HR CHOICE Discussion section
Andrei Tolins
A1. The hypothesis was that listening to slower music would decrease the heart rate more than listening to faster music. This hypothesis was not supported by the data collected. Instead that data suggests that the opposite is true, though heart rate values for all trials were very close to one another. The experiment assistant did notice the subject moving his hands as if on a keyboard while listening to one of the pieces. The music used for the experiment was the same piece that the subject had performed years earlier. Very likely this fact affected the data, but it is unclear how.
A2. The first experiment that we did as a group led us to consider the question addressed by this experiment. In that experiment we observed that the heart rate decreases as a subject listened to classical music. The data was a little muddy in that experiment though making reaching a confident conclusion about the results impossible. Though the hypothesis of the second experiment was not supported it does conform to the trend established in the first experiment. With the data collected now from both experiments it is possible to say confidently that a subject listening to classical music will experience a heart rate decrease.
B. The reflex loop studied in the experiment is the same as was studied in the first. The stimulus is classical music at various tempos. This music is detected by hair cells in the ear. These signals are transmitted to an integrating center through an afferent pathway, in this case, the auditory nerve. The Integrating center is the Medulla Oblongata and the efferent pathway is the vagus nerve. The effectors are the auto rhythmic cells in the heart. Since all this activity takes place in the sympathetic division of the PNS, we observe a heart rate decrease.
C1. In this experiment a control was used to help procure the best data possible. Prior to introducing a stimulus the subject lied down on a couch for five minutes to make sure the heart rate change would start from baseline. Additionally, because this experiment required two repetitions, a thirty minute break between repetitions was employed to make very sure that the results of the first trial would have no effect on the results of the second.
D1. If doing this experiment again, the best change to make would be to make sure the musical selections used are completely new to the listener. This way the lab team will not be forced to consider after the fact if an emotional or mechanical resonance toward one specific piece of music might factor in the heart rate response. Additionally doing more trials with more subjects would of course provide better and more reliable data from which to draw conclusions.
D2. A well-funded lab could use continuous heart rate monitoring to observe the heart rate response to the stimulus in real time. It is possible that the heart rate response to music happens very quickly after exposure to a stimulus before self-correcting, in which case without real time monitoring it would be very difficult to see what is going on.
E1. Ultimately, the hypothesis was not supported by the data collected. The measured heart rate was consistently very slightly higher when listening to the slower piece of music. Both trials showed the heart rate decreasing in response to classical music generally, so it seems the findings of the first experiment are still valid. The reflex loop studied in this experiment is the exact same loop as in the original heart rate experiment. The control used in this experiment was the same as in all the previous experiments, with the exception that this time there was included a 30 minute break between the two trials. This difference is necessary because the other experiments did not include two trials whereas this one did. The major problem with this experiment is that the subject had a connection with one of the pieces of music. We do not know what affect this connection might have on the heart rate so it is very possible that a repetition of this experiment with music unknown to the subject may still be supported by data.
