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OVREDNOTENJE MERILNE NEGOTOVOSTI V PSIHOFIZIOLOŠKIH MERITVAH ZARADI ANKSIOZNOSTI UDELEŽENCA
GRŽINIČ FRELIH, NINA (Author), Geršak, Gregor (Mentor) More about this mentor... This link opens in a new window, Podlesek, Anja (Co-mentor)

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Abstract
Doktorska disertacija združuje metrologijo, fiziologijo in psihologijo z namenom ovrednotenja prispevkov k merilni negotovosti pri psihofiziološkem merjenju. V fiziološkem delu disertacija posega na področje merjenj v psihofiziologiji. V delu metrologije fizioloških spremenljivk (na primer prevodnost kože, srčni utrip, krvni tlak, temperatura kože, frekvenca dihanja) obravnava senzorje in pretvornike psihofiziološke instrumentacije, merjenje spremenljivk, meroslovno ovrednotenje senzorjev in pripadajoče merilne instrumentacije v smislu določanja vplivnih veličin na merilni rezultat ter ocenjevanje merilne negotovosti. Psihološki del disertacije obravnava področje senzorične metrologije oz. psihofizike, tj. vede o merjenju veličin, ki za razliko od klasičnih fizikalnih veličin, kot so električna prevodnost, tlak, temperatura, še nimajo splošno sprejetih referenc, etalonov, skal in enot. To so različne psihološke spremenljivke, npr. občutki različnih senzornih modalnosti, čustva in drugi psihološki konstrukti. Psihološki del disertacije zajema tudi opredelitev in merjenje anksioznosti kot stanja, od katerega je odvisna merilna anksioznost. Le-to obravnavamo kot poseben prispevek k merilni negotovosti. Prevodnost kože, temperatura kože in krvni tlak so ene izmed fizioloških funkcij, ki jih uravnava avtonomni živčni sistem. Njegovo delovanje je odvisno od psihofiziološkega stanja osebe. Bistvena značilnost avtonomnega živčevja je, da ga oseba ne more zavestno nadzirati, torej deluje neodvisno od volje osebe. Psihofiziološko stanje osebe je močno spremenljivo, zato lahko ob različnih časovnih trenutkih in v različnih psiholoških stanjih merjene fiziološke spremenljivke močno variirajo. Anksioznost se na telesni ravni odraža kot povečana aktivnost avtonomnega oz. simpatičnega živčnega sistema, kar vodi do mišične napetosti, odziva dihalnega aparata ter spremembe srčnega utripa in aktivnosti kože. Oseba jo doživlja kot neprijeten občutek napetosti, ki je običajno neopredeljen in nespecifičen. Močno izražena anksioznost med meritvijo lahko vpliva na rezultat meritve oz. meritev samo. V kolikšni meri anksioznost vpliva na rezultate, je v prvi vrsti odvisno od posameznika in njegovega trenutnega psihofiziološkega stanja. Ti vplivi niso zanemarljivi in jih lahko ob ustrezni identifikaciji in vrednotenju upoštevamo pri interpretaciji merilnih rezultatov psihofizioloških spremenljivk in nadaljnji diagnostiki. Za namen eksperimentalnega dela raziskave smo pripravili pregled merilne instrumentacije na področju fiziologije in psihologije. Z identifikacijo ustreznih instrumentov smo sestavili avtomatiziran sistem za časovno sinhronizirani zajem izbranih fizioloških in psiholoških spremenljivk. V programskem okolju LabVIEW smo izdelali virtualni merilni instrument za merjenje izbranih spremenljivk merjene osebe, ki je enostavno prilagodljiv na različne oblike merilnih protokolov. V nadaljevanju disertacija opisuje dva preliminarna eksperimenta (poglavji 3.4 in 3.5), na podlagi katerih smo izpeljali smernice za pripravo protokolov psihofizioloških meritev. V prvem eksperimentu smo opazovali vplive zaporednih meritev krvnega tlaka na psihofiziologijo merjene osebe. Z merilnikom za domačo uporabo smo izvajali 5 zaporednih meritev krvnega tlaka, ki so predstavljale motnjo, in opazovali spremembe krvnega tlaka, prevodnosti kože in drugih fizioloških spremenljivk merjene osebe. Potrdili smo, da najvišjo vrednost krvnega tlaka izmerimo ob prvi meritvi, prava vrednost pa je najbližja tretji meritvi. Povprečna razlika med njima je bila +2,1 mmHg za sistolično vrednost in +2,8 mmHg za diastolično vrednost. Vrednost krvnega tlaka v povprečju pada le do tretje meritve, za tem pa začne ponovno naraščati ali nihati. Odvisna je torej od števila predhodnih motenj. Zato bi tudi morebitno korekcijo končne spremenljivke morali izvajati ne glede na pretečeni čas od začetka meritve, ampak glede na število predhodnih