
Several terms have been used synonymously with arousal. These are activation and intensity (Duffy 1972), as well as excitation (Zillmann 1983), the latter being most often used in the sense of sexual arousal. A broadly accepted conceptualization of arousal was introduced by Lacey (1967), considering it a multidimensional phenomenon, which can be differentiated in cortical, autonomous, and behavioral arousal.
Cortical arousal is associated with the ascending reticular activating system (ARAS) located in the brainstem. It receives input from the sensory receptors and projects nonspecifically into the cerebral cortex, producing a general cortical activation. The ARAS is responsible for tonic activation (i.e., being awake, drowsy, or sleepy) as well as for phasic activation (momentary alertness). Measures of cortical arousal can be derived from frequency analysis of the human electroencephalogram (EEG). Autonomous arousal is associated with the activity of the vegetative or autonomous nervous system (ANS). The ANS consists of two antagonistic parts: the sympathetic and the parasympathetic parts. Arousal is associated with the activation of the sympathetic sub-system, while the parasympathetic part serves mainly inhibitory functions. Indicators of autonomous arousal therefore are mostly derived from peripheral measures of sympathetic activity, as, for example, from the galvanic skin response (GSR). Behavioral arousal describes the activation of the motor system, which can be observed as agitation or measured as muscular innervation using electromyography (EMG). As most research on arousal is based on animal studies, we have to be careful with the meaning of the terms. Behavioral activation is not the same as a planful action to cope with an arousing event.
Arousal And Emotions
There is consensus that emotions consist of two major components: an intensity component, i.e., the autonomous arousal (high or low arousal), and a directional component, i.e., the hedonic valence (positive or negative feelings). Schachter and Singer (1962) formulated the two-factor theory of emotion, in which arousal (or excitation) is considered the unspecific component of emotional experience, identical for all kinds of feelings and blind to their hedonic valence (pleasurable or not). Via bodily sensations, arousal is perceived by the individual and interpreted as intensity of the actual emotional state. The quality of the emotional state, however, is dependent on the cognitive analysis and the labeling of the situation. Based on this assumption, Zillmann (1983) designed his excitation transfer theory, which has broad explanatory value for various media effects. Excitation transfer theory holds that due to slower biochemical processes, the unspecific arousal part of emotions has a longer decay time than the cognitive appraisal of the situation. Thus, arousal stemming from a thrilling part of a movie can pertain and affect the intensity of joy during the happy ending. The model has also been applied to aggression as a media effect, suggesting that it is not necessarily the violent content, but the excitation effects of media stimuli, which can create the preconditions for post-receptive aggressive behavior.
Arousal and emotional valence can also be moderated by cognitive processes. By exposing participants to stressful images (e.g., a film of brutal genital surgery), Lazarus and Alfert (1964) could show that intellectualizing information can significantly reduce the level of autonomous arousal (sympathetic activation). Based on such observations, appraisal theories of emotion do not conceptualize arousal as a prerequisite for emotional experience at all and stress the regulatory functions of primary and secondary appraisal processes. These include the detection of the hedonic value of a situation as well as the judgment of the individual coping possibilities. Arousal might occur as a consequence of these cognitive processes but it is not crucial for the genesis of the emotional experience itself.
Arousal And Information Processing
In many cases communication content aims at providing information and thus primarily addresses the cognitive system of the recipient. As has been demonstrated, arousal can be an important determinant of information processing, including attention, comprehension, learning, and memory (Revelle & Loftus 1992).
A basic automatism preparing the organism for information intake and focusing the attention is the so-called orienting response, which occurs whenever the organism is confronted with a new, unexpected, or salient stimulus. The orientation response is closely associated with the activation of the sympathetic nervous system, and is characterized by a general decrease in muscle activity, an orientation of sensory receptors toward the stimulus, phasic heart rate deceleration, and an increase in electrodermal activity (Ravaja 2004). According to Öhman (1979), any stimulus is compared by preconscious mechanisms to the short-term memory. When the stimulus is classified as new, it is processed consciously. This switch from automatic to controlled processing mode is elicited by an orientation response and accompanied by an allocation of processing resources to the main channel of information processing. Stimuli that elicited an orientation response are more likely to be memorized later, which is most important for media content with persuasive intention, e.g., advertisement.
