As a movie audience watches a frightening film, hearts race, palms sweat, pupils dilate, and neck and shoulder muscles brace. Yet, no one has been grabbed by the throat. Psychological activity affects the body. Conversely, physiological changes affect psychological activity. Graphic © G-Stock Studio/ Shutterstock.com.




This powerful idea is Green and Green's psychophysiological principle.




Listen to a mini-lecture on Psychophysiology
© BioSource Software LLC.

Psychophysiology studies the interrelationship between psychological and physiological processes. Andreassi (2007) wrote: "Psychophysiology is the study of relations between psychological manipulations and resulting physiological responses, measured in the living organisms, to promote understanding of the relation between mental and bodily processes." (p. 2) The interrelationship between psychological and physiological processes is dynamic and bidirectional.

interrelationship
Biofeedback practitioners study the basic principles of psychophysiology to understand disease processes and health and how clinical interventions achieve their results.

The idiographic approach, which emphasizes individual differences, is critical to biofeedback practice. Each client's response to stressors is unique, specific, and often complex.

To effectively treat your client, you need to discover your client's characteristic responses to stressors during a psychophysiological profile administered during the assessment stage of treatment. For example, if hand temperature falls and respiration rate increases during math and visual imagery stressors, you might consider training your client to maintain hand temperature around 90o F (32.2o C) while breathing under 7 breaths-per-minute. This approach may be superior to using a standard treatment protocol that disregards your client's unique response pattern or response stereotypy. Graphic © Chris Schmidt/ iStockphoto.com.


 


This unit will challenge the simplistic belief that the sympathetic division fight-or-flight response is our only means of responding to stressors. The parasympathetic branch expands our response options through immobilization, feigning death, passive avoidance, and shutdown, or social engagement supported by the release of the hormone oxytocin. Graphic © Piotr Marcinski/Shutterstock.com.



BCIA Blueprint Coverage


This unit complements the BCIA HRV Biofeedback Blueprint.




This unit covers the Psychophysiological Principle, Homeostasis, Autonomic Balance, Psychophysiological Measurements, Orienting and Defensive Responses, Activation and Habituation, situational Specificity, Law of Initial Values (LIV), Generalization of Biofeedback Training, and the Placebo Effect.

Please click on the podcast icon below to hear a full-length lecture.



Psychophysiological Principle


Green, Green, and Walters' (1970) psychophysiological principle was revolutionary because it proposed a bidirectional relationship between physiological and psychological functioning:
Every change in the physiological state is accompanied by an appropriate change in the mental emotional state, conscious or unconscious, and conversely, every change in the mental emotional state, conscious or unconscious, is accompanied by an appropriate change in the physiological state.
An example of the psychophysiological principle is that facial muscle contraction can influence emotion, and emotion can influence facial muscle contraction. Botox injections, which paralyze facial muscles to treat wrinkles, reduce the intensity of a person's emotional experiences. Elmer Green is pictured below.


Elmer Green in India

Homeostasis


Homeostasis maintains the body’s internal environment within healthy physiological limits. Claude Bernard introduced the basic concept of homeostasis and stated, "The stability of the internal environment is the condition of a healthy life." Cannon (1939) introduced the term homeostasis in 1932 and elaborated on this concept in The Wisdom of the Body.




Listen to a mini-lecture on Homeostasis and Allostasis
© BioSource Software LLC.

The body achieves homeostasis for specific variables, like blood pressure, through interlocking negative and positive feedback systems. Check out the Bozeman Science YouTube video Positive and Negative Feedback Loops.

Two important modifications to the principle of homeostasis are the boundary model and allostasis.

The boundary model challenges the maintenance of set points as rigid and proposes that physiological processes are maintained within acceptable ranges.

Allostasis means the maintenance of stability through change and is a process that complements homeostasis. Allostasis is achieved by anticipating challenges and adapting through behavior (including learning) and physiological change. Therapists utilize allostasis when they teach patients to use an abbreviated relaxation exercise (low-and-slow breathing) when they anticipate stressors (traffic jams).

McEwen and Seeman's (1999) allostatic load model proposes that acute and repeated stressors can produce harmful physiological changes. Graphic © GalinaPhoto/iStockphoto.com.



Autonomic Balance


Wenger (1972) called the ratio of sympathetic to parasympathetic activation autonomic balance. He proposed that resting individuals are located along a continuum ranging from SNS to PNS dominance.

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Normally distributed A-bar scores, which measure location on this continuum, are calculated from a battery of autonomic measurements. Low A-bar scores indicate SNS dominance, while high A-bar scores suggest PNS dominance. Most subjects show intermediate scores. Wenger and colleagues reported that individuals with low A-bar scores, whom he called sympathicotonics, suffered an elevated incidence of neurotic, psychotic, psychosomatic, and medical disorders.

Generally, low and high A-bar scores seem to predispose individuals to develop psychological and medical disorders. Where SNS dominance (low A-bar scores) may result in cardiac arrhythmia and essential hypertension, PNS dominance (high A-bar scores) may be associated with asthma, colitis, and hypotension. Graphic © alexsl/iStockphoto.com.