motenj. Umiritveni čas psihofizioloških spremenljivk je namreč odvisen od višine začetne spremembe. Če je sprememba velika, bo fiziološka spremenljivka hitreje padla na osnovno raven, če je nizka, pa počasneje. V drugem eksperimentu smo se osredotočili na različne oblike merilnih metod za merjenje psihofizioloških spremenljivk in izbrane merilnike razvrstili v tri kategorije; neintruzivne merilne metode smo definirali kot merilne metode, pri katerih se merjena oseba ne zaveda, da je merjena/opazovana, manj intruzivne merilne metode predstavljajo metode, ki so sicer na začetku meritve moteče in se jih merjena oseba zaveda, a se jih s časom navadi in nanje pozabi, kot intruzivne merilne metode pa smo definirali merilne metode, pri katerih se merjena oseba zelo zaveda, da je merjena/opazovana. Z eksperimentom smo ugotavljali vpliv intruzivnosti uporabljenih merilnih metod v povezavi s spremembami psihofiziologije merjene osebe in njenega doživljanja merilne situacije. Rezultati so pokazali, da merjeno osebo med procesom meritve najbolj vznemiri nameščanje merilnikov in govor izvajalca meritve. Ti dogodki sprožijo največje odzive prevodnosti kože, medtem ko se v času reševanja vprašalnikov poviša raven prevodnosti kože. Intruzivnost merilnika je odvisna tudi od števila drugih merilnikov, ki jih sočasno namestimo na merjeno osebo. Iz teh eksperimentov sledi, da je potrebno pri merjenju fizioloških spremenljivk uporabiti čim manj merilnikov, najbolje samo enega, ki je obenem čim manj intruziven. Izvajalec meritve mora med meritvijo čim manj govoriti, najbolje nič ali pa sploh ni prisoten v prostoru. Vse vprašalnike je potrebno izvajati na koncu merjenja fizioloških spremenljivk. V povezavi s tipi osebnosti smo ugotovili, da so manj sprejemljive in bolj introvertne osebe bolj merilno anksiozne, zato je upoštevanje zgornjih omejitev pri teh osebah toliko bolj pomembno. Na podlagi zgornjih ugotovitev smo sestavili končni merilni protokol, ki je vključeval le tri meritve krvnega tlaka (motnje), merjenje vpliva motenj na prevodnost kože. Psihološke vprašalnike za merjenje osebnostnih značilnosti in samoocenjevalne lestvice smo umestili za meritvami fizioloških spremenljivk. Rezultati tega eksperimenta so podobno kot v prvih dveh eksperimentih nakazali, da so bili najbolj obremenjujoči dogodki v procesu meritve govor izvajalca in začetek reševanja psiholoških testov. Osebe, ki so bile med meritvijo bolj vznemirjene, je bolj vznemiril tudi posamezen dogodek znotraj merilnega procesa, še posebej je to veljalo za manj samozavestne osebe, ki so se bolj odzvale na določene motnje znotraj merilnega procesa. Analiza podatkov je pokazala tudi, da so bile merjene osebe bolj merilno anksiozne, ko je meritev izvajala oseba moškega spola. Rezultati tega eksperimenta kažejo na nižje vrednosti povprečnih odzivov merjenih psihofizioloških spremenljivk na vseh merjenih osebah. To lahko pripišemo naključnemu izboru oseb kot takih ali pa dejansko manj obremenilnemu protokolu meritve. Na podlagi vseh izvedenih meritev smo ovrednotili tudi merilne negotovosti klasične psihofiziološke meritve in pripravili predlog zmanjšanja merilne negotovosti psihofizoloških meritev. Ta je obenem osnova za pripravo neintruzivnega merilnega protokola psihofizioloških meritev. Zaključujemo, da neinvazivno merjenje krvnega tlaka z merilnikom za domačo rabo predstavlja intruzivno motnjo, ki zviša aktivnost prevodnosti kože za manj kot 1 μS in vpliva na vrednost krvnega tlaka samega. V povprečju sta se sistolična in diastolična vrednost krvnega tlaka ob prvi motnji povišali za manj kot 15 mmHg, pri čemer je bila merilna negotovost manjša od 10 mmHg. Povišanje vrednosti fizioloških spremenljivk je bilo bolj značilno za manj samozavestne in bolj introvertne osebe. Podrobna obravnava teh ugotovitev na večjem številu merjenih oseb predstavlja bodoče izzive na področju psihofizioloških merjenj.

Language:Slovenian
Keywords:psihofiziološke meritve, krvni tlak, prevodnost kože, merilna negotovost, merilna anksioznost, protokol
Work type:Doctoral dissertation (mb31)
Organization:FE - Faculty of Electrical Engineering
Year:2019
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Secondary language

Language:English
Title:ESTIMATION OF MEASURING UNCERTAINTY IN PSYCHOPHYSIOLOGICAL MEASUREMENTS DUE TO PARTICIPANTS ANXIETY
