Signals are also passed from one neurone to another even tough they do not touch. Between nerve endings there are small gaps called synapses, signals can be passed through synapses because when an electrical impulse reaches a synapse, chemicals called transmitter substances are released from the membrane of one nerve ending and travel across to special receptor sites on the membrane of the next nerve ending, triggering off another nerve impulse. Signals however are not always passed across the synapses.
Planning: in this experiment I will be investigating how the different factors affect the time of reaction. I will be depriving my fellow students of there sight to see how it affects there reaction time. In this experiment I decided I will drop a 50cm ruler 10cm above everyone’s right hand and see how long it takes them to catch it. The students will all try it with their sight and without their sight so I can compare the results and see how much sight affects the rate of reaction. I will further my experiment by comparing the girls and boys results to see if gender affects the rate of a persons reaction. In total I will use 5 girls and 5 boys I will also compare those people who are left of right handed.
Aim: To investigate the effect of depriving people from their senses and how this affects there reaction rate.
Factors and fair test: If I am going to make this a fair test, then I will have to control these other factors like I mentioned below:
The main factors which will need to be considered whilst doing the experiment are:
- The sex of the student. Whether they are a girl or boy will affect there rate of reaction so I will be using the same amount of boys and girls. I will be investigating this further.
- There sight will affect the rate of reaction for example they can see the ruler they will be more likely to catch it. This is another factor I will be testing.
- The distance between their hand and ruler will affect the rate of reaction as they will be able to catch it quicker if it was closer to ensure its affair experiment I will be measuring 10cm above the hand each time I do the experiment so the distance will be kept constant.
- Weather they use there left or right hand will affect there rate of reaction as if there usually left handed it will be more difficult for them to catch it with their right hand.
- The hearing of a student can affect the rate of reaction because if they were to here someone shouts before the ruler was dropped they would prepare themselves for it.
- The age of the person will also affect there reaction rate as a younger person’s reflexes tend to be quicker.
- The ethnic background can also affect the rate of a person’s reaction as a person from Jamaica will tend to be faster as they all tend to have longer legs. In my class there are Asians and whites so out of 10 boys and girls I will be doing half will be white and the other Asians.
- The health of the person will also affect there reaction rate as if there in good health they will be quicker. Everyone I am experimenting is in decent health.
- Also weather they had practice or nor because in theory practice makes perfect in this case your reflexes would quicker because they’d be prepared.
Hypothesis: The nervous system collects information about changes inside or outside the body, decides how the body should respond and controls that response. Information is collected by receptor cells that are usually grouped together in sense organs, also known as receptors. Each type of receptor is sensitive to a different kind of change or stimulus. There are five different sense organs. The sense organs which will be used when the students have to catch the ruler are sight and touch. In the first investigation between the differences in seeing the ruler and not I believe everyone will be quicker at catching the ruler when they can see this is because they will be using two senses and will react quicker then if they are just depending on one sense. For example if they can only feel the ruler and not see the ruler the signals to the brain will be sent to the brain as soon as they feel the ruler slip through there fingers which means by the signal return and the hand moves the ruler will have slipped a little more. Therefore if one was able to see they would be quicker in gripping the ruler as the signals would be faster and the senses would work faster.
The difference between girls and boys reaction time in my opinion will vary in how athletic they are, i.e. I don’t think the boys or the girls will be faster then each other. I believe the result for this will be equal. Also the last investigation for left and right handed people I believe as in our experiment everyone will be using there right hand so the left handed people will be slower whilst being blindfolded and seeing the ruler this is because they are so used to sending signals from there left hand this means the right side of there brain is used to receiving the signals not the left side which will be the case when they use there right hand.
Apparatus:
- 50 cm ruler
- 30cm ruler
- 10 students (5 boys and 5 girls)
- a scarf to cover the eyes
Method: in order to do the following experiment I will be following this procedure:
- Collect the apparatus.
- I will have to measure 10cm from each persons hand and drop the ruler between there hand when they can see as soon as they catch the ruler I will record the measurement they caught it at.
- For each person I will do this 10 times so I have varied results which will be more accurate.
- I will then blindfold each person and repeat the experiment. Each person will be tested 10 times.
- After I have recorded the results I will test those who are originally left handed to see if there is a big difference.
- The results will be recorded in a table.