The healthiest pattern of autonomic balance involves intermediate A-bar scores where neither the SNS nor the PNS overwhelms the other.

Psychophysiological Measurements


Psychophysiologists monitor tonic, phasic, and spontaneous psychophysiological activity.




Listen to a mini-lecture on Tonic and Phasic Activity © BioSource Software LLC.

Tonic activity measures background activity and is the magnitude of physiological activity over a specified period before stimulating the subject. A resting baseline, where a participant sits quietly without breathing or relaxation instructions, or feedback for 3 or 5 minutes, measures tonic activity. Clinicians obtain pre- and post-baselines to measure the psychophysiological change in variables like heart rate variability or hand temperature within and across training sessions.

Phasic activity is a discrete response evoked by a specific stimulus, like being surprised. Since subjects continuously react to environmental and internal stimuli that we cannot directly observe, interpreting phasic activity can be challenging. Graphic © ideabug/iStockphoto.com.






Spontaneous responses
are physiological changes in the absence of detectable stimuli. These changes are important to researchers because they can confound the measurement of phasic activity. For example, suppose a spontaneous increase in skin conductance occurs as a subject is shown an emotionally-charged slide. In that case, a researcher could mistakenly conclude that the slide increased conductance more than it did (Stern, Ray, & Quigley, 2001).

Orienting and Defensive Responses


When exposed to a novel stimulus, an orienting response prepares us to deal with this challenge.

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Pavlov's (1927) orienting response is a "What is it?" reaction to stimuli like the sound of a vase crashing. The orienting response includes (1) increased sensory sensitivity, (2) head (and ear) turning toward the stimulus, (3) increased muscle tone (reduced movement), (4) EEG desynchrony, (5) peripheral constriction and cephalic vasodilation, (6) a rise in skin conductance, (7) heart rate slowing, and (8) slower, deeper breathing. An orienting response rapidly habituates since it is no longer needed once we respond to a novel stimulus.

In contrast, a defensive response is a slowly habituating response pattern that limits harm from intense stimulation. This pattern includes (1) reduced sensory sensitivity, (2) a tendency to move away from the stimulus, (3) heart rate increase, and (4) both peripheral and cephalic vasoconstriction. For example, a loud noise in a workplace environment might elicit a defensive response.

Activation and Habituation


Activation was Duffy’s (1972) term for arousal.

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Activation

This concept originated in Cannon's (1915) idea of the body's integrated preparation to fight or flee a potential threat. Activation implies a unidimensional continuum that ranges from low to high activation. For example, high activation might be associated with elevated blood pressure, heart rate, and respiration rate. Low activation might be associated with reduced responses to these variables.

Duffy (1957) hypothesized that performance rises with increased physiological arousal to an optimal level for a specific task and then declines with further arousal. This relationship is an inverted U-shaped curve. Task complexity and novelty may determine the optimal level of arousal. The optimal level of arousal will be lower for more complex and novel tasks. John Balven created the illustration below.



                           

Problems with Activation Theory

Lacey (1967) and others have strongly criticized activation theory. The main concerns are that arousal is not a single dimension. Individuals show unique response patterns, different stimuli elicit specific response patterns in most people, other emotions are associated with distinct physiological changes, and responses can be complex.

1. Lacey argued that arousal is not a single dimension. He believed that researchers should differentiate between autonomic, behavioral, and cortical arousal since these different forms of arousal are not interchangeable. For example, when heterosexual men observe slides of nude women, heart rate may increase while finger blood flow may not change. If we only use finger blood flow as our index of arousal, we might mistakenly conclude that the male subjects are not aroused (Stern, Ray, & Davis, 1980).

2. Individuals exhibit unique response patterns, called a response stereotypy, in which they show consistent physiological responses when encountering stimuli that share the same intensity and elicit similar emotions. For example, a patient may raise her heart rate and blood pressure when delivering a report during a business meeting or completing an assignment under time pressure.

Individual response stereotypy occurs because our clients possess different diatheses (vulnerabilities) and enter treatment with unique learning histories. During an assessment, a clinician conducts a psychophysiological profile (PSP) to determine a client's response stereotypy by presenting several mild stressors.

3. Specific stimuli elicit a distinctive response pattern in most participants instead of simply altering activation. This is the principle of stimulus-response specificity. For example, individuals may increase their skeletal muscle tone when challenged to compete.

Situational specificity is an example of stimulus-response specificity. It means that a physiological response (blood pressure elevation) does not occur randomly and is most likely in situations with unique characteristics. A situation's properties may include the location (office), time of day (morning), activity (conference), individuals present (employer), and personal emotional state (anxiety).

A client's elevated blood pressure may be classically or operantly conditioned. They may be unaware of learning this response since its symptoms are largely "silent" and both processes involve implicit learning. Due to associative learning, the presence of one or more situational cues may elicit a complete physiological response.

Clinicians investigate the situational specificity of presenting complaints when they conduct a history, perform a psychophysiological profile (PSP), ask the client to maintain a symptom journal, and monitor the client in multiple real-world settings (blood pressure measurement in the office and while stalled in traffic). Situational information is crucial to creating stimulus hierarchies when using systematic desensitization to treat a phobia.