Abstract:
The doctoral dissertation combines metrology, physiology and psychology with an aim to estimate contributions to the measurement uncertainty in psychophysiological measurement. In the physiological part the dissertation deals with measurements in psychophysiology. In the part of the metrology of physiological variables (skin conductance, heart rate, blood pressure, skin temperature, respiration rate ...) the dissertation deals with sensors and transducers of psychophysiological instrumentation, measurements of variables, metrological evaluation of sensors and measuring instrumentation in terms of determining the influential quantities and estimation of measurement uncertainty. The psychological part of the dissertation deals within the field of sensory metrology or psychophysics, i.e. quantities that commonly, unlike conventional physical quantities such as electrical conductance, pressure or temperature, do not yet have generally accepted references, standards, scales and units. These are different psychological variables, e.g. feelings of different sensory modalities, emotions and other psychological constructs. The psychological part of the dissertation also includes the definition and measurements of anxiety as a condition. We consider the anxiety to be a contribution to the combined measurement uncertainty. Skin conductance, skin temperature and blood pressure are physiological functions regulated by the autonomic nervous system. Their operation depends on the person's psycho-physiological state. The essential characteristic of the autonomic nervous system is that in principle it cannot be controlled consciously by the person itself, so it acts independently of the person's will. The psychophysiological state of the person is highly variable, so the physiological variables vary greatly at different times and when in different psychological states. Anxiety is reflected as an increased activity of the autonomous (sympathetic) nervous system, leading to muscular tension, respiratory response and changes in heart rate and skin activity. The person experiences it as an unpleasant feeling of tension, which is usually difficult to define and non-specific. Strongly expressed anxiety can affect the result of the measurement or even the measurement itself. To what extent anxiety affects the results, it depends primarily on the individual and his/her current psychophysiological state. These influences are not negligible and with appropriate identification and evaluation can be considered when interpreting the measurement results of any psychophysiological variable and further diagnosis. Further on, dissertation describes two preliminary experiments (Chapters 3.4 and 3.5), based on which we have developed guidelines for the preparation of the protocol of psychophysiological measurement. In the first experiment we observed the effects of successive measurements of blood pressure using a home blood pressure monitor on the psychophysiology of the observed person. We performed five consecutive blood pressure measurements (i.e. disturbances), and observed changes in psychophysiology (i.e. blood pressure, skin conductance and other physiological variables). We confirmed that the highest blood pressure value is measured at the first disturbance, i.e. the first measurement by home blood pressure monitor, while the real value is closest to the third consecutive measurement. The mean difference between them was +2.1 mmHg for the systolic and +2.8 mmHg for the diastolic pressure. On average, the amplitude is decreasing until the third measurement, and then begins to rise or fluctuate again. It then depends on the number of previous disturbances. Therefore, any possible correction of the final variable should be carried out irrespective of the time elapsed since the start of the measurement, but according to the number of occurrence of the disturbances prior. The relaxation time of psychophysiological variables depends on the level of amplitude of the initial change. If the change was high, the physiological variable will more rapidly decrease to the baseline level as if would when low. In the second experiment, we focused on various forms of measuring methods for measuring psychophysiological variables. We ranged