Nathan J Gordon, William L Fleisher Read online

  not usually under conscious control. Right now, you are not telling your heart, “Beat,

  beat, beat,” yet your heart is beating. You are not thinking, “Breathe, breathe,

  breathe,” yet you are breathing. These functions are being controlled through your

  autonomic nervous system. The autonomic nervous system is divided in its

  functions: the parasympathetic nervous system (PNS) and sympathetic nervous

  system.

  (i) The parasympathetic nervous system is the “housekeeping” or braking system.

  It is responsible for conserving energy and making sure necessary bodily

  functions such as digestion and waste elimination take place. It also functions

  3. PSYCHOPHYSIOLOGICAL BASIS OF THE FORENSIC ASSESSMENT

  19

  to restrain sympathetic arousal and attempt to maintain homeostatic norm.

  In doing so, it conserves physiological resources.

  (ii) The sympathetic nervous system is our emergency or action system. It is the

  system that causes the sudden and dramatic changes manifested in the example

  cited previously.

  The brain is in constant struggle with various psychological and physiological stressors to

  maintain or regain homeostasis through managing the competition of the parasympathetic

  and sympathetic nervous systems. The brain slows the heart down by sending it a parasym-

  pathetic neural message, or speeds it up by sending it a sympathetic message. It is constantly

  performing a cardiac-output physiological balancing act.

  Generally, the parasympathetic nervous system increases abdominal activity, allowing

  for digestion and waste elimination, while it slows thoracic (chest) activity and conserves

  energy by slowing the heart rate, lowering blood pressure, and decreasing the rate of

  breathing. The sympathetic nervous system decreases abdominal activity (there is no need

  for digestion or waste elimination under conditions of dire threat) and increases thoracic

  activity in an attempt to get more oxygen to the critical areas of the body necessary to assist

  in survival (Figure 3.1).

  Thus, the parasympathetic nervous system is constantly trying to balance the activity of

  the sympathetic nervous system in order to conserve energy and prevent bodily dysfunc-

  tion. However, frequently its efforts are defeated. When this occurs, sympathetic arousal

  takes place, causing sudden involuntary changes to prepare for the threat. The heart rate

  is increased and additional levels of adrenaline are secreted into the blood. The combination

  of an increase in cardiac output and adrenaline causes an increase in blood pressure. Addi-

  tional red blood cells are released from the spleen to increase the amount of oxygen deliv-

  ered to the body cells and remove the additional waste products produced by the excited

  metabolism.

  The underlying physiology is also stressed. The liver, fat, and muscle tissue which store

  energy as glycogen are infiltrated by adrenocorticotropic (ACTH) hormones. These hor-

  mones immediately help convert energy stored in these areas to actual energy to be

  released into the bloodstream. Research has established that ACTH also affects mind func-

  tion and improves memory. Endorphins, which are natural narcotics, are simultaneously

  released into the bloodstream (this pseudopharmaceutical mechanism assists us in not

  experiencing pain from injuries incurred until after the fight). The endorphins also help

  FIGURE 3.1 Overview of parasympa

  Increases

  Increases

  thetic/sympathetic controls of the body.

  abdominal activity

  thoracic activity

  Sympathetic

  Parasympathetic

  Decreases

  Decreases

  abdominal activity

  thoracic activity

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  3. PSYCHOPHYSIOLOGICAL BASIS OF THE FORENSIC ASSESSMENT

  you overcome your fear of the situation. Clotting enzymes are released to prevent profuse

  bleeding. There is vasoconstriction of the peripheral arterioles, which redirects the blood

  supply away from the skin surfaces to other parts of the body (this decreases the amount

  of blood that will be lost in case of injury, and causes the “ghost white” appearance often

  observed in people experiencing fear).

  In conjunction with the foregoing changes, there will also be a combination of differen-

  tiated vasoconstrictions and vasodilatations, as blood is rerouted from areas of less impor-

  tance to areas of primary importance in the body, or the body’s core, during the emergency.

  There is an increase in sweat gland activity to help cool the body down and act as a lubri-

  cant to help prevent abrasions during a fight. Palmar sweat (moisture in the hand) also pro-

  vides for a better grip. The hair may stand on end (piloerection or goose bumps). This

  physiological mechanism of raising the hair helps cool the skin surface, allowing air to cir-

  culate more freely over it. In earlier periods of our species evolution – before clothing – this

  hair “standing on end” may have served to make us look larger, fiercer, and less palatable

  to predators (Figure 3.2).

  The interaction of the two branches of the autonomic nervous system is clearly seen and

  felt (Figure 3.3). Sympathetically, visual and hearing acuity increase, maintaining the individual in a heightened state of awareness. As the pupils dilate, more light is admitted,

  extending far vision. Sympathetically, the salivary glands are inhibited. They are part of

  the digestive system and considered unimportant during fight/flight. This causes the

  “dry mouth” phenomenon utilized by earlier cultures in trials by ordeal.

