The experience of emotion is associated with a variety of bodily changes, both overt and covert. Overt bodily manifestations of emotions are obvious and observable. But the covert organic changes are detected only by special procedures, and modern recording devices including computers. Following overt and covert changes occur in the body at the time of emotion:

  • Face becomes red with excitement or anger;
  • Eyes are protruded;
  • The pupils of the eyes are dilated.
  • Respiration becomes more rapid;
  • The electrical resistance of the skin decreases;
  • The blood clots more quickly at the time of injury;
  • Blood sugar level increases to make the organism energetic;
  • Gastrointestinal activities decrease or even stop totally;
  • Blood is canalized from stomach and intestine to the motor organs and brain;
  • The hairs stand on their roots.

All bodily changes during emotions are the result of a number of complex underlying processes originating in and integrated by the Autonomic Nervous System, the endocrine glands and the cerebrospinal system. (Activities of the Autonomic Nervous System have been described in detail later in this chapter), these internal reactions are quite complex and difficult to measure.

The outward bodily changes include changes in facial expression, vocal expression, sweating on the surface of the body, and accelerated motor activities, etc. The internal physiological changes include changes in the electrical activities of the skin, respiratory activities, blood pressure, pulse -ate, sweat glands, reactions of the endocrine glands, and the chemical activities of blood etc.

The following instruments are used separately or in combination to measure organic changes during emotion: (i) the polygraph, (ii) multichannel amplifier with associated ink writing, (iii) optical oscillographs, (iv) pneumograph, (v) sphygmomanometer, (vi) psychogalvanometer, and (vii) electroencephalogram.


In addition to these instruments, damages in the brain such as paralysis on any lobe of the cerebral cortex due to emotional shock can be diagnosed by modern computerized instruments such as CT scan, PET scan and MRI (Magnetic Resource Imaging). The electrical activities of the body during emotion such as brain waves, muscle action potentials, galvanic skin responses, electro grams, and eye blinks are studied through these aforesaid instruments.

The following organic or physiological changes occur during emotion.

Electrical Phenomena of the Skin

One of the common measures of autonomic activities associated/affective and emotional state is the “galvanic skin response” (GSR). It also bears several names, such as ‘psychogalvanic reflex’, ‘skin resistance ‘Palmer resistance’, ‘Palmer conductance’, ‘electrodermal response’ and ‘ potential’. The GSR is measured with an apparatus known as psychogalvanometer. The changes in GSR called the electrodermal changes result from the activity of the sweat glands. The GSR is associated with blood pressure and respiration, and indicates that an emotional reaction is taking place. The GSR is activated during emotion by the sympathetic nervous system and decreases during emotional stimulations. The latency, amplitude, and duration of the GSR provide indications of whether or not an emotional reaction is taking place.


Blood Pressure

Darrow (1936) used blood pressure and galvanic skin reflex as indicators of emotional states. The level of blood pressure and GSR are considered be the best indications of facilitative, preparatory, and emergency functions during emotion activated by the sympathetic system.

There are two measures of blood pressure, i.e., systolic and diastolic. The difference between these two measures is known as “pulse pressure”. Systolic pressure is maximal pressure reached during the contraction of the heart; diastolic pressure is the least pressure during expansion. Variations in pressure owing to emotion are recorded continuously. The significance of these changes is correlated with emotional manifestations of the individual.

Heart Rate


The electrocardiogram (ECG) records the heart rate by means of attachment of electrodes to the two arms or to either of the arms and the left leg. The pattern recorded enables the cardiologist to analyze the performance of the heart during the emotional state. The “cardiotachometer” is a useful device for counting the number of heartbeats. “Cardiochronograph” is also another such device to study the heartbeats during emotion.


The respiration pattern is very often disturbed by emotional conditions. The respiratory features, i.e., the rate, depth, pattern, and inspiration and expiration ratio are measured in order to gauge the intensity of the emotional state. Respiration is mainly regulated reflexively through the respiratory center in the medulla. The medulla responds to changes in blood chemistry. Even if the respiration is interrupted by other reflexes, such as, coughing, sneezing, sighing, and yawning, it is a sensitive indicator of emotional responses such as the startle response, the conscious attempts at deception, and conflicts.