the selected measuring instruments into three categories of measurement methods; non-intrusive measuring methods have been defined as measuring methods in which the measured person is unaware that he/she is being measured / observed. Less-intrusive measuring methods represent methods that are disturbing at the beginning of the measurement and the measured person is aware of, but gets habituated over time and then forgets them. Intrusive measurement methods were defined as methods in which the measured person is very aware of being measured / observed. An experiment was performed to determine the influence of the intrusiveness of the used measurement methods in relation to the changes in the psychophysiology of the measured person and his/her perception of the measurement situation. The results showed that during the measurement process, the measured persons are most agitated by the attachment of measurement instruments and the speech of experimenter. These events trigger the highest reactions of skin conductance response, while the level of skin conductance is increased during questioning. Intrusiveness of the measuring instrument also depends on the number of other instruments used or simultaneously attached to the measured person. From these experiments we can deduct that when measuring physiological variables, it is necessary to use as few measuring instruments as possible, preferably only one which is minimally intrusive, the measurement experimenter must not speak much, preferably at all or it is not even present in the room, and all the questionnaires should be administered after the measurement of physiological variables. Regarding the personality types, we found that less acceptable and more introvert people are more measurement anxious, and therefore the consideration of the above limitations on these persons is more influential. On the basis of the above findings, a final measurement protocol was prepared which included only three blood pressure measurements (disturbances), measurement of the influence of disturbance on the skin conductance. Psychological questionnaires for measuring personal characteristics and self-assessment scale were placed at the end of physiological measurements. Similar to the first two experiments the results of this experiment indicated that the most burdensome events in the process of measurement were the speaking of the experimenter and the beginning of solving psychological tests. People who were more agitated during the measurement were also more agitated by an individual event within the measurement process, especially for less confident individuals who responded more strongly to certain disturbances within the measurement process. Data analysis also showed that the measured persons were more measurement anxious when the measurement was carried out by a male person. On average, the results of this experiment indicate lower response rates for all measured persons. This can be attributed to the random selection of people as such or to the actually less burdensome protocol of measurement. On the basis of all performed measurements we also evaluated the measurement uncertainties of classical psychophysiological measurements and prepared a proposal to reduce the measurement uncertainty of psychophysical measurements, which is at the same time the basis for the preparation of a nonintrusive measurement protocol of psychophysiological measurements. We conclude that non-invasive blood pressure measurement with home blood pressure monitor represents an intrusive disturbance that increases the activity of skin conductance by less than 1 μS and affects the blood pressure value. On average, the systolic and diastolic blood pressure values increased by less than 15 mmHg at the first disorder, with a measurement uncertainty of under 10 mmHg. A strong increase of physiological changes was characteristic of less confident and more introvert people. A detailed consideration of these findings on a larger number of measured persons presents future challenges in the field of metrology of psychophysiological measurements.

Keywords:psychophysiological measurements, blood pressure, skin conductance, measurement uncertainty, measurement anxiety, protocol

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