Psychophysiology is concerned with the physiological bases of psychological processes. For example, where psychologists are interested in why we like a certain TV program, physiologists are interested in the input–output of the cardiovascular system. A psychophysiologist attempts to link the two approaches. The study of the interface of mind and body is what makes psychophysiology most distinct.
Physiological processes here designate physical and/or chemical reactions or accompanying symptoms of human behavior, such as (changes in) cardiovascular activity (e.g., heart rate, blood pressure, peripherial blood volume), electrodermal activity (EDA, like skin conductance), neuroelectric activity (electroencephalography [EEG], such as alpha waves), muscle activity (electromyography [EMG]), body temperature, breathing, eye movements (electrooculography [EOG]), pupillary reflexes, reflexes (such as the blink of an eye), and many more similar processes.
Psychological reactions designate aspects of human behavior that can be expressed in the language of psychology. Here, the focus is primarily on the description, explanation, and prognosis of information processing (cognitive aspect), experience (affective aspect), and behavior dispositions (conative aspect) of individuals. The physiological reactions indicating reaching or leaving a psychological state are therefore described as psychophysiological indicators. Psychophysiological research identifies or manipulates behavioral, cognitive, or emotional states of subjects as the independent variable (for example, through instructions, picture or movie presentations, sensory irritations, etc.) and observes events on the physiological level as the dependent variable. Psychophysiological measurements must therefore be added to the method of observation in most cases.
The Nature Of Psychophysiological Measurement
In contrast to data collection techniques such as interviews, surveys, or observation, psychophysiological data collection is considered more direct, immediate, and objective.
While other measuring procedures that accompany the reception – such as real-time response measurement – can influence the reception experience and information processing itself, psychophysiological processes are considered to be less reactive; they do not require the memory and/or the verbal abilities of the subjects. Hence, they do not interfere with message processing. At the same time, the reactions are scarcely controllable by the observed person. Psychophysiological measurement should therefore enable researchers to gain empirical access to the processing, experiencing, and responding of people that they cannot or will not voice or that is not accessible by other methods.
Emotional experience, for example, is for many people not easy to describe, and is frequently something we are not even conscious of. In addition, emotions are very volatile reactions, that later (for example, in a post hoc interview) are no longer remembered or cannot be described, or are remembered or described incorrectly or altered. Furthermore, the expression of attitudes toward people, advertising, topics, or other matters of opinion are frequently subject to the problem of social desirability or the distorting effects of impression management. Psychophysiological measurement helps to address these problems. These kind of measuring processes finally produce very scattered time-series data that allow the reproduction of the process of media reception and not only its consolidated result. In addition, they provide an excellent database for powerful timeseries analysis.
Questions Of Validity
The main problem of psychophysiology, however, is how far physiological reactions can serve as valid indicators for the psychological concepts in question. Emotions should serve as a good example here because they represent an integrative concept of cognitive, affective, and motivational perspective on human behavior. For example, strong emotional reactions, such as anger or enthusiasm, routinely correspond with increased physiological arousal, which can be measured by changes of electrodermal activity. The valence of the reaction, however, cannot be read from the intensity of the activation, that is whether it designates a positive (happiness) or a negative (anger) emotion. Both emotions are connected with high activation.
Whether a stimulus is evaluated as pleasant or unpleasant depends on the cognitive evaluation or appraisal of that stimulus. Therefore, one psychophysiological parameter alone is seldom a sufficient indicator for a complex psychological phenomenon. Newer findings of psychophysiology stipulate that emotion-specific reactions be indicated by the combined collection and evaluation of several physiological parameters. For example, against the background of circumplex models of emotions, the simultaneous recording of arousal and valence can serve as a clue for experienced emotions. While arousal is measured by means of electrodermal activity, valence can be collected via real-time response (RTR) systems, electromyography, or facial expressions.
The insufficient external validity of psychophysiological examination is often considered a problem. Since the test subjects are closely monitored using numerous sensors and cables, the context is a highly artificial one and not comparable to normal media environments. In the mean time it has been shown that people adapt quickly to the artificial situation and to most sensors in laboratory surroundings. The use of television and the Internet, especially, can be simulated comparably realistically in modern laboratories. Technical development has also contributed to the measuring instruments becoming smaller, more precise, more portable, and more robust. The measurement process therefore has become less intrusive, distracting, and irritating for test subjects.
In psychophysiology physiological phenomena are arranged, summarized, and interpreted in the context of psychological questions, and the complex empirical results integrated with our understanding of anatomy and physiology using a series of concepts. Activation concepts, habituation models, stress reactions, and emotion theories are of especial significance in communication research. In communication studies psychophysiological concepts can be applied to attention and information processing, learning, emotional experience, (sexual) excitement, attitude (change) and persuasion, adaptation research, social cognition, and sleep research.