Skin Temperature


The common method to measure skin temperature in emotion is to apply thermocouple to the skin area concerned. Emotional stress produces a fall the skin temperatures. Conflict and altercations are associated with vasoconstriction and a fall in the skin temperature. On the other hand, uninhibited action and emotional security are said to result in vasodilation and crease in skin temperature.

Pupillary Response

The sympathetic and parasympathetic divisions of the Autonomic Nervous system never act together. Either of the two becomes active at one time spending on the situation. That means the two divisions are in active (position to each other while in action. Pupil of the eyes is the index of this. During emotion, dilation of the pupil occurs through the sympathetic system. Constriction of the pupil occurs by the parasympathetic system. Pupillary responses to pain and emotion-provoking stimuli have been studied by Bender (1933), Lindsley and Sassaman (1930). They recorded pupillary reaction during emotion, which are recorded through motion pictures. (This is the same modern video-tape recording).

Salivary Secretion


The secretion of the parotid gland has been studied by Pavlov and others in conditioning experiments. Wenger and Ellington (1943) described a method measuring salivary output as an index of autonomic activity. Others have tried to study the secretion of parotid gland in psychoneurotic patient’s response auditory stimulation. The secretion resulting from parasympathetic stimulation is thin and watery. But owing to sympathetic stimulation the salivary secretion becomes thick and is filled with mucus. This leads to the general observation that emotional excitement, anticipation, fear and anger produce dryness the mouth due to predominance of sympathetic activity.

Pilomotor Response

During emotion, especially when one is afraid of, hairs stand on their root. This is due to the activities of the sympathetic nerves. The production of “goose flesh” when one is afraid is an emotional reflex.

Blood, Saliva and Urine Analysis


Chemical components of the blood have been found to be affected by emotional stimulation. Among them are blood sugar level, adrenaline content, acid balance (pH), red blood ceils, and many other constituents. Tests have been made to know which organ of the body is activated when glucose and insulin are injected into the body. It was known that due to glucose and insulin intake, the sympathetic division becomes most active. Urine is analyzed for excess sugar secretion from samples taken at intervals before, during, and after emotional stimulation. The secretion of ketosteroids, a metabolic product resulting from steroid flow from adrenal cortex during stressful emotion, and the acid base balance (pH) have been found to vary with emotional state and stressful mental activities.

Gastro-intestinal Activities

Studies have been made on the activities of the stomach and the intestine in animals under emotional, electrical, and chemical stimulation. Cannon (1929) demonstrated that emotions of fear or anger inhibit activities in the gastro-intestinal tract. X-ray and fluoroscopic examination following barium milk, and by means of inflated stomach-balloon with a recording device a used to measure such gastro-intestinal activities.

Metabolic Rate

The amount of oxygen consumption or the basal metabolic rate (BMR) generally increases during emotions involving excitement and general body mobilizations. A standard BMR machine is used for the purpose.

Muscle Tension

A common symptom of emotional anxiety is bodily tension. These somatic reactions are caused by emotional reactions. Muscular tensions and visceral changes occur in emotion. Muscular tensions are recorded by means of muscle-action potential. Studies by Davis (1938) and Courts (1942) reveal relation of muscular tension to frustration and performance.


The emotional excitements such as fear and anger give rise to tremors. Tremor is witnessed in conditions of tensions. Luria (1932) found that emotional conflict externalized in motor performance led to tremor and disorganization of motor responses. Berrien (1939) has described finger-tremors as indices of emotion.

Eye Blinking

The excessive eye blinking is associated with emotional tensions. Too much eye blinking seems to suggest a kind of “nervousness”. The rate of eye blinking increases with emotional arousal and excitement. Records of eye blink shows there are different patterns of blinking in different people; in some, there may be continuous blinking; in others sporadic groups of rapid blinks; and in some others blinks may occur singly or doubly at irregular intervals.

Besides the aforesaid organic changes, which are associated with emotional sates, there are neural and hormonal mechanisms underlying emotional behavior. These can be understood by studying the activities of Autonomic Nervous System.