Psychophysiology (from Greek ψῡχή, psȳkhē, "breath, life, soul"; φύσις, physis, "nature, origin"; and -λογία, -logia) is the branch of psychology that is concerned with the physiological bases of psychological processes. While psychophysiology was a general, broad field of research in the 1960s and 1970s, it has now become quite specialized, based on methods, topic of studies, and scientific traditions. Methods vary as combinations of electrophysiological methods (such as EEG), neuroimaging (MRI, PET), and neurochemistry. Topics have branched into subspecializations such as social, sport, cognitive, cardiovascular, clinical, and other branches of psychophysiology.
Background
Some people have difficulty distinguishing a psychophysiologist from a physiological psychologist, which has two very different perspectives. Psychologists are interested in why we may fear spiders and physiologists may be interested in the input/output system of the amygdala. A psychophysiologist will attempt to link the two. Psychophysiologists generally study the psychological/physiological link in intact human subjects. While early psychophysiologists almost always examined the impact of psychological states on physiological system responses, since the 1970s, psychophysiologists have also frequently studied the impact of physiological states and systems on psychological states and processes. It is this perspective of studying the interface of mind and body that makes psychophysiologists most distinct. Historically, most psychophysiologists tended to examine the physiological responses and organ systems innervated by the autonomic nervous system. More recently, psychophysiologists have been equally, or potentially more, interested in the central nervous system, exploring brain potentials such as the many types of event-related potentials (ERPs), brain waves, and utilizing advanced technology such as functional magnetic resonance imaging (fMRI), MRI, PET, MEG, and other neuroimagery techniques. A psychophysiologist may look at how exposure to a stressful situation will produce a result in the cardiovascular system such as a change in heart rate (HR), vasodilation/vasoconstriction, myocardial contractility, or stroke volume. Overlaps in areas of interest between psychophysiologists and physiological psychologist may consist of observing how one cardiovascular event may influence another cardiovascular or endocrine event; or how activation of one neural brain structure exerts excitatory activity in another neural structure which then induces an inhibitory effect in some other system. Often, physiological psychologists examine the effects that they study in infrahuman subjects using surgical or invasive techniques and processes. Psychophysiology is closely related to the field of neuroscience, which primarily concerns itself with relationships between psychological events and brain processes. Psychophysiology is also related to the medical disciplines, such as endocrinology, psychosomatic, and psychopharmacology. While psychophysiology was a discipline off the mainstream of psychological and medical science prior to roughly the 1940s, more recently, psychophysiology has found itself positioned at the intersection of psychological and medical science, and its popularity and importance have expanded commensurately with the realization of the inter-relatedness of mind and body.
Measures Psychophysiology measures exist in multiple domains; reports, electrophysiological studies, studies in neurochemistry, neuroimaging, and behavioral methods. Evaluative reports involve participant introspection and self-ratings of internal psychological states or physiological sensations, such as self-report of arousal levels on the self-assessment manikin, or measures of interoceptive visceral awareness such as heartbeat detection. Merits to self-report are an emphasis on accurately understand the participants' subjective experience and understanding their perception; however, its pitfalls include the possibility of participants misunderstanding a scale or incorrectly recalling events. Physiological responses also can be measured via instruments that read bodily events such as heart rate change, electrodermal activity (EDA), muscle tension, and cardiac output. Many indices are part of modern psychophysiology, including brain waves (electroencephalography, EEG), fMRI (functional magnetic resonance imaging), electrodermal activity (a standardized term encompassing skin conductance response, SCR, and galvanic skin response, GSR), cardiovascular measures (heart rate, HR; beats per minute, BPM; heart rate variability, HRV; vasomotor activity), muscle activity (electromyography, EMG), electrogastrogram (EGG), changes in pupil diameter with thought, emotion, and perception (pupillometry), eye movements, recorded via the electro-oculogram (EOG) and direction-of-gaze methods, cardiodynamics, recorded via impedance cardiography, and grip force. These measures are beneficial because they provide accurate and observer-independent objective data recorded by machinery. The downsides, however, are that any physical activity or motion can alter responses, and basal levels of arousal and responsiveness can differ among individuals and even between situations. Neurochemical methods are used to study functionality and processes associated to neurotransmitters and neuropeptides Finally, one can measure overt action or behavior, which involves the observation and recording actual actions, such as running, freezing, eye movement, and facial expression. These are good response measures and easy to record in animals, but they are not as frequently used in human studies.
Uses Psychophysiological measures are often used to study emotion and attention responses to stimuli, during exertion, and increasingly, to better understand cognitive processes. Physiological sensors have been used to detect emotions in schools and intelligent tutoring systems.
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