We are conducting this experiment because we wanted to research the affect of music on plant growth. The theory is that music will help plants, or in this case petunias, to grow faster/bigger. We are using three different types of music and are studying which has the greatest affect on the growth of the petunias.
This would mean that the cause construct of the theory is music, with the effect construct being plant growth. So our experimental hypothesis is: “Type of music has a significant effect on the height of petunias” causing our null hypothesis to be “Type of music does not have a significant effect on the height of petunias.” We are hoping that by carrying out this experiment we will prove one of our hypotheses.
For this experiment we used an independent measures design as plants may well go through growth spurts at different times in their lives like us. So without doing extra research and finding out they grow at a steady pace throughout the whole of their lives, a repeated measures design would be completely unsuitable.
Our independent variable (or IV) was the type of music that we played to the petunias and our dependant variable (or DV) was the height the petunias grew to. To keep the experiment fair and precise we had to try to keep all extraneous (confounding) variables the same. For example, we kept them in the same amount of sunlight, O2, CO2, space, water, music and all at room temperature.
We carried out the procedure like this:
1. We took four equal groups consisting of six young petunias in each and played three groups, three different types of music and had a control group that didn’t hear any music. They were played the music separately for six hours a day, at the same time of day every day for one week.
2. Their heights were measured at the beginning and at the end of the week at the same time and recorded immediately.
3. We then worked out how much each petunia had grown during the week and found averages for each of the groups, including the control group.
Of course, we will also look at the different types of music having different effects on the growth of the petunias as they may well have different outcomes.
We found the average amount the petunias grew over the week from each group to compare the results. They are found here in the table below;
As it is not very easy to compare results in the table I will also convert these results into a graph.
As you can see, groups B and C grew considerably more than groups A and D. Group D was the control group and so heard no music during the week. So out of the three groups that had music played to them, two grew a lot more than the group that did not hear music. Group A grew less than the control group, which does not correlate with the other results and is not what we expected to happen.
The results are a little confusing to look at and compare, as they do not give very conclusive findings. We have two groups that after listening to music grew a significant amount more than the control group, but on the other hand we have a group that listened to music and grew less over the week than the control group.
Based on the majority of findings, we would accept the experimental hypothesis and reject the null hypothesis. As the HA states, “Type of music has a significant effect on the height of petunias” and that is probably why the three different groups listening to three different types of music had such different results. Perhaps groups B and C were very similar types of music and group A was different. If only certain types of music stimulate growth in Petunias then this would explain why the results are so different.
We should have probably used a larger sample as petunias could grow at very different rates individually and that could be why the results are how they are. We could have also carried it out at different times of year as that could explain different growing patterns. Another improvement could have been carrying it out for longer. We should have had a much larger range of music types to thoroughly investigate the effects of different types of music on their growth and used more control groups or investigate beforehand to find the normal average growth over a week to be able to really compare.
If we wanted to carry out further investigation then we could slightly alter the experiment in these ways:
* Try out different sorts of plants
* Research the effects of the volume of music being listened to
* Investigate if similar effects occur in humans e.g. music helping us to learn new skills or understand things better
* We could even investigate whether having the music live or not has an effect!
There are, of course, lots of other ways as well. We could continue this research in these ways to try and deepen our understanding of the subject and find out more about it.