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Handler, Nelson, Krapohl & Hontsexhalation ratios between truthful anddiscontinuous blood pressure measurement todetermine when an examinee was engaging indeception, a practice that became the focus ofthe famous case of the United States v. Frye.The Frye decision ultimately set the standardfor the introduction of scientific evidence intolegal proceedings in the U. S. Federal Courtsfor 70 years. Larson combined aspects of theBenussi and Marston approach, improving onboth in terms of instrumentation and theory.Larson developed a polygraph capable ofrecording continuous relative blood pressurepressure changes, pulse rates and movementassociated with breathing in 1921 (Trovillo,1939).garnered enthusiastic support only fromthe creator of the technique. ReverendSummer'sPathometerencounteredlimited general use.” (p. 7).Leonarde Keeler is commonly givencredit for adding the EDR component, therecording of respiration, and relative bloodpressure as early as 1949 (Reid & Inbau,1977). Trovillo (1939), reported that Wilson, acolleague of Keeler, actually developed apolygraph that simultaneously recorded thethree channels of respiration movement,cardiograph and electrodermal activity inapproximately 1930. With the exception of aphotoelectric device to record vasomotorchanges, these components have remainedthe primary psychophysiological channels fordetection of arousal associated with deceptionsince the 1930s.One of the earliest records of the use ofEDRs to detect deception was by AlfredStickler in approximately 1897, which hedescribed in his contribution to Carl Jung'sbook Studies in Word Association (1919).Larson (1932), credits Chester Darrow withadding a skin resistance measurement toearly polygraphs and experimented with agalvanometer himself, but reportedly decidedto forego its use in favor of cardiographic-typeresponse measurement. Marston (1938),reportedly experimented with the EDRcomponent while devising deception tests forthe United States Army in 1917, but wrotethat he was unimpressed with the lack ofspecificity to deception. Marston realized thatnumerous emotional arousals could, and did,cause EDRs.Anatomy and Physiology of the Skin3The skin is called the integumentarysystem and consists of a complex set oforgans that provide protective and sensefunctions. Skin protects the body fromenvironmental threats such as temperature,chemical, mechanical and infectious agents byacting as a selective barrier. Skin can aid inthe removal of substances like water andsolutes from the bloodstream through thesweat glands. From a sensory standpoint, skinhouses various receptors to provide afferentinformation related to touch, pain andtemperature (Venables & Christie, 1973).Reverend Walter Summers (1936),reported high levels of sensitivity to deceptionwhen using EDR measurements in both alaboratory setting and in limited criminal fieldapplications. Krapohl (1993) comments;In many areas, skin allows forperspiration, which helps keep the skin moistand may contribute to flexibility, though thisis less likely on the plantar and palmarsurfaces (soles of the feet and palms of thehands). These areas have increased potentialto be subjected to load bearing and frictionand are considerably thicker, 600 microns ascompared to the 15 microns found in manyother areas (Venables & Christie, 1973). Skinalso helps maintain a constant bodytemperature by controlling heat loss which is“Summers usedhisdevice andtechnique on only about 50 criminalsuspects and he claimed tremendoussuccess, though his verification of thoseresults would not stand up to currentstandards of proof. His work, like thatof Lombrosso and Marston, hadThe material in this section is derived from the major scientific sources describing the Anatomy and Physiology ofthe skin (e.g. structure of the skin). Readers interested in the original scientific sources should see: Boucsein, 1992;Fowles, 1986; and Venables & Christie, 1973.371Polygraph, 2010, 39(2)

Electrodermal Activityregulated by adjusting blood flow to areasnear the surface of the skin and throughthermoregulatory sweating. Increasing bloodflow near the surface allows for cooling of thepassing blood and this cooling is then passedon to lower lying tissue. Thermoregulatorysweating cools the surface of the skin byremoving the latent heat when liquid waterevaporates on the surface of the skin. Atpalmar and plantar sites thermoregulatorysweating occurs only in relatively highambient temperatures (upper 80s F). Sweatglands on the soles and palms are moreresponsive to central nervous system (CNS)activation than to ambient temperaturechanges.include; nerve cells called Meissner's andVater-Pacini corpuscles that transmit thesensations of touch and pressure, hairfollicles with their associated oil and scentglands, erector pili muscles that attach toeach