How stimulants affect the rate of reaction time in humans
Abstract:
The purpose of this study is to show the effect caffeine has on the rate of reaction in humans. From
doing my literature review, a hypothesis was formed. The hypothesis states that those who consume
caffeine will have a higher reaction time in comparison to those who don’t have caffeine. Participants
who consumed caffeine drank a total of 50ml of caffeinated drink. From the data collected, it is evident
that the results match the hypothesis. Results show that participants who consumed caffeine had a
higher reaction time than those who didn’t. The data has been put into a table and a graph, and
anomalies have been highlighted in red. The mean has been calculated from the repeats and both
standard deviation and the T test will be used to measure the accuracy of the results. The calculated
standard deviation result for participants with caffeine was 0.0584 and the t test value was 5.8836674
Rate of reaction and the effect of stimulants was plotted on one graph and the participants results from
each group were also plotted on separate graphs. Throughout the practical, there were strengths and
weaknesses which were overcome by following the contingency plan.
Introduction:
The investigation is about stimulants and how they affect reaction time. How stimulants affect the
speed of reflexes, and how they increase or decrease the speed of electrical impulses travelling around
the body. The stimulant that the investigation will be focussed on is caffeine. Further investigation about
this topic needs to be done as there has been no previous studies and all studies are outdated. The
nervous system is made up of the brain, spine and all the nerves in your body. Our nervous system
sends electrical signals around the body using neurons. (Hirsch, L. 2022) These electrical signals cause
bodily movements. There are different types of neurons which have different functions. Neurons are
long in shape which helps to allow impulses to travel longer distances. Neurons are surrounded by a
myelin sheath which insulates the axon, speeding up the movement of impulses. The function of sensory
neurons is to carry signals from the peripheral region to the CNS. The function of relay neurons is to
carry signals around the CNS, and the function of motor neurons is to carry the signals from the CNS to
the muscles. Neurotransmitters are chemical messengers which carry the signal between neurons.
Stimulants will speed up electrical impulses that travel around the body, which will result in faster
reflexes. Caffeine increases dopamine levels and adrenal glands release adrenaline.
There are three stages to a nervous response:
1. A change in the environment (stimulus)
2. Receptor cells then detect this change
3. A response occurs from the effector which is either a muscle or a gland.
Reflexes are actions that your body does. These actions are involuntary and happen as a response.
Blinking when something comes close to your eyes is a reflex as it happens automatically. Reflexes are
important as they protect your body from harm.
Stages in which a reflex occurs:
1. Stimulus heat from the candle
2. Temperature receptors in the skin detect the heat
, 3. Sensory neurons send nerve impulses to the spinal cord
4. Relay neurons send the impulses across the spinal cord
5. Motor neuron sends the impulse from the CNS to the muscle
6. Effector contracts which cause a response
7. The response is the hand moving quickly away from the flame.
Caffeine is a stimulant that increases the speed of which messages are transferred around the body. This
means that stimulants will increase your reaction time and make you more energetic. Your reaction time
is how quickly you respond to a stimulus.
Aim - To investigate how stimulants (caffeine) affect the rate of reaction time. The reason why this is
being conducted is because over the years there has been an increase in the use of stimulants, and
there is not enough research done on this.
Hypothesis - The rate of reaction time would be higher in participants that consume caffeine compared
to participants who don't consume caffeine. This is because caffeine will speed up electrical impulses
that travel around the body, which will result in faster reflexes. There will be a significant difference in
reaction time between participants who consume caffeine and those who do not consume caffeine.
Null hypothesis – There won’t be a significant difference in reaction time for participants who consume
caffeine, and any change is due to chance.
