1. REACTION TIME www.zimbio.com

2. Reaction Time
Reaction time is the time taken to respond to a stimuli (a starters gun, green light, moving ball etc). Being able to respond quickly is very important in many sports.
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3. RESPONSE TIME = REACTION TIME + MOVEMENT TIME
Reaction Time is also associated with Movement Time and Response Time.
Movement time is the amount of time it takes the body to complete the movement.
Response Time is the total reaction time added to the movement time
RESPONSE TIME = REACTION TIME + MOVEMENT TIME

4. Types of Reaction Time
Simple reaction time is a simple response to a single stimulus. Eg press the button when you see the light. Choice Reaction time is where several stimuli are presented at once but only one is selected. Eg. A colour will appear on screen, press the coloured button that corresponds to the colour on screen. Red, blue, or yellow choices. The more choices a person has, the more information needs processing and the slower the reaction time (a larger or longer reaction time).

5. Hick’s Law (1952)
States that there is a relationship between the number of stimulus presented and reaction time. As the number of stimulus response alternatives increases so does the time taken to react. Hick’s Law maintains that there is a linear relationship between reaction time (or time taken to make a decision) and the amount of information to be processed.
Reference: VCE Physical Education, book 1, 3rd Edition, Damien Davis, Tom Kimmet, David Ackerly, Andrew McAree & Geoff Hosford, Macmillan Education Australia, P219

6. Psychological Refractory Period (PRP)
When a second stimuli is presented after the first one (eg. A fake pass in basketball) the response time is longer. The brain has to “unload” the movement program for the first response and then re-load a new program for the correct response. This is called the Psychological Refractory Period (PRP). For example a defender in basketball may fall for a fake pass and start their movement to defend the ‘pass’. The brain needs to stop that movement, load up the correct movement and then get the body to perform it…this can take up to 500 ms (.5 of a second) which gives the attacker more than enough time to move in the other direction or take a shot at the basket.

7. Factors that affect Reaction Time
AGE
Generally speaking, children under 10 and adults over 60 have a slower reaction time than the remaining population. Generally speaking, reaction time begins to increase after the mid twenties
GENDER
Studies generally show that males have a shorter reaction time than females but the increase because of age is slower in females.
INTENSITY OF STIMULUS
As the intensity of the stimulus increases, there is a corresponding decrease in reaction time. A performer will take a shorter time to react to a bright coloured, noisy or larger stimulus for example.
THE PROBABILITY OF A STIMULUS OCCURRING
Anticipation is the skill related to predicting when a stimulus will occur. This effectively reduces reaction time as you can be pre-prepared for it. When stimuli are unpredictable, your reaction time will be longer meaning performers should vary their game plan so that opponents cannot predict their next move. In tennis for example, a tennis player will anticipate to which side the server will serve the ball in order to initiate their reaction earlier.
THE PRESENCE OR ABSENCE OF WARNING SIGNALS
You can reduce reaction time by recognising the signals that indicate a movement is about to take place for example the ‘on your marks, set, go’ commands for a sprint race or a team member signalling that a particular tactic will be employed at a certain time.
SIGNAL DETECTION
An Athletes ability to determine whether or not a cue or stimulus is present will impact their ability to initiate a response. Thus if the sense organs are unable to detect a stimulus or if the stimulus is not very strong, the time it takes for the brain to receive information from the senses to process the information will be impacted.
PREVIOUS EXPERIENCE
Past experience will undoubtedly enable a performer to pick up appropriate cues more quickly and easily, thus reducing reaction time. A coach may be useful in giving a performer direction so that they can plan ahead and therefore reduce reaction time. A consistent response by an opponent may be picked up by a coach so that you can deal with it differently next time.
SELECTIVE ATTENTION
Your senses may detect the stimuli but you may be unaware of them. The ability to filter out irrelevant background information (eg background nise) and attend to only the relevant stimuli is called Selective attention. It effectively reduces the number of incoming stimuli that need to be processed and so reduces processing time (Amezdroz et al, 2010, p 46).

8. Ways to improve reaction time
Practice – The more often a stimuli is responded to the shorter the reaction time becomes. Mental Rehearsal – going over correct responses in your mind eg.a soccer goalie visualising saving penalty kicks by diving to her left. Concentration – learning to ignore irrelevant signals eg. A swimmer focusses on the sound of the starters gun and blocks out all the crowd noise. Anticipation – picking up cues in the environment that let you know a movement is coming and moving before it occurs eg. Seeing a tennis player throw the ball a certain way and identifying they are going to serve wide so you begin moving before the ball is hit.