4. Primary emotions are associated with unique physiological changes. This is the concept of emotional response specificity. The six primary facial expressions are surprise, anger, sadness, disgust, fear, and happiness. Research by Ekman and colleagues with facial expressions showed that anger increases heart rate and skin temperature, fear increases heart rate, and decreases skin temperature. Happiness increases heart rate but does not affect skin temperature.

Schwartz, Weinberger, and Singer (1981) studied cardiovascular patterning in six emotions using imagery, nonverbal expression, and exercise tasks. Their dependent variables were diastolic and systolic blood pressure and heart rate. Participants' cardiovascular responses distinguished anger from fear (blood pressure) and anger and fear from happiness and sadness. Ax (1953) reported that 7 of 14 autonomic measures discriminated between fear and anger.

5. Responses to a stimulus can be complex, with some physiological indices increasing and others decreasing. This builds on the principle of stimulus-response specificity. Specific stimuli elicit a distinctive response pattern, which is often complex. Lacey called this intricate pattern directional fractionation. For example, when a Capitol Hill police officer hears a noise, EEG and skin conductance may increase cortical activation while GI tract activity decreases.


Habituation

Habituation is the opposite of arousal. A person gradually ceases to respond or reduces their response to a constant stimulus.

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For example, after 15 trials of listening to a moderate intensity tone, heart rate might no longer increase. Predictable, low-intensity stimuli that convey no new information and require no response readily produce habituation. Habituation is inhibited when a stimulus is intense, complex, and unique, and the subject must respond to it (rate its unpleasantness).

The orienting response and defensive response differ in their speed of habituation. Orienting responses rapidly habituate, while defensive responses habituate very slowly.

Situational Specificity


Situational specificity means that a physiological response (blood pressure elevation) does not occur randomly and is most likely in situations with special characteristics.

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A situation's properties may include the location (office), time of day (morning), activity (conference), individuals present (employer), and personal emotional state (anxiety). A client's hypertensive response may be classically or operantly conditioned, which means they may be unaware of learning this response since its symptoms are largely "silent," and both processes involve implicit learning. Due to associative learning, the presence of one or more situational cues may elicit a complete physiological response.

Clinicians investigate the situational specificity of presenting complaints when they conduct a history, perform a psychophysiological profile (PSP), ask the client to maintain a symptom journal, and monitor the client in multiple real-world settings (blood pressure measurement in the office and while stalled in traffic). Situational information is crucial in creating stimulus hierarchies when using systematic desensitization to treat a phobia.

Law of Initial Values (LIV)


Wilder (1967) argued that the size of our response to a stimulus depends on a physiological variable's starting value.

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Wilder’s law of initial values (LIV) predicts that the higher the initial value of a physiological variable, the less its tendency to change. For example, a subject who normally breathes rapidly should only slightly increase their respiration rate when exposed to a loud sound. Homeostatic mechanisms (negative feedback) are responsible for this phenomenon.

Hord, Johnson, and Lubin (1964) found that the LIV applies to heart and respiration rates but not to skin conductance or skin temperature.

Stern, Ray, and Quigley (2001) reported that studies support the LIV for heart rate and skin resistance but not for skin conductance.




Berntson and colleagues (1994) questioned the LIV's value and encouraged researchers to develop an "autonomic constraints" model tied to underpinning physiology.


Relevance of the LIV for Biofeedback

Researchers studying phasic (rapidly changing) measures may consider employing statistical methods to control the influence of prestimulus values on the size of physiological responses.

The LIV is a principle—not a law—and does not apply to all subjects and response systems. Jamieson (1993) questioned the LIV’s value for psychophysiological research since it can be influenced by several factors (measurement errors, reactivity or response to the measurement process, skew or asymmetrical distribution of scores, and variance or difference among scores).

Researchers can determine whether the LIV is relevant by computing the correlation between prestimulus and poststimulus values. Geenen and van de Vijver (1993) suggested that the LIV may be less common than perceived and correction methods may harm the data more than the phenomenon itself.

Generalization of Biofeedback Training


The key muscle hypothesis and hand-warming specificity have important implications for biofeedback training.

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Key Muscle Hypothesis

The key muscle hypothesis is the proposition that a single muscle indexes activity in other muscle groups. Research strongly contradicts this view: (1) SEMG values across different sites are uncorrelated, (2) single-site SEMG values are not correlated with generalized tension or autonomic arousal, and (3) SEMG reductions at one site (frontalis) do not automatically generalize to other sites.

The key muscle hypothesis is invalid because there is no key upper body or lower body muscle group. The musculoskeletal system functions very specifically--we simultaneously contract and relax adjacent agonist-antagonist muscle pairs at a joint. This belief has resulted in clinicians mistakenly training the frontalis muscle to lower autonomic arousal or relax muscles on the upper trunk.