Depending on the quality of environmental stimuli, the organism has to decide whether to accept or to reject the input. The two attentional modes, environmental intake vs rejection, are reflected in specific arousal patterns (Lacey 1967). Both modes show sympathetic activation, as indicated by increased skin conductance and vasoconstriction. Heart rate, however, decreases during environmental intake and increases during rejection.
A phenomenon of particular relevance to media research is suspense, which shows the close connection between arousal and cognition (Vorderer 1996). Contrary to the orienting reaction, the arousal patterns associated with suspense are obviously derived from higher cortical areas, which are necessary for the involvement in a narrative. Suspense has been described as a state between fear and pleasure, based on expectations of bad outcome for the favored protagonist. Arousal goes along with the anticipation of a decisive point in time in the near future, where any uncertainty is reduced abruptly. The clarifying event, be it a positive or a negative outcome, leads to spontaneous relief, and a measurable drop in physiological arousal: “the gestalt is closed.”
Tonic aspects of arousal are also related to cognitive processes. Since the early work of Yerkes and Dodson (1908), there has been replicated evidence that a medium level of arousal is optimal for cognitive performance. It has to be mentioned that the delay period for recall plays an important role when judging the relation of arousal and memory (Revelle & Loftus 1992). High arousal seems to impede short-term recall and to foster longer-term recall, which is an important finding for advertisement and market research. Newer data also suggest that there is a similar “excitation transfer effect” concerning arousal and memory as for arousal and emotions, showing that memory-enhancing effects are semantically independent of the arousal source (Nielson et al. 2005). Such findings are most relevant for the future design of mediated learning environments and the conceptualization of edutainment software or game-based learning applications.
Arousal And Personality
Observations of our social environment as well as the variety of TV programs and movie genres indicate that people differ in their preferences for certain media and media content. Some people prefer horror movies; others like comedies or dramas. An important reason for these individual media preferences is personality differences. Two prominent personality constructs formulated on a psychophysiological basis and closely related to the arousal concept are extraversion and introversion, as introduced by Eysenck and Zuckerman’s concept of sensation seeking.
Extraverts are hypothesized to have a lower habitual arousal level than introverts and thus require stronger external stimulation to achieve or maintain a comfortable activation status. However, the empirical findings to support the psychophysiological basis for the concept are at least controversial and not abundant at all (e.g., Matthews & Gilliand 1999). The concept of sensation seeking is germane to the concept of extraversion, although it has a stronger emphasis on stimulus choice than on social aspects. High sensation seekers generally have a lower level of internal arousal and do therefore need novel, complex, varying, and intense stimuli to maintain a comfortable arousal state. They have been shown to exhibit a stronger orienting response toward novel stimuli. Although the empirical studies with regard to psychophysiological correlates of sensation seeking are also controversial, Zuckerman (2006) could summarize an impressive amount of studies using psychophysiological measures, which support the assumed biological foundation of the concept. With respect to media choice, high sensation seekers have been reported to show a higher preference for sexually explicit material, action adventures, and violent action films, and have also been observed to switch channels more often than low sensation seekers (Zuckerman 2006).
It has to be mentioned that the interrelations between arousal measures and psychological constructs are in most cases complex, and interpretations are rarely straightforward. As different sources of arousal may produce similar outputs in a single measurement, the features of the stimulus material have to be regarded thoroughly at the time the reaction occurs (Ravaja 2004). In addition, most authors stress the importance of monitoring more than one physiological end point, as single physiological measures can indicate a different psychological process. The selection of appropriate arousal measures (i.e., a particular psychophysiological end point) very much depends on the research question (i.e., what kind of arousal has to be measured), but also on economic considerations, its invasiveness (i.e., less invasive measurement techniques are generally preferable), and its validity (i.e., whether the measurement technique is a widely accepted indicator for the variable targeted).
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