hair follicle, blood vessels and nervesthat transmit sensations of pain, itch, andtemperature, and eccrine sweat glands, whichare the putative source of EDRs.Beneath the dermal layer lies thesubcutis, also called the hypodermis, whichattach the skin to connective tissue coveringthe muscles. This is also where the secretorypart of the eccrine sweat gland may lie, alongwith blood vessels and nerves supplying therest of the skin. When located here, thesecretory portion of the eccrine sweat gland isembedded in fatty tissue and is supplied bythe capillary network of that area with waterand electrolytes (Boucsein, 1992). For thelocation of these structures, as well as thegeneral location of the various layers of skin,see Figure 1.Skiniscomposedofvariouscharacteristic layers, though all layers are notuniformly found in all skin. Skin can be hairyor glabrous (hairless). Skin essentiallyconsists of two main layers; an outer layercalled the epidermis and a thicker lower layer,the dermis. The epidermis of glabrous skin asfound on the palm is generally divided intothree regions which compose five layers witheach layer becoming progressively tougherand calloused toward the surface. Thestratum malpighii region is comprised of thetwo deepest layers of the epidermis which arethe strata germinativum, and spinosum. Thestratum intermedium region consists of thestratum granulosum, and stratum lucidum.The latter is recognizable in limited body sites,primarily in palmar and plantar skin and isvisible only if the horny layer is removed. Theoutermost region is called the stratumcorneum and can be divided into a lower,middle and upper zone based upon the formof the cells and the space between the cells,which decreases as it approaches the surface(Boucsein, 1992).Sweat Gland Types, Distribution andProperties4Humans have two basic types of sweatglands, apocrine and eccrine. Apocrine sweatglands are large in size, discharge into hairfollicles, and become active during puberty.They are mainly found in the armpit andgenital areas and are not the source of theEDRsmeasuredandevaluatedinpsychophysiology or polygraphy. Eccrinesweat glands, on the other hand, aredistributed throughout the body, but most areconcentrated on the palms, soles and foreheadand least dense on the arms, trunk and legs.Estimates place the number of eccrine sweatglands between 2 and 5 million (Fowles, 1986)and the total number of sweat glands is fixedat birth.The thicker layer of skin, the dermis,consists of two main parts; the papillary layerwhich contains a thin arrangement of collagenfibers and the thicker reticular layer, of thickcollagen fibers that are arranged parallel tothe surface of the skin. The dermis containsmany specialized cells and structures. TheseThey are called eccrine because theycontain comparatively little gland cellcytoplasm(thewaterbased,jelly-likesubstance that fills the cell). The eccrine sweatgland consists of a coiled secretory portionThe material in this section is derived from the major scientific sources describing sweat gland physiology anddistribution. Readers interested in the original scientific sources should see: Boucsein, 1992; Fowles, 1986; andVenables & Christie, 1973.4Polygraph, 2010, 39(2)72

Handler, Nelson, Krapohl & HontsFigure 1. Anatomy of the skin. Pope, Amy E. Anatomy and Physiology for Nurses (New York: G. P.Putnam's Sons, 1913) 439. Clipart courtesy FCIT, http://etc.usf.edu/clipart. Retrieved 9February, 2010, from http://etc.usf.edu/clipart/52300/52321/52321 skin.htm.(glomerulus) about .4 mm in diameter (seeFigure 2) located in the subdermis and aductal discharge tube that winds its waythrough the dermis and then follows a spiralcourse through the epidermis terminating at apore on the skin surface. Both the secretoryand most of the ductal segments are formedby two-to-three layers of cells (Figure 2). Thewall of the ductal tube that passes throughthe epidermis is called the acrosyringium andit has no cells in its walls. Essentially it is acoiled duct surrounded by yringium has no wall cells (see Figure 2),it is possible for sweat working its way up theduct through the epithelium to escape theductal tube without being deposited on thesurface and hydrate the corneum (Fowles,1986). If the corneum adjacent to theacrosyringiumisadequatelyhydrated,discharge from the tube may then be directedto the surface of the skin. As the corneumbecomes hydrated with ion-laden sweat, itsability to conduct a current will increase.When the sweat glands are completely full ofsweat, however, the electrical conductance ofthe skin is presumed to increase markedly(Boucsein, 1992).73Polygraph, 2010, 39(2)