                                                   

               

Hand-Warming Specificity

The cardiovascular system can function very precisely, just like the musculoskeletal system. Temperature training can produce extremely site-specific changes. For example, vasodilation in the right hand need not generalize to the left hand or the feet. The picture below shows the placement of a thermistor (temperature sensor) on the index finger's dorsal surface.


thermistor
 

Clinicians should never expect hand-warming to generalize beyond the actual site (digit) trained. Depending on training procedure and individual differences, hand-warming might generalize to other digits on the same hand or to the other hand for some clients but not for others.

The temperature map below shows mean undergraduate finger and web dorsum temperatures (Lammy et al., 2004).



The Placebo Effect


Placebos are inert interventions that can produce a significant clinical response. Both the symptoms and therapeutic response are real and measurable in a placebo response.




Listen to a mini-lecture on the Placebo Effect © BioSource Software LLC. Check out Eric Mead's TED Talk The Magic of the Placebo. Graphic © kasezo/Shutterstock.com.





Placebos can be pharmacological (e.g., drug), procedural (e.g., osteopathic manipulation), psychological (e.g., conversation), and environmental (e.g., the clinic setting). Contrary to clinical lore:

(1) The percentage of patients who improve with a placebo can exceed 60%.

(2) Placebo responses can last as long as improvement with prescription drugs.

(3) Placebos are more effective when closely following effective medication (classical conditioning and expectancy).

(4) Effective medication is less effective when it follows ineffective medication (classical conditioning and expectancy).

(5) Open-label placebos, where patients are told they receive placebos, can produce clinical improvement (Schaefer et al., 2018).

An active placebo, which adds an ingredient that produces an unrelated side effect, yields a therapeutic response in about 60% of people. Prescription drugs elicit a therapeutic response in 50% (actual practice) to 70% (supervised drug trial) of the population. Placebos have the most significant effects on symptoms or disorders that wax and wane over time (e.g., major depression and chronic pain). The placebo response to drug treatment of depression increases by about 7% per decade (Advokat, Comaty, & Julien, 2019).

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Placebos seem to trigger a homeostatic response via stimulus-response learning, expectancy, and the release of endogenous neurotransmitters like endorphins and adrenaline-like catecholamines. This may mirror changes (therapeutic effects, time course, and duration of effect) produced by prescription drugs.

Petrovic and colleagues (2002) showed that opioid analgesia and placebo analgesia increased activity in the rostral anterior cingulate cortex and the brainstem.

Wager et al. (2004) used the functional MRI (fMRI) to study the placebo effect. They exposed volunteers to painful shocks or heat. Participants told that an "anti-pain cream" had been applied to their arms reported less pain than those not told about the cream. The fMRI showed that participants in the "anti-pain" cream condition increased activity in the prefrontal cortex and decreased activity in pain-processing regions of the thalamus, somatosensory cortex, and cerebral cortex.

Kaptchuk et al. (2010) reported the results of a randomized controlled study of 80 Irritable Bowel Syndrome (IBS) patients. Fifty-nine percent of those told that they would receive inert pills and that ‘‘placebo pills, something like sugar pills, have been shown in rigorous clinical testing to produce significant mind-body self-healing processes’’ improved. In contrast, only 35% of patients randomly assigned to a no-treatment control group showed gains.

Right parahippocampal gyrus (r-PHG) connectivity measured using fMRI scans predicted placebo-mediated analgesia in patients diagnosed with chronic knee osteoarthritis (Tétreault et al., 2016). Graphic courtesy of Wikimedia Commons.




Inter-Brain Synchrony


Therapy provides a structured environment where patients can repeatedly experience and strengthen inter-brain synchrony (Meehan, 2025; Sened et al., 2022). In inter-brain synchrony, the neural activity of two individuals becomes aligned during social interactions. This synchrony is observed in therapeutic settings when a therapist and a patient engage in shared emotional and cognitive processes, such as maintaining eye contact, mirroring expressions, and synchronizing speech rhythms. This mutual alignment of brain activity, often termed neural coupling, facilitates a deeper interpersonal connection and effective communication Over time, this repeated neural coupling can lead to lasting neurobiological adaptations, reinforcing healthier emotional and cognitive frameworks. Vagus nerve graphic © Axel_Kock/Shutterstock.com.




Further evidence suggests that synchrony strengthens emotional bonds and improves cognitive flexibility. When neural coupling occurs, it facilitates better communication between brain regions associated with decision-making, problem-solving, and emotional processing. This may explain why clients who engage in therapy with high levels of synchrony often experience deeper insights, improved emotional resilience, and greater capacity for behavioral change. Understanding and intentionally fostering this synchrony can, therefore, be a powerful tool in therapeutic practice, enhancing the overall efficacy of interventions.

For therapists, these findings underscore the importance of fostering therapeutic synchrony as an active component of treatment. Beyond verbal communication, nonverbal cues such as body language, tone of voice, and paced responsiveness contribute significantly to inter-brain synchrony. Therapists who practice mindfulness, attunement, and embodied presence may enhance their ability to facilitate neural synchrony with clients, potentially amplifying the effectiveness of therapy.

Moreover, this perspective encourages therapists to view relational healing not only as a psychological process but also as a neurobiological one. Clients who struggle with attachment issues, social difficulties, or trauma may particularly benefit from interventions that emphasize relational presence, attunement, and co-regulation.

