reaction times
Biology 104
Reaction Times
Objectives:
1. Formulate and test hypotheses regarding reaction times.
Introduction:
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. Many factors have been shown to affect reaction times, including age, gender, physical fitness, fatigue, distraction, alcohol, personality type, and whether the stimulus is auditory or visual.
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
Sensory neurons convert a stimulus into an electro-chemical signal, which flows the length of the sensory neuron(s), then through a neuron or neurons of the central nervous system, and then through the length of the motor neuron(s). Generally, motor neurons will cause a muscle to contract or a gland to secrete a substance. Reactions that involve only the receptor, the spinal cord, and the effector, are faster than those which involve processing in the brain. Reactions which only travel to, through, and from the spinal cord are often called spinal reflexes or cordmediated reflexes; withdrawing one’s hand from a hot stove is an example of such a reflex.
In ‘simple reaction time’ experiments, there is only one stimulus and one response. Catching a dropped stick, or hitting a button when a light changes are examples.
In ‘recognition reaction time’ experiments, there are symbols to respond to and symbols to be ignored. There is still only one correct stimulus and one response. An example would be catching a dropped stick with a word cue, while having to ignore other spoken words
Reaction Times
Objectives:
1. Formulate and test hypotheses regarding reaction times.
Introduction:
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. Many factors have been shown to affect reaction times, including age, gender, physical fitness, fatigue, distraction, alcohol, personality type, and whether the stimulus is auditory or visual.
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
Sensory neurons convert a stimulus into an electro-chemical signal, which flows the length of the sensory neuron(s), then through a neuron or neurons of the central nervous system, and then through the length of the motor neuron(s). Generally, motor neurons will cause a muscle to contract or a gland to secrete a substance. Reactions that involve only the receptor, the spinal cord, and the effector, are faster than those which involve processing in the brain. Reactions which only travel to, through, and from the spinal cord are often called spinal reflexes or cordmediated reflexes; withdrawing one’s hand from a hot stove is an example of such a reflex.
In ‘simple reaction time’ experiments, there is only one stimulus and one response. Catching a dropped stick, or hitting a button when a light changes are examples.
In ‘recognition reaction time’ experiments, there are symbols to respond to and symbols to be ignored. There is still only one correct stimulus and one response. An example would be catching a dropped stick with a word cue, while having to ignore other spoken words
Bibliography: Kosinski, Robert J. 2005. A Literature Review of Reaction Time. Accessed March 17, 2005. Marieb, Elaine N., Exercise 22 Human Reflex Physiology, Activity 9: Testing Reaction Time for Basic and Acquired Reflexes, pp. 232-233, Human Anatomy and Physiology Laboratory Manual (Cat Version), 2003,7th Ed.- Update, Benjamin Cummings, San Francisco, California. 4