Electrodermal ActivityFigure 2. Layered construction of human skin shown in relation to the eccrine sweat glandincluding the secretory portion, the straight duct and the acrosyringium. Adapted from Chancellor,William E. Standard Short Courses for Evening Schools (New York: American Book Company, 1911)244. Clipart courtesy FCIT, http://etc.usf.edu/clipart. Retrieved 9 February, 2010, fromhttp://etc.usf.edu/clipart/44000/44013/44013 skin.htm.The Sweating Action of the Eccrine SweatGlands5study them individually. The sudorisecretoryfibers surround the secretory part of theeccrine sweat gland and use acetylcholine forinnervation. No synaptic clefts have yet beenidentified and it is presumed that theneurotransmitter substance is released in thevicinity of cholinergic receptors on thesecretory cells resulting in their depolarizationand activation (Boucsein, 1992).Efferent fibers from the sympatheticnervous system innervate the eccrine sweatglands secretory segment and dermal portionsof the duct. These sudorisecretory fibers areintermeshed with fibers innervating piloerector muscles of the hair and fibers thatinnervate blood vessels, making it difficult toThe material in this section is derived from the major scientific sources describing sweating action of eccrine sweatglands. Readers interested in the original scientific sources should see: Boucsein, 1992; Fowles, 1986; and Venables& Christie, 1973.5Polygraph, 2010, 39(2)74

Handler, Nelson, Krapohl & HontsHuman precursor sweat containsrelatively high concentrations of sodium (Na ),potassium (K ) and chloride (Cl-), all of whichare vital to life. By the time the sweat reachesthe surface of the skin, the concentration ofthose very important ions has been reduceddrastically, presumably through the processesof active and passive reabsorption. Activereabsorption has been compared to the sameaction that occurs in the renal tubules of thekidneys (Boucsein, 1992). Relative to theinterior of the body, sweat has fewer ions ofsodium and chloride and is thus referred to ashypotonic. The concentration of surface sweatvaries with the rate of sweating, presumablyreflecting a limited reabsorption capacity(Fowles,1986).Theincreasedionconcentration during higher sweat rates maycontribute to EDA changes. Reabsorption isthought to take place primarily in the dermalduct but also in the acrosyringium. Throughthe process of reabsorption, sweat gland ductsmay help to protect the body from excessiveion loss during periods of profuse sweating.There is considerable evidence to suggest thatsodium is reabsorbed via an active sodiumpotassium pump. Sodium is exchanged withpotassium resulting in an increase inpotassium concentration in surface assivelydiffusesdownitselectrochemical gradient to be reabsorbed(Fowles, 1986). While the chemical chlorideion gradient tends to oppose diffusion, thesomewhatgreaterelectricalpotentialfacilitates it, resulting in passive ine. When the coil contracts, thelumen dilates slightly and stays dilated untilthe innervation ceases. Presumably, thiscontraction of the glomerulus and dilation ofthe lumen contribute to movement of thesweat up the duct towards the surface of theskin. Sweat does not flow constantly from thesecretory portion of the gland onto the skinsurface. Rhythmic contractions of cellssurrounding the secretory and ductal part ofthe gland have been observed to create sweatpulses at rates of around 20 cycles per second(Boucsein, 1992) which may help move thesweat up the duct towards the surface pore.Suggested Biological Significance of EDA6The biological significance associatedwith EDRs has been proffered in terms ofevolutionary benefits. Explanations of thebenefits of EDRs seem consistent with anumber of psychological underpinningsdiscussed later in this paper. Edelberg (1972)suggested that thermoregulatory responses toemotionallyarousingstimulimaybeallostatic7 in nature. Evaporative sweatingmay serve to decrease body temperature inanticipation of an upcoming burst of physicalactivity. Emotionally arousing stimuli, resultin vaso-constriction which leads to areduction in skin blood flow. An adaptivepurpose of this vasoconstriction is to increasesystemic blood pressure for increased largemuscle perfusion. There is an additionalbenefit of reducing cutaneous blood lossshould a cut occur during the state of arousal.Cutaneous blood flow plays a part in thermalregulation so a reduction in surface blood flowcould lead to a rise in body temperature.Perhaps evaporative cooling via EDRs helpscompensate for the reduction in heat lossresulting from vasoconstriction.Sato (1977) discovered that whensecretory coil is not being stimulated, thelumen is almost completely collapsed. Thiswould suggest there was an insufficientquantity of pre-formed sweat in just theresting lumen to reach the sweat pore openingand cause EDRs without some sweatcontribution from the glomerulus. What Satodiscovered was that when the glomerulus(secretory coil) is innervated, it contracts toabout two-thirds of its original length within aIncreased palmer perspiration mayallow for better tactile differentiation (Darrow,1933), better hand grip (Boucsein, 1992;Darrow, 1933), and protection against injuryThe material in this section is derived from the major scientific sources describing some of the possible biologicalsignificance of sweat glands. Readers interested in the original scientific sources should see Edelberg, 1967.6Allostatic refers to the maintenance of homeostasis through physical or behavioral response. A resource for readersinterested in allostasis as it relates to polygraphy can be found in Polygraph, 37(3), 228-233.775Polygraph, 2010, 39(2)