Relational presence refers to the therapist’s capacity to fully engage with the client, establishing an environment of genuine connection and trust where the client feels seen and valued. Attunement is the process by which the therapist accurately perceives and sensitively responds to the client’s emotional signals, thereby fostering a therapeutic interaction that validates the client’s internal experience. Co-regulation involves a collaborative dynamic in which the therapist supports the client in managing and modulating their emotional states, ultimately aiding the client in developing effective self-regulation skills. Collectively, these processes help create a secure relational framework essential for healing and developing adaptive emotional responses.

Psychophysiological Assessment


Client assessment is a collaborative process that starts with an orientation to biofeedback, client recording symptoms, a psychophysiological history, referral to physicians to investigate related medical complaints, and a psychophysiological stress profile (Moss & Shaffer, 2022).


Caption: Don Moss

Psychophysiological Stress Profile Overview

A psychophysiological stress profile (PSP) monitors multiple physiological variables under standardized resting, stress, and recovery conditions. Clinicians use a PSP to detect chronic problems that depress or elevate physiological measures, overactivation in response to stressors, and difficulty recovering from stress trials. A PSP provides a comprehensive picture of the client's psychophysiological health and identifies the biofeedback modalities to help clients achieve their training goals.

In a typical PSP, a practitioner will monitor hand temperature (TEMP), heart rate (HR) and heart rate variability (HRV), respiration (RESP), skeletal muscle electrical activity (SEMG), skin conductance (SCL), and possibly brain electrical activity (EEG). The clients' presenting complaints may determine the placement of SEMG and EEG sensors. For example, a clinician may use left and right SEMG channels to record cervical paraspinal muscle activity in tension-type headaches.

PSP Structure

A clinician may divide the PSP into a 5-minute baseline (no feedback or breathing instructions), a 3-minute relaxation period (relaxation instructions), a 3-minute stress trial (e.g., visualizing a recent stressful event), a 3-minute recovery period, a second 3-minute stress trial, and a final 3-minute recovery period.




How the PSP Can Guide Treatment Planning

The PSP provides extensive information about a client's psychophysiology to guide treatment planning. Instead of a manualized "one size fits all" approach, the PSP enables a practitioner to tailor training to a client's unique strengths and needs.

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First, the baseline reveals which values are depressed or elevated. This can help identify systems that are dysregulated in everyday life. Second, the relaxation trial evaluates a client's ability to self-regulate their physiology. Third, the stress trials show which systems over or under react to cognitive and emotional challenges. Fourth, the recovery trials assess a client's ability to restore relaxed physiology following stressors.

When the Psychophysiological History and PSP identify a distinct stereotypy, a practitioner can target the systems that may contribute to a client's systems. For example, a practitioner might recommend muscle relaxation training if a client's upper back and neck muscles were excessively tense during baseline, did not loosen during relaxation, tensed further during both stressors, and did not recover following the stressors.



Glossary


A-bar: Wenger’s shorthand for the ratio of sympathetic to parasympathetic excitation. Patients with low A-bar scores are sympathetic-dominant, and those with high A-bar scores are parasympathetic dominant.

accentuated antagonism:
the parasympathetic nervous system's ability to directly oppose sympathetic action, such as slowing the heart by 20 or 30 beats.

activation: Duffy’s term for arousal originated with Cannon’s fight-or-flight response.

active placebo: a placebo combined with an additive to produce a side effect that can elicit a therapeutic response rate in about 60% of patients.

allostasis: the maintenance of stability through change by mechanisms that anticipate challenges and adapt through behavioral and physiological change.

allostatic load model: McEwen and Seeman’s hypothesis that biological responses to stress can harm the body when stressors are acute or repeatedly occur.

attunement: the process by which a therapist accurately perceives and responds to a clients emotional state.

autonomic balance: Wenger’s concept of a ratio of sympathetic to parasympathetic excitation.

autonomic nervous system: the subdivision of the peripheral nervous system that includes enteric, parasympathetic, and sympathetic.

boundary model: the position that setpoints are not rigid and that physiological processes are maintained within acceptable ranges.

central nervous system: the division of the nervous system that includes the brain, spinal cord, and retina.

co-regulation: the process through which one person helps another regulate their emotional state through interaction and connection.

defensive response: a very slowly habituating response pattern that limits harm from intense stimulation. This pattern includes (1) reduced sensory sensitivity, (2) a tendency to move away from the stimulus, (3) heart rate increase, and (4) both peripheral and cephalic vasoconstriction.

diathesis: vulnerability. For example, a genetic predisposition to gain weight.

directional fractionation: Lacey’s concept of a complex pattern of physiological response to a stimulus where some indices increase and others decrease.

emotional response specificity: the hypothesis that primary emotions are associated with unique physiological changes.

enteric division: a subdivision of the autonomic nervous system that regulates the gut and is innervated by sympathetic and parasympathetic branches.

epinephrine: an adrenal medullary hormone that increases muscle blood flow, converts stored nutrients into glucose for use by skeletal muscles, and initiates cardiac muscle contraction when it binds to ß1 receptors.

freeze response: immobilization when facing a threat you cannot fight or flee.

