Physiological and psychophysical methods


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Physiological and psychophysical methods

  1. 1. Physiological and psychophysiological methods for assessment of efficiency and fatigue Efficiency is the ability of the person toperform work with certain capacity for certain period of time (working shift). Efficiency could be physical and neuropsychological.
  2. 2. Fatigue is a physiological condition, condition expressed in temporary reduction ofhuman’s capacity to perform physical, mental or psychological activity. Fatigue is an important protective phenomenon of organism.Fatigue could be expressed as a feeling of lack of energy and motivation. It could be physical, mental or both.
  3. 3. Several groups of methods are available for psychophysiological assessment of efficiency and fatigue Assessment of the concentration of attention Such studies can be performed with the help of different tests in the form of characters (letters,shapes) or computer programs. The investigated person have to struck a sign or combination of characters in a consistent view of lines.
  4. 4. A test of this kind is the one of Anfifmov, using letters. The test consists of 40 lines with 40 characters for line, situated in different sequence. The test should be performed for 3 minutes. The results are reported as the number of signscrossed correctly, the omited ones or redundand ones.The attention’s concentration is evaluated by the rate of the productivity factor and by the factor of accuracy, using special formulas.
  5. 5. Schultze sample provides information about the volume, flexibility and allocation of the attention.In the test are used tables with 49 enumerated squares– from 1 to 25 are colored in black, and from 1 to 24 – colored in red, located in random order. Theinvestigated person is asked to indicate and name theblack and red squares consistently – the black ones in ascending order (from 1 to 25), and the red ones – in descending order (from 24 to 1).The test is performed for 2-3 min. and the number of errors and the time for discovery of numbers arereported, which increase with appearance of fatigue.
  6. 6. Determination of the volume, accuracy and speed of received informationThe test below (using tables, consisting of the rings of Landolt or other symbols) isperformed to evaluate the vision, as well as the speed and accuracy when processing visual information. The ring of Landolt has a hole opening indifferent clockwise. The test consists of 32 rows by 32 characters.
  7. 7. Should be conducted for 2-3 min. and is used to measure the speed recorded by the ring reading. The results are converted into bits per second.As a result of the fatigue onset the speed of revising the information have been reduced and the number of errors increased.
  8. 8. The test enables to assess rescuers, firefighters, soldiers, policeman and other demanding occupations, requiring control and, for example, could be performed before and after training process at polygon.The results correlate particularly withthe results of assessment of prolonged attention concentricity.
  9. 9. Tremometry A method revealed for assessment of accuracy and coordination ofmovements. The test is conducted with a special apparatus called tremometer supplied with coordination curves, on a sheet of paper with drawn coordinationcurve, or with special computer programs. The test allows to investigate static and dynamic tremor.
  10. 10. To examine the static tremor the person puts aneedle in a metal hole with diameter of 2 mm for 30 sec with an elbow stretched and tries not to touch the walls of the hole. In examination of dynamic tremor the tested person pushes the needle in the canal of the apparatus (or the pen is passed between the gutters of the curve) as quickly as possiblewithout touching the walls. The hand should not be supported. The execution time and the number of wall touches are taken into account in the test.
  11. 11. Evaluation of visual function and fatigueAn important indicator of visual function is the stability of clear vision. For this evaluation is used the stereoscopiccube of Korotkov. Clear vision is when theexamined person sees 1 cube at the top row and 2 cubes at the bottom. The illusoryreversal of the image – a view of 2 cubes at the top and 1 cube at the bottom is called unclear vision.
  12. 12. The test is performed for 3 minutes and the person reports the times of change of clear and unclear vision.The stability of clear vision is given by a formula. The stability of clear vision is LOW when the result is under 58%.
  13. 13. Mental chronometryEvaluation of the latent period of senso- motor reactionMental chronometry is the use of response time in perceptual-motor tasks to infer thecontent, duration, and temporal sequencing of cognitive operations. Mental chronometry is studied using the measurements of reaction time (RT).
  14. 14. Reaction time is the elapsed time betweenthe presentation of a sensory stimulus and the subsequent behavioral response. In psychometric psychology it is considered to be an index of speed of processing. That processing is, it indicates how fast the thinker can execute the mental operations needed by the task at hand. In turn, speed of processing is considered an index of processing efficiency. efficiency
  15. 15. The behavioral response is typically a buttonpress but can also be an eye movement, a vocal response, or some other observable behavior. Response time is the sum of reaction time plus movement time. Simple reaction time is the time required for an observer to respond to the presence of a stimulus. In simple reaction time experiments there is only one stimulus and one response.For example, a subject might be asked to press a button as soon as a light or sound appears.
  16. 16. Mean RT for college-age individuals is about 160 ms to detect an auditory stimulus, andapproximately 190 ms to detect visual stimulus. Recognition or Go/No-Go reaction time tasksrequire that the subject press a button when one stimulus type appears and withhold a response when another stimulus type appears.For example, the subject may have to press the button when a green light appears and not respond when a blue light appears.
  17. 17. In choice reaction time (CRT) tasks there are multiple stimuli and multiple responses and distinct responses are required for eachpossible class of stimuli. The reaction should correspond to the correct stimulus. For example, the subject might be asked to press one button if a red light appears and a different button if a yellow light appears.Performers may receive stimuli by the eyes, the ears and kinestetic sense.
  18. 18. Discrimination reaction time involves comparing pairs of simultaneously presented visual displays and then pressing one of two buttons according to which display appearsbrighter, longer, heavier, or greater in magnitude on some dimension of interest. Reaction time could be influenced by many factors, such as age, gender, physical fitness, personal type, whether the stimulus is auditory or visual etc. The onset of fatigue extends the reaction time.