For example, within the scope of the limited capacity paradigm it can be shown that an average activation level supports information processing optimally and therefore results in the best learning performances. Activation concepts in communication are referred to in mood management theory and excitation transfer theory. Psychophysiological indicators such as excitement here serve as indicators or causes of media selection and effects of media reception. People therefore generally appear to strive for an average excitation level. In these contexts electrodermal activity is a very reliable measure of activation or arousal. It is widely used as an indicator for psychological concepts like attention, task significance, or affective intensity of stimuli experienced by the subjects. Studies have shown that EDA is also highly correlated with self-reported emotional arousal.
Beyond activation, there are several more physiological indicators for different kinds of psychological processes. Orientation reactions are reactions that prepare an organism for reaction to a new stimulus. These orienting responses correspond with a reduction of heart rate, an increase in skin conductance, an increase in muscle tension, pupil dilation, constriction of peripheral blood vessels, expansion of the blood vessels in the brain, as well as alpha blockage (short blockage of the alpha brain waves). However, when a stimulus becomes too intensive, a defense response is triggered, which represents a complementary reaction to the orienting response and is supposed to protect the organism from excessive stimulation.
The pattern of psychophysiological reaction also complements the orienting reaction. It is linked to cognitive avoidance reactions. The so-called fear response appears at sudden appearances of stimuli and is displayed physiologically by an increased blinking reflex, an increase in the heart rate, an expansion of the brain blood cells, and an increase in skin conductance. A similar theoretical systematization differentiates between physiological systems of response activation (behavioral activation system), behavioral inhibition (behavioral inhibition system), and emergency reaction (fight/flight system). Behavioural activation is caused by fulfilled expections and positive feelings; behavioral inhibitions are caused and accompanied by dissonance experiences, which also evoke information collecting processes. Selective attention or the blocking of nonrelevant stimuli is accompanied by an increase in heartbeat frequency and higher heartbeat variation. Active stimuli absorption, however, can be accompanied by a decrease in heartbeat frequency. Coordination performances involve frequent changes between heartbeat acceleration and delay. These concepts and measuring processes are applied primarily in media information processing in reception research (selection, exposure, retention), and adaptation research in media use and media education.
Within the scope of the research on social cognition, attitudes, or persuasion it can be shown that electrical activations of certain facial muscles (facial EMG, especially movements of the corrugator supercilii [brow] muscles and zygomaticus major [cheek] muscles) co-vary with evaluations of actors shown on television. These individual vegetative accompanying reactions are instinctively perceived as emotion of a certain color by observers and again form the foundation for the evaluation of the persons shown (compare facial feedback theory of emotions). Facial EMG can therefore identify subtle reactions to emotional media that are not perceptible using the facial expression coding methodology (e.g., the facial action coding system (FACS) developed by Paul Ekman and Wallace Friesen (Ekman et al. 2001).
Furthermore, the magnitude of the blinking reflex – which can also be measured via facial EMG – varies linearly with affective valence: blinking is more pronounced in response to unpleasant stimuli, compared to pleasant stimuli. In addition, the activity of the oricularis oculi muscle is elevated for arousing versus neutral sounds. It must be noted that facial EMG is not able to discriminate between very subtle differences in emotional valence that are often present in media messages. Compared to self-report, however, facial EMG measures discriminate more effectively between emotional responses, e.g., in television advertising. Furthermore, there are indicators within the context of the psychology of emotion that clear and distinct cardiovascular reactions can be shown for discrete emotions, such as anger, fear, and sadness.
There are currently very promising developments in the field of brain imaging techniques, including positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). These (very expensive and complex) measures use the diversity of the signal intensity in brain tissue in psychophysiological communication research. Through fMRI, it is possible to make visible metabolic processes that accompany brain activities. Since the activity of certain brain regions corresponds with certain psychological correlatives (such as emotions), emotions experienced by a test subject when observing medial stimuli can be identified. There are pilot studies especially in the area of advertising, violence research, video game studies, etc.
In general, perhaps the most important aspect of the psychophysiological approach to psychological phenomena is the attempt to understand the physiological mechanisms that mediate between cognitive and emotional events. There are currently four main trends in psychophysiological communication research: (1) Measuring processes are becoming more precise and can increasingly be used in mobile settings. (2) Various psychophysiological parameters can be measured simultaneously and submitted to pattern recognition. In addition to the increased accuracy of measurements, advanced statistical analysis of recorded data is becoming more and more important. (3) The significance of the analysis of media content processing allows for data to be collected over time which leads to more accurate study of time processes. (4) Continuing use of the three systems approach to brain behavioral relations, i.e., the integration of physiological data with verbal reports and overt behavior study.
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