functional MRI (fMRI): magnetic resonance imaging procedure that can detect small changes in brain metabolism.

habituation: the weakening or disappearance of a response to a constant stimulus.

heart rate variability (HRV): the organized fluctuation of time intervals between successive heartbeats defined as interbeat intervals.

homeostasis: the state of dynamic constancy achieved by stabilizing conditions about a setpoint, whose value may change over time.

homeostat: device that maintains homeostasis. For example, the hypothalamus.

hypothalamus: the forebrain structure below the thalamus that dynamically maintains homeostasis controlling the autonomic nervous system, endocrine system, survival behaviors, and interconnections with the immune system.

idiographic approach: a research strategy that emphasizes individual differences.

inter-brain plasticity: the capacity of the brain to adapt and change based on repeated neural synchrony with another person.

key muscle hypothesis: the discredited proposition that a single muscle indexes activity in other muscle groups.

law of initial values: Wilder’s proposition that the size of our response to a stimulus depends on a physiological variable's starting value. This principle has only been demonstrated for heart rate, respiration rate, and skin resistance.

mass activation: the simultaneous stimulation of adjacent ganglia (cell bodies) in the sympathetic chain during emergencies allows the sympathetic nervous system to produce many coordinated changes at once. For example, increased heart rate, respiration rate, and sweat gland activity.

medulla: a brainstem structure that regulates blood pressure, defecation, heart rate, respiration, vomiting, the autonomic nervous system, and distributes signals between the brain and spinal cord.

neural coupling: the synchronization of brain activity between two individuals during social or therapeutic interactions.

norepinephrine: an adrenal medullary hormone that increases muscle blood flow and converts stored nutrients into glucose for skeletal muscles.

open-label placebo: an inert treatment disclosed as a placebo to patients.

orienting response: Pavlov’s "What is it?" reaction to stimuli like the sound of a vase crashing that includes (1) increased sensory sensitivity, (2) head (and ear) turning toward the stimulus, (3) increased muscle tone (reduced movement), (4) EEG desynchrony, (5) peripheral constriction and cephalic vasodilation, (6) a rise in skin conductance, (7) heart rate slowing, and (8) slower, deeper breathing.

parasympathetic division: the autonomic nervous system subdivision that regulates activities that increase the body’s energy reserves, including salivation, gastric (stomach) and intestinal motility, gastric juice secretion, and increased blood flow to the gastrointestinal system.

parasympathetic dominance: Wenger’s concept of greater parasympathetic activation than sympathetic activation.

peripheral nervous system: nervous system subdivision that includes autonomic and somatic branches.

phasic: a brief change in physiological activity in response to a discrete stimulus. For example, a single skin potential response in reaction to a sudden tone.

placebo: an inert intervention that can produce a therapeutic response rate in about 30% of patients.

polyvagal theory: the theory that the unmyelinated vagus (dorsal vagus complex) and newer myelinated vagus (ventral vagal complex) mediate competing adaptive responses.

psychophysiological principle: Green, Green, and Walter’s concept that there is a bidirectional relationship between physiological and psychological functioning. For example, facial muscle contraction can influence emotion, and emotion can influence facial muscle contraction.

Psychophysiological Stress Profile (PSP): structured assessment procedure that monitors multiple physiological variables under standardized resting, stress, and recovery conditions.

relational presence: a therapist's ability to be fully engaged and attuned to a client in a way that fosters connection and trust.

response stereotypy: a consistent pattern of physiological responses when an individual encounters stimuli with the same intensity and elicit similar emotions. For example, a patient may raise her heart rate and blood pressure when delivering a report during a business meeting or completing an assignment under time pressure.

resting baseline: a tonic measure of psychophysiological activity (e.g., temperature) without breathing or relaxation instructions and feedback.

situational specificity: the occurrence of a physiological response in specific situations. For example, blood pressure increase during a dental examination.

somatic nervous system: the peripheral nervous system subdivision that receives external sensory and somatosensory information and controls skeletal muscle contraction.

spontaneous responses: physiological changes in the absence of detectable stimuli. For example, skin conductance responses when no tones are presented to a subject.

stimulus-response specificity: specific stimuli elicit a distinctive response pattern in most individuals instead of simply altering activation. For example, subjects may increase their skeletal muscle tone when challenged to compete.

sympathetic dominance: Wenger’s concept of greater sympathetic activation than parasympathetic activation.

sympathetic nervous system: the autonomic nervous system branch that regulates activities that expend stored energy, such as when we are excited.

sympathicotonics: Wenger’s term for sympathetic-dominant individuals who they hypothesized to suffer an elevated incidence of neurotic, psychotic, psychosomatic, and medical disorders.

therapeutic synchrony: the alignment of emotional and cognitive processes between therapist and client that enhances the therapeutic process.

tonic: a background level of physiological activity. For example, a 5-minute average of hand temperature.

vagal withdrawal: the inhibition of the myelinated vagus, often by daily stressors.

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Essential Skills


1. Interview a client about the history and prior treatment of the presenting complaints, the individual’s life situation, including stressors and resources, and her understanding of the cause(s) and consequences of these symptoms.

