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REACTION TIME

OVERVIEW

•Definition

•Reaction Time

•Motion Time

Definition

Reaction time is a measure of how quickly an organism can respond to a particular stimulus. Reaction time has been widely studied, as its practical implications may be of great consequence, e.g. a slower than normal reaction time while driving can have grave results. The model for information flow within an organism can be represented in this way:

Stimulus Receptor Integrator Effector Response

More specifically, in vertebrates, information flow can be represented in this way:

Stimulus Sensory Neuron Spinal Cord or Brain

Motor Neuron Response

(Kosinski, Robert J. 2005)

csm.jsm.edu

Definition• The time passing from the appearance of a

proximal stimulus to beginning of an effector action is called Reaction Time

• The additional time to perform an appropriate movement is called Motion or Movement time

Note :REACTION TIME + MOTION TIME = RESPONS TIME

Sciencebuddies.org

Reaction TimeIf person knows that a particular stimulus will occur, is prepared for it, and knows how to react to it, the resulting reaction time is called “Simple Reaction Time”.

The Scientist found about the RT calculation with the variable a and b are empiric constants and variable N is number of choices which means a logarithmic of alternative stimuli and responses.

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Ditulis 2 rumusnya

Under optimal conditions, simple auditory, visual, and tactile reaction times are about 0.2 second. If conditions deteriorate, such as uncertainty about the appearance of signal, reaction slows. And the graph below shows that relation :

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Motion Time• Motion time follows reaction time. Movements may be

simple, such as lifting a finger in response to a stimulus, or quite complex such as swinging a tennis racket.

• Movement time also depends on the distance covered and on the precision required.

• And the formula to get the Motion Time was called Fitts’ law which describe below :

Reaction Time CalculationThe way to calculate the Reaction time is not just using the mathematic calculation. But the scientist around the world try to define the way to calculate the reaction time by modern and simple ways such as software. And here are some ways to calculate the reaction time :

Reaction Time

Reaction Times with a

Word Cue and Word

Association

Simple Reaction

Time Task

Flicker fusion

threshold

Simple Reaction TimeSimple Reaction Time (SRT) is a test which measures simple reaction time through delivery of a known stimulus to a known location to elicit a known response. The only uncertainty is with regard to when the stimulus will occur, by having a variable interval between the trial response and the onset of the stimulus for the next trial. As soon as the participant sees the square on the screen, they must press the button on the press pad.

Reaction Times with a Word Cue• This method will once again calculate reaction time by

calculating the time it takes to catch a dropped ruler, but in this method a final word cue is given, as well, after other words are spoken that should be ignored.

1 and 2. Exactly the same as in Method 1.

3. Determine a particular word as a signal to catch the dropped ruler.

4. Use a variety of words before dropping the ruler; disregard ruler catches on wrong word.

5. Record the number at the subject’s fingertips, i.e. distance the ruler fell through the subject’s fingers,

6. Calculate reaction time in seconds as in #6 above

Reaction Time with Word Association

1 and 2: Exactly the same as in Method 1 and 2.

3. Say a stimulus word as a signal to catch the dropped ruler. Do not predetermine the stimulus word. The subject will catch the ruler with any word as a cue. This time, however, the subject 3 must also respond with a word. Keep a record of catches that do no count because of the lack of a word association.

4. Subject responds with a word and catches the ruler while responding. If unable to make a word association, the catch does not count.

5. Record the number at the subject’s fingertips, i.e. distance the ruler fell through the subject’s fingers.

6. Calculate reaction time in seconds as before.

The flicker fusion thresholdThe flicker fusion threshold (or flicker fusion rate) is a concept in the psychophysics of vision. It is defined as the frequency at which an intermittent light stimulus appears to be completely steady to the average human observer. Flicker fusion threshold is related to persistence of vision. Although flicker can be detected for many waveforms representing time-variant fluctuations of intensity, it is conventionally, and most easily, studied in terms of sinusoidal modulation of intensity

Factor Of Reaction TimeMany factors have been shown to affect reaction times, including :

• age, • gender,• physical fitness,• fatigue, • distraction, • personality type, • whether the stimulus type (auditory or visual)• alcohol,

(Marieb, Elaine N., Exercise 22 Human Reflex Physiology)

STUDY CASEPak ergo, selain sebagai pembawa gerobak sampah, beliau juga seorang supir tembak. Ada tiga jenis mobil yang dia gunakan. Ketiga mobil tersebut memiliki keadaan lingkungan yang berupa kebisingan, temperatur, dan pencahayaan yang berbeda. Seorang Mahasiswa teknik industri ingin meneliti apakah lingkungan fisik berpengaruh terhadap waktu reaksi, Berikut merupakan tabel penelitiannya dalam menghitung waktu reaksi dengan metode Simple reaction time dan choice reaction time :

Tentukan kesimpulan dari hasil tabel diatas!

Faktor Lingkungan FisikWaktu rata-rata Hasil

Waktu Reaksi

Kebisingan

Mobil A (40 dB) 279.3333

Mobil B (70 dB) 499

Mobil C (100dB) 711.6667

Pencahayaan

Mobil A (80 lux) 279.3333

Mobil B (400 lux) 329.3333

Mobil C (900 lux) 384.6667

Temperature

Mobil A (18 celcius) 697.3333

Mobil B (25 celcius) 573

Mobil C (32 celcius) 858

Faktor Lingkungan FisikWaktu rata-rata Hasil

Waktu Reaksi

Kebisingan

Mobil A (40 dB) 463.6667

Mobil B (70 dB) 543.6667

Mobil C (100dB) 543.6667

Pencahayaan

Mobil A (80 lux) 459.5

Mobil B (400 lux) 656.5

Mobil C (900 lux) 866

Temperature

Mobil A (18 celcius) 810

Mobil B (25 celcius) 785

Mobil C (32 celcius) 800

Choice reaction TimeSimple reaction Time

JawabanJadi Kesimpulan dari tabel hasil pengamatan diatas adalah :

1. Faktor kebisingan

Dari kedua tes yaitu SRT dan CRT menunjukkan bahwa kebisingan berpengaruh dalam reaction time, semakin kebisingan meningkat maka waktu reaksi dari operator semakin lambat.

2. Faktor pencahayaan

Dari kedua tes yaitu SRT dan CRT menunjukkan bahwa pencahayaan berpengaruh dalam reaction time, cahaya semakin terang maka waktu reaksi dari operator semakin lambat.

3. Faktor temperatur

Dari kedua tes yaitu SRT dan CRT menunjukkan bahwa temperatur berpengaruh dalam reaction time, semakin suhu ruangan meningkat (diatas suhu normal) maka waktu reaksi dari operator semakin lambat.

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