Factors affecting response time.

The idea

Response time is the total interval from the arrival of a stimulus to the completion of the movement it triggers. It combines reaction time, the delay before any muscle activity begins, with movement time, the duration of the action itself. In AQA A-level Physical Education, the factors you must know include the number of stimulus-response choices, stimulus intensity, stimulus predictability, the performer's arousal and attention, age and fitness, and practice or familiarity with the skill. For example, a sprinter reacting to a starting gun has one simple stimulus and a very short response time, whereas a badminton player must read an opponent's racket, decide between several shots and then move, so more choices lengthen the delay. Response time is measured in seconds or milliseconds, and a shorter time is generally better where speed of reaction matters.

What earns the marks

• Response time is the interval from stimulus onset to completion of the resulting movement, so it includes both reaction time and movement time.
• Reaction time is the delay between stimulus presentation and the first muscle activity; movement time is the duration of the movement after that.
• Increasing the number of stimulus-response alternatives increases response time, which is the basis of Hick's law.
• Greater stimulus intensity, such as a louder gun or brighter light, can shorten reaction time up to a point.
• A predictable stimulus allows the performer to pre-programme the response and react faster than to an unpredictable one.
• Optimal arousal and focused attention improve response time, while very high or very low arousal and distraction slow it.
• Age, fatigue, fitness and the amount of practice or familiarity with the skill all influence how quickly a performer responds.
• Response time is measured in units of time such as seconds or milliseconds, and shorter values indicate faster processing.

Common mistakes and how to put them right

• Treating response time and reaction time as identical.

  Put it right: Response time also includes movement time, so it is longer than reaction time alone.

• Assuming more choices always make a performer faster because they are more alert.

  Put it right: Extra stimulus-response alternatives increase decision time and slow the response.

• Believing arousal always improves response time.

  Put it right: Beyond an optimum, high arousal narrows attention and slows or disrupts the response.

• Ignoring measurement units: response time is recorded in seconds or milliseconds, not in metres or arbitrary scores.

Exam tips

• Define response time precisely before applying it, so you can separate reaction time from movement time in your answer.
• Use a named sporting example, such as a sprinter at the gun or a goalkeeper facing a penalty, to show how a specific factor changes response time.
• When a question asks for factors, give several distinct factors and explain the direction of each effect rather than listing them.
• Link each factor to the underlying processing stage, such as stimulus detection, decision making or response programming, to show understanding.