  Some research suggests that memories imprinted during this heightened mental state are

  more vivid and may account for “reliving” and highly accurate recall experienced by trau-

  matized individuals. Others may argue that the endorphins may explain why victims of

  traumatic injury often do not remember it. Whichever occurs, one thing is certain: the

  mind-body’s sympathetic arousal during a threat is a highly evolved process designed to

  totally protect the individual during emergencies and afford it the best chance for survival.

  The parasympathetic nervous system is the “ying” to the sympathetic nervous system’s

  “yang.” Its job is to bring the body back into homeostasis – to conserve precious energy to

  FIGURE 3.2

  3. PSYCHOPHYSIOLOGICAL BASIS OF THE FORENSIC ASSESSMENT

  21

  Parasympathetic

  Sympathetic

  Constricts

  Eye

  Dilates

  Stimulates

  Salivary glands

  Inhibits

  Slows

  Breathing

  Increases

  No comparative

  Sweat glands

  Increases

  Slows

  Heart

  Accelerates

  Stimulates

  Digestion

  Inhibits

  Stimulates

  Waste elimination

  Inhibits

  FIGURE 3.3 The autonomic nervous system.

  “calm” the physiological seas, so to speak. If the parasympathetic nervous system should

  overcompensate as it attempts to return the body to its prethreat norm, involuntary urination

  or even defecation may result. Many police officers have often taken note of how, on occa-

  sion, th
ey responded to the scene of a burglary only to find human feces in the middle of

  the floor. Some people theorize that this defecation is sexually or socially related behavior,

  but it is likely that it is caused by the overcompensation of the parasympathetic division,

  after the strong sympathetic arousal caused by fear of detection associated with committing

  a burglary. This overcompensation explains why people sometimes faint during extreme

  emergencies, and why deceptive suspects often display leaning/supportive behaviors.

  Although the forgoing example was one of perceived physical threat, the responses to

  psychological or even supernatural threat are similar. A guilty suspect may become weak

  in the knees or appear to lose balance and have the need to support himself during the per-

  iods of greatest threat. Extreme sympathetic and parasympathetic arousals appear most

  obviously in cases where there are reports of death caused by “voodoo” curses. Victims

  who strongly believed they had been cursed would die after displaying chronic symptoms

  of fright (sympathetic arousal), which depleted their adrenaline, causing death due to low

  blood pressure [2]. Alternatively, sympathetically/parasympathetically induced voodoo

  death can also be caused by hypovolemic shock. This results from the constant heightened

  state caused by sympathetic arousal: victims’ intestines lack the necessary blood and fluids

  to sustain cell life, and organ necrosis and death results. Whichever explanation applies in a

  given instance, these cases clearly validate the General Adaptation Syndrome postulated by

  Hans Selye, a Canadian physiologist [3], and the need for the body to be able to regain a homeostatic norm.*

  *Selye reported that on experiencing distress, the body entered an “alarm” stage, where psychophysiological

  factors were heightened. The body next entered a stage of “resistance,” where it attempted to overcome the

  distress. If the body was unable to correct the problem, it entered into a stage of “exhaustion,” which

  ultimately led to death.

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  3. PSYCHOPHYSIOLOGICAL BASIS OF THE FORENSIC ASSESSMENT

  Usually alterations to the body’s homeostatic norm are not drastic or life threatening.

  They are, however, clearly measurable, and measuring changes in three of the body’s sys-

  tems is the basis for the polygraph examination. During a polygraph examination, the

  examinee is attached to the polygraph instrument, and several charts of data are collected

  while the examinee answers only “yes” or “no” in response to the questions asked. Requir-

  ing only yes or no answers minimizes vocalization and subsequently reduces distortion cre-

  ated in the breathing pattern of the examinee, which is inherent in prolonged speech

  patterns. In addition to breathing, the polygraph instrument records electrodermal skin

  activity and cardiovascular changes, such as changes in pulse rate, mean blood pressure,

  and blood volume [4].

  Moreover, the same physiological changes, in one degree or another, that are recorded

  on a polygraph instrument also appear during the telling of a lie in an interview when

  the subject experiences undue stress caused by the fear of detection. While the polygraph

  technique elicits one series of measurable changes, consider the greater number of

  additional, observable physiological changes suppressed using this technology. Many phys-

  iological changes caused by the tremendous energy and strength the body is producing

  during this heightened state of arousal, which would cause changes in body position and

  nonverbal behavior, cannot be assessed because of the subject’s instructions to sit still.

  The forensic interviewer, on the other hand, is not limited only to observing changes in

  the three physiological parameters that the polygraph monitors. He or she is trained to

  make global use of the senses to detect leakage of deceptive behavior, regardless of how

  it occurs, during the Forensic Assessment Interview. Understanding why these changes

  occur and how to recognize them will enable the reader to determine truth or deception

  and separate innocent from guilty suspects.