2. Explain the purpose and procedures of a psychophysiological profile to a client.

3. Administer a psychophysiological profile to a client utilizing several modalities and containing pre-baseline, stressor, recovery, and relaxation conditions. Explain your selection of the modalities and placements used.

4. Demonstrate how to detect and remove artifacts from the raw signals that were monitored.

5. Evaluate and summarize the findings of the psychophysiological profile, relate them to the client’s presenting complaints, and identify training goals based on these data.

6. Explain the results from the psychophysiological profile and training goals to your client.

7. Develop a treatment plan for your client based on the interview and psychophysiological profile.

8. Explain the treatment plan to your client.

Assignment


Now that you have completed this unit, how might it change how you explain psychophysiological concepts like the autonomic nervous system to your clients?

References


Advokat, C. D., Comaty, J. E., & Julien, R. M. (2019). Julien's primer of drug action (14th ed.). Worth Publishers.

Andreassi, J. L. (2007). Psychophysiology: Human behavior and physiological response (5th ed.). Lawrence Erlbaum Associates, Publishers.

Begley, S. (2005). How mirror neurons help us empathize, really feel others' pain. The Wall Street Journal, B1.

Berntson, G. G., Cacioppo, J. T., & Quigley, K. S. (1993). Cardiac psychophysiology and autonomic space in humans: Empirical perspectives and conceptual implications. Psychological Bulletin, 114, 296-322. https://doi.org/10.1037/0033-2909.114.2.296

Berntson, G. G., Urchino, B. N., & Cacioppo, J. T. (1994). Origins of baseline variance and the Law of Initial Values. Psychophysiology, 31(2), 204-210. https://doi.org/10.1111/j.1469-8986.1994.tb01042.x

Brannon, L., Updegraff, J. A., & Feist, J. (2022). Health psychology: An introduction to behavior and health (10th ed.). Wadsworth.

Breedlove, S. M., & Watson, N. V. (2020). Behavioral neuroscience (9th ed.). Sinauer Associates, Inc.

Cacioppo, J. T., Tassinary, L. G., & Berntson, G. G. (Eds.). (2007). Handbook of psychophysiology (3rd) ed.). Cambridge University Press.

Coull, J. A., Beggs, S., Boudreau, D., Boivin, D., Tsuda, M., Inoue, K., Gravel, C., Salter, M. W., & De Konink, Y. (2005). BDNF from microglia causes the shift in neuronal anion gradient underlying neuropathic pain. Nature, 438, 1017-1021. https://doi.org/10.1038/nature04223

Dahr, A. K., Lambert, G. W., & Barton, D. A. (2016). Depression and cardiovascular disease: Psychopbiological mechanisms. In M. E. Alvarenga, & D. Byrne (Eds.). Handbook of psychocardiology. Springer Singapore.

Fox, S. I., & Rompolski, K. (2022). Human physiology (16th ed.). McGraw-Hill.

Gevirtz, R. (2013). The nerve of that disease: The vagus nerve and cardiac rehabilitation. Biofeedback, 41, 32-38. https://doi.org/10.5298/1081-5937-41.1.01

Green, E., Green, A. M., & Walters, E. D. (1970). Voluntary control of internal states: Psychological and physiological. Journal of Transpersonal Psychology, 2, 1-26.

Gurung, R. A. R. (2018). Health psychology: Well-being in a diverse world (4th ed.). Thompson Wadsworth.

Hugdahl, K. (1995). Psychophysiology: The mind-body perspective. Harvard University Press.

Kaptchuk, T. J., Friedlander, E., Kelley, J. M., Sanchez, M. N., Kokkotou, E., Singer, J. P., Kowalczykowski, M., Miller, F. G., Kirsch, I., & Lembo, A. J. (2010). Placebos without deception: A randomized controlled trial in Irritable Bowel Syndrome. PLoS ONE 5(12), e15591. https://doi.org/10.1371/journal.pone.0015591.

Khazan, I. Z. (2013). The clinical handbook of biofeedback: A step-by-step guide for training and practice with mindfulness. John Wiley & Sons, Ltd.

Khazan (2019). A guide to normal values for biofeedback. In D. Moss & F. Shaffer (Eds.). Physiological recording technology and applications in biofeedback and neurofeedback (pp. 2-6). Association for Applied Psychophysiology and Biofeedback.

Kingsley, R. E. (2000). Concise textbook of neuroscience (2nd ed.). Lippincott Williams & Wilkins.

LeDoux, J. (2002). Synaptic self. Viking Penguin.

Malta, L. S., Blanchard, E. B., Freidenberg, B. M., Galovski, T. E., Karl, A., & Holzapfel, S. R. (2001). Psychophysiological reactivity of aggressive drivers: An exploratory study. Applied Psychophysiology and Biofeedback, 26(2), 95-116.

Meehan, Z. M. (2025). 5-min science: Inter-brain plasticity can enhance psychotherapy. https://www.biosourcesoftware.com/post/5-min-science-inter-brain-plasticity-can-enhance-psychotherapy

Moss, D., & Shaffer, F. (2022). A primer of biofeedback. Association for Applied Psychophysiology and Biofeedback.