Preliminary Work: Prior to this experiment I did an experiment to help with a prediction and also to help indicate a number and range for the main experiment. The results from this experiment had many errors occur due to humanly errors. Whilst doing the experiment we didn’t measure the 10cm above the hand accurately. This caused all are results to be inaccurate also we decided we needed to be more careful when measuring the 10cm above people hand because they kept moving there hand as the ruler went up. Also we only when we did out preliminary experiment we only did the experiment 5times. This didn’t give us a good range of results and caused the whole experiment to weaken. We noticed no adequate conclusion could be backed up with sufficient evidence as a suitable graph could not be formed.
We also tried different measurements from the hand and came to the conclusion 10cm would be adequate. From the preliminary experiments we decided to do the experiment 10times so we could monitor the investigation closely. So in our real experiment we decided on 10cm from the hand and we would repeat it 10times.
The results below show the preliminary results as you can see they are inaccurate. Doing this preliminary experiment helped us improve our real experiment greatly.
Safety: To ensure safety, I will keep all stools tucked in and also ensure everyone holds their arm out so if the ruler is to fall back it will not hurt them.
Obtaining your evidence: Whilst we were doing the experiment I was fortunate as I was able to follow the method.
Experiment one: full sight.
Experiment two: blindfolded
Key: - Boys
To make my results accurate I will find out the mean of each person.
With sight:
Without sight:
The mean of the girls and Boys:
In total there was one person who was left handed that was Sadia so we did the experiment again to see if it mattered weather she used her left or right hand. The results are below:
Considering the results:
Conclusion: The graphs above show the mean of the students catching the ruler where they could see and when they were blindfolded. From the results you can see the mean was higher when they were blindfolded. This is mainly because when they could see, they were using two senses whereas when they were blindfolded they were depending on one sense. My conclusion was correct. However there seems to be a mixed result as for some the mean seems to be higher when they could see, but looking at the results everyone seemed to get better with practice.
There was one girl who was originally left handed but she did the experiment with her right hand for the sake of the experiment. We asked her to do the experiment with her right hand to see if it made a difference in her reaction rate. The graph below shows she was much quicker with her left hand then her right this is because they are so used to sending signals from there left hand this means the right side of there brain is used to receiving the signals not the left side which will be the case when they use there right hand.
The last graph shows the mean between the girls and the boys and it shows the boys were much quicker in collecting the ruler then the girls. This is probably due to the fact that the boys are more athletic then the girls. Overall the conclusion backs up my initial prediction.
Evaluation: There were not many out of the ordinary results in the second experiment, but some were not as close to the line as others. There were anomalies which were cancelled out and repeated as they didn’t fit in with the pattern. This may have been caused by human errors. The results I collected overall weren’t entirely the ones I expected, I wouldn’t say they were 100% accurate as the ones which people are blindfolded they are meant to do worse then which they can see. I would say the humanly errors were:
- For example if the student wasn’t able to catch the ruler and it slipped through there hands we ignored it and repeated the experiment again.
- Also with the theory of practise makes perfect we didn’t entirely follow it through as some people did half of the experiment.
- When we were measuring the 10cm above the persons hand the measurement were unclear as they were not always accurate because the tip of the ruler didn’t always touch the hand.
Whilst doing the experiment it was difficult to keep 10cm from the hand and drop the ruler between their thumb and index finger. There were many attempts before the actual ruler went through. Looking through the results I find them sufficient enough to back my conclusion up as they do show the general pattern I was looking out for.
If I was to do the experiment again I would find a more accurate way of measuring as at times the experiment was quite confusing. I would also want to test something other then a ruler. I would also change more variables but due to the lack of time this wasn’t possible. The results however were taken 10times and a mean was found which seemed adequate as it was overlooked by large values.
The results we took aren’t too narrow as we took results from a wide spread and verity of people but if I was to do the experiment I would test people of different age groups as this time we only tested students age 15-16. They attend to have quicker reflexes as they are fitter then old peoples. I believe if we were to do older people they would take longer to catch the ruler.
These results can be used for a graph as they generally follow a trend and show the more senses you use the quicker you are.
Further work: To extend this experiment it could be repeated exactly as before, by other variables being changed, or these variables being extended i.e. like the blindfolded student being able to use his ears. The ruler could be let go and someone could shout now.
Other variables in the experiment could be changed for example we could test to find out which part of the skin contains the most touch receptors, or we could see which part of tongue is able to taste different flavours as these are other senses which can be investigated. Also with this experiment the distance between the hand and the ruler could be varied as distance can affect your reflex if you are able to use you sight.