  It is a given that the sympathetic nervous system kicks into action whenever the

  brain perceives a threat. In considering data presented to the interviewer as a result of

  sympathetic enervation, we should be aware of the work of W. B. Cannon. Cannon, a famous

  Harvard psychologist, reported that when a cat was fed a meal containing a radiation-opaque

  substance and placed on a table so an x-ray of its stomach could be taken, digestion went on

  normally. The cat’s stomach made rhythmic movements known as peristaltic action. When a

  dog was brought into the room, which represented a threat to the cat’s well-being, the cat

  became sympathetically aroused, and its digestion suddenly ceased.

  The question remains: Why does telling lies constitute a threat significant enough to

  cause this sympathetic enervation? There are several theories for this cause–effect relation-

  ship. They include conditioning, approach-avoidance conflict, and psychological set (also

  referred to as “salience”) [5].

  Classical or Pavlovian conditioning [6] was discovered by the Russian physiologist Ivan

  Pavlov, while he was attempting to study salivation in dogs. To start the dogs salivating,

  Pavlov presented them with food. His experiments were disrupted when just the sight of

  him or his assistants caused the dogs to begin salivating even before food had been pre-

  sented. Pavlov realized that salivation could be psychologically caused; and, he had taken

  on a special relationship with food in the minds of the dogs. Every time he had previously

  entered the room the dogs were presented with food. Now, just the sight of him caused

  salivation.

  3. PSYCHOPHYSIOLOGICAL BASIS OF THE FORENSIC ASSESSMENT

  23

  Pavlov called the presentation of food an “unconditioned stimulus” (UCS), which he

  described as any stimulus capable of causing a reaction to occur without any prior training

  or learning having taken place. Pavlov labeled the reaction or response that occurred when

  a UCS was presented an “unconditioned response” (UCR). In Pavlov’s chance discovery,

  food was the UCS, and salivation was the UCR. Pavlov theorized that if a neutral stimulus

  (NS), such as himself, were paired enough times with a UCS (i.e., food), then the NS would

  take on the properties of the UCS and cause the UCR (i.e., salivation) to occur, even though

  the UCS was not present. The neutral stimulus had become a “conditioned stimulus” (CS),

  and the UCR was now a “conditioned response” (CR) (Figure 3.4).

  When a child is caught doing something “wrong” (wrong behavior can be very subjec-

  tive) by his parents, he is yelled at, disapproved of, spanked, or in some other way pun-

  ished. This automatically causes sympathetic arousal to occur. Punishment is the UCS,

  and sympathetic arousal is the UCR. Throughout our lifetimes, when we tell self-serving

  lies and get caught, we are punished. Lying, therefore, becomes associated or paired with

  punishment. It becomes a conditioned stimulus (CS), which can then cause a conditioned

  sympathetic arousal to occur (Figure 3.5).

  A second explanatory theory is that of “conflict” [5]. Anytime mental conflicts occur, we experience emotional changes that, in turn, ca
use physiological changes to occur. If you

  have the choice of going to a movie or to a football game, and you really want to do both,

  you are experiencing an approach-approach conflict. The greater your desire to attend both

  events, the greater the conflict would be, and the greater the resulting physiological changes

  that will be created. Avoidance-avoidance conflict results from having to choose between

  two negatively impacting options. The greater the negative impact of the options, the

  greater the accompanying physiological response.

  FIGURE 3.4 Classical/Pavlovian conditioning.

  Food

  Salivation

  (UCS)

  (UCR)

  Pavlov

  (Neutral stimulus)

  FIGURE 3.5 Conditioned response to a lie.

  Punishment

  Sympathetic arousal

  (UCS)

  (UCR)

  Caught telling a lie

  (CS)

  24

  3. PSYCHOPHYSIOLOGICAL BASIS OF THE FORENSIC ASSESSMENT

  When an action causes something desirable or undesirable, with neither being predict-

  able, it is called an approach-avoidance conflict. A laboratory rat in a Skinner box** is taught that by pressing a lever it will receive a reward of a food pellet. When the experimenter unpredictably alternates the outcome by intermittently introducing a punishment

  of an electric shock when the lever is pressed, the rat does not know whether it will be

  rewarded with food or punished with an electronic shock. The rat wants to receive food,

  but fears receiving an electric shock, and it now experiences an approach-avoidance con-

  flict, because the same action can produce either outcome.

  Like the rat in the Skinner box, an individual telling a lie also places himself in an

  approach-avoidance conflict. He is asked a question by the interviewer and answers with

  a lie. If he gets away with his deception, he is rewarded. If his lie is detected, he is punished.

  He is unsure what the result will be. The greater the reward and punishment, the greater

  the mental conflict will be, and the greater the accompanying sympathetic arousal.

  A third possible theory involves the psychological concept of cognitive dissonance.

  When a person holds two contradictory ideas simultaneously, he will experience an uncom-

  fortable feeling [7]. The “ideas” or “cognitions” in question may include attitudes and

  beliefs, the awareness of one’s behavior, and facts. This theory is one of the most influential