Nunan, D., Sandercock, G. R. H., & Brodie, D. A. (2010). A quantitative systematic review of normal values for short-term heart rate variability in healthy adults. Pacing and Clinical Electrophysiology, 33(11), 1407-1417. https://doi.org/10.1111/j.1540-8159.2010.02841.x

Olshansky, B., Sabbah, H. N., Hauptman, P. J., & Colucci, W. S. (2008). Parasympathetic nervous system and heart failure: Pathophysiology and potential implications for therapy. Circulation, 118, 863-871. https://doi.org/10.1161/CIRCULATIONAHA.107.760405

Pennebaker, J. W., Kiecolt-Glaser, J. K., & Glaser, R. (1988). Disclosure of traumas and immune function: Health implications for psychotherapy. Journal of Consulting and Clinical Psychology, 56, 239-245. https://doi.org/10.1037//0022-006x.56.2.239

Petrovic, P., Kalso, E., Petersson, K. M., & Ingvar, M. (2002). Placebo and opioid analgesia--Imaging a shared neuronal network. Science, 295, 1737-1740. https://doi.org/10.1126/science.1067176

Pinel, P. J., & Barnes, S. (2017). Biopsychology (10th ed.). Pearson Education, Inc.

Poole, L., Dickens, C., & Steptoe, A. (2011). The puzzle of depression and acute coronary syndrome: Reviewing the role of acute inflammation. Journal of Psychosomatic Research, 71(2), 61-68. https://doi.org/10.1016/j.jpsychores.2010.12.009

Porges, S. W. (2011). The polyvagal theory: Neurophysiological foundations of emotions, attachment, communication, and self-regulation. W. W. W. Norton & Company.

Rao, M., & Gershon, M. D. (2016). The bowel and beyond: The enteric nervous system in neurological disorders. Nature Reviews Gastroenterology & Hepatology, 13, 517–528. https://doi.org/10.1038/nrgastro.2016.107

Rizzollati, G., & Sinigaglia, C. (2006). Mirrors in the brain. Oxford University Press.

Schwartz, G. E., Weinberger, D. A., & Singer, J. A. (1981). Cardiovascular differentiation of happiness, sadness, anger, and fear following imagery and exercise. Psychosomatic Medicine, 43, 343-364. https://doi.org/10.1097/00006842-198108000-00007

M. S. Schwartz, & F. Andrasik (Eds.). (2003). Biofeedback: A practitioner's guide (3rd ed.). The Guilford Press.

Schwartz, S. (2015). Viva vagus: Wandering nerve could lead to range of therapies. Science News, 188(11), 18.

Schaefer, M., Sahin, T., & Berstecher, B. (2018). Why do open-label placebos work? A randomized controlled trial of an open-label placebo induction with and without extended information about the placebo effect in allergic rhinitis. Plos One, 13,(3), e0192758. https://doi.org/10.1371/journal.pone.0192758. eCollection 2018

Sened, H., Zilcha-Mano, S., & Shamay-Tsoory, S. (2022). Inter-brain plasticity as a biological mechanism of change in psychotherapy: A review and integrative model. Frontiers in Human Neuroscience, 16, 955238. https://doi.org/10.3389/fnhum.2022.955238

Shaffer, F., McCraty, R., & Zerr, C. L. (2014). A healthy heart is not a metronome: An integrative review of the heart’s anatomy and heart rate variability. Frontiers in Psychology, 5, 01040. https://doi.org/0.3389/fpsyg.2014.01040

Shaffer, F., Meehan, Z. M., & Zerr, C. L. (2020). A critical review of ultra-short-term heart rate variability norms researchFrontiers in Neuroscience, 14, 594880. https://doi.org/10.3389/fnins.2020.594880

Stern, R. M., Ray, W. J., & Quigley, K. S. (2001). Psychophysiological recording (2nd ed.). Oxford University Press.

Tétreault, P., Mansour, A., Vachon-Pressau, E., Schnitzer, T. J., Apkarian, A. V., & Baliki, M. N. (2016). Brain connectivity predicts placebo response across chronic pain trials. PLoS Biology, 14(10), e1002570. https://dx.doi.org/10.1371/journal.pbio.1002570

Thompson, M. (2005). Intentions, empathy, and theory of mind: Implications for personality and psychotherapy. Presentation to the Annual Meeting of the American Association for the Advancement of Science (AAAS).

Tortora, G. J., & Derrickson, B. H. (2021). Principles of anatomy and physiology (16th ed.). John Wiley & Sons, Inc.

Tracey, K. J. (2007). Physiology and immunology of the cholinergic anti-inflammatory pathway. Journal of Clinical Investigation, 117(2), 289-296. PMID: 17273548

White, C., & Lammy, D. (2004). Infrared hand temperature mapping [Abstract]. Applied Psychophysiology and Biofeedback, 29(4), 306.

Wickramasekera, I. A. (1988). Clinical behavioral medicine: Some concepts and procedures. Plenum Press.

Wilson, J. (2003). Biological foundations of human behavior. Wadsworth/Thompson Learning.