Variables:
Controlled – age of participants and gender of participants (males) (16-18)
Independent – Effect of caffeine consumed (50ml)
Dependent – distance ruler is dropped from (reaction time)
Controlling the gender and age of participants increased the validity and reliability of the results
as the results were not affected by any external factors. It is known that reaction time
decreases with age so the results would not be very valid and reliable if the participants were
all different age ranges. The same applies for gender as a study was done by the ‘IOSR Journal of
pharmacy’, where 100 medical students (50 boys and 50 girls) were tested on their visual reaction time
using different coloured lights (Dr. Ritesh M. Karia et al, 2023.) From the results obtained, it showed that
‘the boys had less visual reaction time compared to the girls.’ After reviewing this study, it was decided
that gender would be controlled to increase the accuracy of results.
Method:
1. Find participants who consent to taking part in the experiment and ensure they are aged 16-18
2. Separate them into 2 groups: one who will be consuming caffeine and one who won't be
consuming caffeine
3. Measure out caffeinated drinks using a measuring beaker and pour them into cups ensuring
each cup has the same volume of drink.
, 4. Allow the group of participants to consume the caffeinated drink and wait 30 minutes for the
caffeine to kick in
5. Drop the 30cm ruler from above the participant and measure the distance it was caught from
6. Do this for both groups of participants and carry out the test 3 times to calculate the mean.
Ensure that the ruler is dropped from the same height for all participants.
7. Record results in a table and plot a graph
8. Calculate the standard deviation and carry out the T test.
Statistical Methods Included:
Standard deviation:
Σ = sum of x̄ = mean x = value
N = sample size
1. The repeats were used to calculate the mean and any anomalies were not included
2. Each value is subtracted from the mean and then squared
3. The value of that number is then divided by the sample size subtracted by 1
4. The value is then square rooted to give the standard deviation
Unpaired T test:
x̄ = mean n = repeats
S = standard deviation .
1. 2 means are chosen and are subtracted from each other
2. The standard deviation for mean 1 (x̄1) is squared and then divided by the sample size
3. The standard deviation for mean 2 (x̄2) is squared and then divided by the sample size
4. Both values from steps 2 and 3 are added together
5. The values of the mean were divided by the square root of the values calculated from step 4
Abstract:
The purpose of this study is to show the effect caffeine has on the rate of reaction in humans. From
doing my literature review, a hypothesis was formed. The hypothesis states that those who consume
caffeine will have a higher reaction time in comparison to those who don’t have caffeine. Participants
who consumed caffeine drank a total of 50ml of caffeinated drink. From the data collected, it is evident
that the results match the hypothesis. Results show that participants who consumed caffeine had a
higher reaction time than those who didn’t. The data has been put into a table and a graph, and
anomalies have been highlighted in red. The mean has been calculated from the repeats and both
standard deviation and the T test will be used to measure the accuracy of the results. The calculated
standard deviation result for participants with caffeine was 0.0584 and the t test value was 5.8836674
Rate of reaction and the effect of stimulants was plotted on one graph and the participants results from
each group were also plotted on separate graphs. Throughout the practical, there were strengths and
weaknesses which were overcome by following the contingency plan.
Introduction:
The investigation is about stimulants and how they affect reaction time. How stimulants affect the
speed of reflexes, and how they increase or decrease the speed of electrical impulses travelling around
the body. The stimulant that the investigation will be focussed on is caffeine. Further investigation about
this topic needs to be done as there has been no previous studies and all studies are outdated. The
nervous system is made up of the brain, spine and all the nerves in your body. Our nervous system
sends electrical signals around the body using neurons. (Hirsch, L. 2022) These electrical signals cause
bodily movements. There are different types of neurons which have different functions. Neurons are
long in shape which helps to allow impulses to travel longer distances. Neurons are surrounded by a
myelin sheath which insulates the axon, speeding up the movement of impulses. The function of sensory
neurons is to carry signals from the peripheral region to the CNS. The function of relay neurons is to
carry signals around the CNS, and the function of motor neurons is to carry the signals from the CNS to
the muscles. Neurotransmitters are chemical messengers which carry the signal between neurons.
