# NTNUJAVA Virtual Physics LaboratoryEnjoy the fun of physics with simulations! Backup site http://enjoy.phy.ntnu.edu.tw/ntnujava/

## Easy Java Simulations (2001- ) => kinematics => Topic started by: ahmedelshfie on June 28, 2010, 06:56:59 pm

 Title: Reaction time measurement Post by: ahmedelshfie on June 28, 2010, 06:56:59 pm This following applet is Reaction time measurement (EJS version)Created by prof Hwang Modified by Ahmedoriginal project Reaction time measurement (http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=387.0) Title: Re: Reaction time measurement Post by: ahmedelshfie on June 29, 2010, 09:08:42 am Reaction time (RT) is the elapsed time between the presentation of a sensory stimulus and the subsequent behavioral response. RT is often used in experimental psychology to measure the duration of mental operations, an area of research known as mental chronometry. In psychometric psychology it is considered to be an index of speed of processing.[1]  That 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. The behavioral response is typically a button press but can also be an eye movement, a vocal response, or some other observable behavior.RT is fastest when there is only one possible response (simple reaction time) and becomes slower as additional response options are added (choice reaction time). According to Hick's law, choice reaction time increases in proportion to the logarithm of the number of response alternatives. The law is usually expressed by the formula RT = a + blog2(n + 1), where a and b are constants representing the intercept and slope of the function, and n is the number of alternatives.Reaction time is quickest for young adults and gradually slows down with age. It can be improved with practice, up to a point, and it declines under conditions of fatigue and distractions. Title: Re: Reaction time measurement Post by: ahmedelshfie on June 29, 2010, 09:09:56 am HistoryThe Persian scientist, Abū Rayhān al-Bīrūnī  was the first person to describe the concept of reaction time:Not only is every sensation attended this by a corresponding change localized in the sense-organ, which demands a certain time, but also, between the stimulation of the organ and consciousness of the perception an interval of time must elapse, corresponding to the transmission of stimulus for some distance along the nerves.The first scientist to measure reaction time in the laboratory was Franciscus Donders. Donders found that simple reaction time is shorter than recognition reaction time, and that choice reaction time is longer than both.Donders also devised a subtraction method to analyze the time it took for mental operations to take place.By subtracting simple reaction time from choice reaction time, for example, it is possible to calculate how much time is needed to make the connection. Title: Re: Reaction time measurement Post by: ahmedelshfie on June 29, 2010, 09:11:29 am MeasurementThere are four basic means of measuring RT given different operational conditions during which a subject is to provide a desired response:Simple reaction time is the time required for an observer to respond to the presence of a stimulus. For example, a subject might be asked to press a button as soon as a light or sound appears. Mean RT for college-age individuals is about 160 milliseconds to detect an auditory stimulus, and approximately 190 milliseconds to detect visual stimulus.Go/No-Go reaction time tasks require 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.Choice reaction time tasks require distinct responses for each possible class of 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. The Jensen Box is an example of an instrument designed to measure choice reaction time.Discrimination reaction time involves around Natwain comparing pairs of simultaneously presented visual displays and then pressing one of two buttons according to which display appears brighter, longer, heavier, or greater in magnitude on some dimension of interest.Due to momentary attentional lapses, there is a considerable amount of random variability in an individual's reaction time. To control for this, researchers typically require a subject to perform multiple trials, which are then averaged to provide a more reliable measure.Data from  http://en.wikipedia.org/wiki/Reaction_time Title: Re: Reaction time measurement Post by: ahmedelshfie on September 26, 2010, 01:20:02 am Original applet of Reaction time measurement design by prof HwangURL applet Reaction time measurement (http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=137.0)