Electrodermal Activity(Adams & Hunter, 1969). Increased g, 1967; Boucsein, 1992) an obviousbenefit to bare foot runners and tree climbingprimates.electrical current to flow directly) from thesurface of the skin to and through therelatively moist dermal layers. For any givenlevel of corneal hydration, changes in theheight of the sweat in the duct will modify theresistance across the corneum: the ductworks like a variable resistor. Edelberg (1983)demonstrated how the level of sweat in theduct at innervation has a marked effect onEDR amplitude. Edelberg manipulated thelevel of sweat in the duct prior to innervatingthe gland and measured the results. Theconclusion was that higher initial levels ofsweat in the duct produced EDRs of greateramplitude, in fact at times tripling theresponse.EDA and the Electrical Properties of Skin8There is ample empirical evidence tosupport the notion that sweat gland activitycontributes to the phenomena of EDA, emodelforexplanation. Sweat moistened epidermaltissue contains ions which increases skinconductivity. The layers of skin below theepidermis show good electrical conductivityand do not contribute to skin resistancechanges measured during an EDR (Boucsein,1992). Most electrical models of skin assignthe role of a variable resistor to the entirestratum corneum, relative to its degree ofhydration. The dead cells of the stratumcorneum act like a sponge, taking in moisturefrom above (outside the body or from anyelectrolyte solution) and below (from withinthe body). The stratum corneum is usuallypartially hydrated and the degree to which itis hydrated will be the primary contributor toEDL. Changes in corneal hydration willgenerally result in tonic level changes of EDA,but also have an effect on the amplitude ofEDR (Fowles, 1986). Increased hydrationreduces resistance and increases conductancewhile a drier stratum corneum worksoppositely. When the corneum is eitherextremely hydrated or extremely dehydrated,EDRs are minimal. It is at intermediate levelsof corneal hydration that maximal levels ofEDRs are achieved (Stombaugh & Adams,1971).There are many proposed theories andmodels of the electrical properties of the skinand a number of those were reviewed byEdelberg (1972). No single model is completelytenable and stands on its own but mostaccept some general facts. EDRs require thepresence of active sweat glands. This fact thathas been substantiated by interrupting thesympathetic nerve supply to the sweat glandthrough chemical blockage or sympathectomy,as performed in efforts to alleviate a conditionknown as hyperhidrosis. In either case, theseaffect EDRs at the interface between the sweatgland and the sympathetic cholinergicinnervation occurring there. Beyond thispoint, it becomes difficult to specifically pointto the mechanism responsible for EDRs.Edelberg (1972) suggested the capacitanceproperties of the skin and sweat glandscontributed to the fast rise, phasic EDRs.When an external current is applied to theskin, the cell membranes can store electricalpotentials like a capacitor. Edelberg (1971)posited that larger cell assemblages may acttogether to selectively allow passage of certainions as if they were parallel capacitors. Thusthe phasic EDR response observed inpolygraphy could in part be due to membranedepolarization when the cells are collectivelyneurologically stimulated. The capacitiveproperties of skin and sweat gland ducts havenot been well investigated compared to thosethat are resistive in nature. This may be dueSweat secretions result in not onlycorneal hydration but also in filling of thesweat duct. Both duct filling and cornealhydrationleadtochangesinskinconductance, though duct filling is theprimary mechanism by which EDRs areelicited (Fowles, 1986). Filling the ductsresults in direct electrical shunts (allowsThe material in this section is derived from the major scientific sources describing the electrical properties of skin.Readers interested in the original s

An EDA Primer for Polygraph Examiners Mark Handler, Raymond Nelson, Donald Krapohl, and Charles R. Honts Introduction Of all the signals collected and analyzed during psychophysiological detection of deception (PDD) or polygraph testing, the electrodermal response (EDR) is the most robust and inform