Stimulants will speed up electrical impulses that travel around the body, which will result in faster
reflexes. Caffeine increases dopamine levels and adrenal glands release adrenaline.
There are three stages to a nervous response:
1. A change in the environment (stimulus)
2. Receptor cells then detect this change
3. A response occurs from the effector which is either a muscle or a gland.
Reflexes are actions that your body does. These actions are involuntary and happen as a response.
Blinking when something comes close to your eyes is a reflex as it happens automatically. Reflexes are
important as they protect your body from harm.
Stages in which a reflex occurs:
1. Stimulus heat from the candle
2. Temperature receptors in the skin detect the heat
, 3. Sensory neurons send nerve impulses to the spinal cord
4. Relay neurons send the impulses across the spinal cord
5. Motor neuron sends the impulse from the CNS to the muscle
6. Effector contracts which cause a response
7. The response is the hand moving quickly away from the flame.
Caffeine is a stimulant that increases the speed of which messages are transferred around the body. This
means that stimulants will increase your reaction time and make you more energetic. Your reaction time
is how quickly you respond to a stimulus.
Aim - To investigate how stimulants (caffeine) affect the rate of reaction time. The reason why this is
being conducted is because over the years there has been an increase in the use of stimulants, and
there is not enough research done on this.
Hypothesis - The rate of reaction time would be higher in participants that consume caffeine compared
to participants who don't consume caffeine. This is because caffeine will speed up electrical impulses
that travel around the body, which will result in faster reflexes. There will be a significant difference in
reaction time between participants who consume caffeine and those who do not consume caffeine.
Null hypothesis – There won’t be a significant difference in reaction time for participants who consume
caffeine, and any change is due to chance.
Variables:
Controlled – age of participants and gender of participants (males) (16-18)
Independent – Effect of caffeine consumed (50ml)
Dependent – distance ruler is dropped from (reaction time)
Controlling the gender and age of participants increased the validity and reliability of the results
as the results were not affected by any external factors. It is known that reaction time
decreases with age so the results would not be very valid and reliable if the participants were
all different age ranges. The same applies for gender as a study was done by the ‘IOSR Journal of
pharmacy’, where 100 medical students (50 boys and 50 girls) were tested on their visual reaction time
using different coloured lights (Dr. Ritesh M. Karia et al, 2023.) From the results obtained, it showed that
‘the boys had less visual reaction time compared to the girls.’ After reviewing this study, it was decided
that gender would be controlled to increase the accuracy of results.
Method:
1. Find participants who consent to taking part in the experiment and ensure they are aged 16-18
2. Separate them into 2 groups: one who will be consuming caffeine and one who won't be
consuming caffeine
3. Measure out caffeinated drinks using a measuring beaker and pour them into cups ensuring
each cup has the same volume of drink.
, 4. Allow the group of participants to consume the caffeinated drink and wait 30 minutes for the
caffeine to kick in
5. Drop the 30cm ruler from above the participant and measure the distance it was caught from
6. Do this for both groups of participants and carry out the test 3 times to calculate the mean.
Ensure that the ruler is dropped from the same height for all participants.
7. Record results in a table and plot a graph
8. Calculate the standard deviation and carry out the T test.
Statistical Methods Included:
Standard deviation:
Σ = sum of x̄ = mean x = value
N = sample size
1. The repeats were used to calculate the mean and any anomalies were not included
2. Each value is subtracted from the mean and then squared
3. The value of that number is then divided by the sample size subtracted by 1
4. The value is then square rooted to give the standard deviation
Unpaired T test:
x̄ = mean n = repeats
S = standard deviation .
1. 2 means are chosen and are subtracted from each other
2. The standard deviation for mean 1 (x̄1) is squared and then divided by the sample size
3. The standard deviation for mean 2 (x̄2) is squared and then divided by the sample size
4. Both values from steps 2 and 3 are added together
5. The values of the mean were divided by the square root of the values calculated from step 4
