SHMD219 HUMAN MOVEMENT STUDIES

1. SHMD219 HUMAN MOVEMENT STUDIES Producing Actions TIME FACTORS THAT INFLUENCE PRODUCING ACTIONS

2. Time Factors that Influence Producing Actions • The brain strives to become efficient and effective in perceiving movement situations and producing actions. • Three timing factors have an influence on information processing. • The time needed to process information • The potential for a psychological refractory period or delay in the time for processing information. • The cognitive capacity to anticipate what will happen in a movement situation.

3. 1.Time as a Feature of Information Processing • So many skills involved in games require that you time your actions correctly. • There are several variables that affect the timing of movement performance, these include; • Reaction Time • Movement Time • Internal and External timing considerations.

4. 1.Time as a Feature of Information Processing Reaction Time 1.Choice reaction time- the more choices the longer the processing time. It is slower because of the time it takes to process alternatives. 2.Complexity of the response-the more complex the movement patterns the longer time it will take to organize the programs, schemas and motor commands you need to activate the muscles. 3.The duration of the response- the amount of time it will take to perform the movement influences the amount of time required to organise the relationship of the programme-schema-command. 4.Type of stimulus-yourreaction to kinaesthetic stimuli is the fastest -your reaction to auditory stimuli will be faster by about 50 milliseconds than your reaction to visual stimuli. - reaction to tactile stimuli is somewhere in between auditory and visual stimuli

5. 1.Time as a Feature of Information Processing Movement Time • It is the amount of time it takes you to complete the movement pattern. • It is measured from the first sign of action until completion of the action. • Your reaction time + your movement time = your response time. • If a movement is to be performed slowly reaction time will be slower than when it has to be performed quickly.

6. 1.Time as a Feature of Information Processing Internal timing • Defined as the coordination among the various body parts during the performance of a movement. • When performing closed skills (skills performed in relatively stable and unchanging environments) you focus on your form. • E.g. The coordination need in the high jump-each of the body parts must move in a very precise relationship to each other.

7. 1.Time as a Feature of Information Processing External Timing • It is the coordination of your movement patterns to the dynamics of your environment. • The natural dimensions of the environment such as the size of the court. • The artificial dimensions of the environment such as the weight of the piece of the equipment. • The human dimensions of the environment such as the opponent’s style of defence. • External timing is critical to success to in performing open skills

8. 2. The Psychological Refractory Period • In many movement situations there is continuous change. • This is called a dynamic environment. • This means your are continuously perceiving and your are continuously producing actions. • Your system has a limit on how much information it can process and how quickly. • This limit is evident when you experience a delay in how quickly you can respond to two closely placed stimuli, and • How quickly you can produce two separate actions.

9. 2. The Psychological Refractory Period (PRP) • It both cases the delay is described as the psychological refractory period. • Which is the delay in your system’s capacity to process separate pieces of information.

10. 2. The Psychological Refractory Period Delays in Responding to stimulus • You can experience a delay in your ability to respond in a situation when two stimuli are presented closely together. • For example: in basketball when an opponent is dribbling the ball toward you, then fakes a move to the left before going to the right, • There is an amount of time between the fake and the following action that is called the Inter stimulus interval (ISI).

11. 2. The Psychological Refractory Period Delays in Responding to stimulus Interstimulus interval (ISI). • If the ISI is long enough, you will have no difficulty in responding to the first one and second one successfully. • If this interval is “just right” you will experience a delay in processing the second stimulus, which means you will not be able to perform a response to it at the correct time

12. 2. The Psychological Refractory Period Delays in Responding to stimulus Interstimulus interval (ISI). • You brain can only organise and initiate one action at a time. • You literally must wait until the first response is completed. • That is you cant plan a second response before you finish planning and programming the first response. • You can see your opponent going to the right, but you can not do anything about it immediately . • You are “stuck” moving in the direction of the fake and must wait until your system clears that move before planning and executing another move.

13. 2. The Psychological Refractory Period Delays in Producing Actions • You can not perform 2 separate actions at the same time. • When a motor programme plus a schema is joined with a motor command and that command is issued ,it can be regarded as a “chunk” or a burst of activity that exclusively occupies several hundred milliseconds until the next one can be generated. • This means that although information is provided continuously, responses are generated in units. • When teaching complex skills they have to be taught in parts. • If you want to teach a child to catch a ball while running, she will run, then stop to try and catch the ball, then run again: three separate actions separated by the psychological refractory period.

14. 2. The Psychological Refractory Period Delays in Producing Actions (cont…) • But if you first make sure she knows how to catch, then slow down the run and the speed of the ball as it comes to her, • You will find that the child’s system begins to chunk running and catching into a combined motor programme with a single schema that can be processed as a single action.

15. 3.Anticipation • One of the most effective ways of dealing with delays in planning and programming movements is through the process of anticipation. • Anticipation is your ability to predict an event, which means you can prepare for it by processing information in advance. • There are two types of anticipation: • Event anticipation (what will happen) • Temporal anticipation (when will it happen)

16. 3.Anticipation Event Anticipation • Your cognitive understanding of a situation is the foundation of your ability to anticipate events. • Based on your perception of selected spatial cues you may be able to deduce what will happen next in the situation. • Elite athletes spend time studying their opponents. • They are building their knowledge about their opponents’ preferences and habits, so they will be able to predict what the actions their opponents will take in different kinds of situations. • Once the situation has been anticipated, the necessary program, schema and schema can be assembled. • This means that once the predicted stimuli occurs, all that is left is the activation of the command. • This is referred to as pre-programming movements. • Activating a pre-programmed movement requires a fraction of the time needed for the full processing of a response to unanticipated stimuli.

17. 3.Anticipation (cont..) Temporal Anticipation • It works together with event anticipation. • If you can predict when something will occur, you can often get into position to execute your pre-programmed response.

18. 3.Anticipation (cont..) Cost of Anticipation • Anticipation is an advantage because it helps reduce the amount of time it takes you to respond to a situation. • It can be a disadvantage if you make a mistake