Argument53 【Persistence 小组】第26次作业

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53Thirteen years ago, researchers studied a group of 25 infants who showed signs of mild distress when exposed to unfamiliar stimuli such as an unusual odor or a tape recording of an unknown voice. They discovered that these infants were more likely than other infants to have been conceived in early autumn, a time when their mothers' production of melatonin—a hormone known to affect some brain functions—would naturally increase in response to decreased daylight. In a follow-up study conducted earlier this year, more than half of these children—now teenagers—who had shown signs of distress identified themselves as shy. Clearly, increased levels of melatonin before birth cause shyness during infancy and this shyness continues into later life.


In this argument, the author concludes that increased levels of melatonin produced by the pregnant mother cause shyness of the child during infancy which continues into later life. To support this claim, the author cites a study conducted 13 years ago, which showed signs of mild distress from infants who were exposed to unfamiliar stimuli and the infants’ mothers produce more melatonin than others. Additionally, the author provides a follow-up study reporting that these children considered themselves as shy. A scrutiny would reveal how groundless the conclusion is.

In the first place, the evidence presented in the beginning demonstrates a correlation between increased level of melatonin before birth and signs of mild distress during infancy, based on which the author concludes that the former is the cause of the latter. However, the author fails to rule out other possible explanations for the mild distress. For example, it is possible that these infants’ brain functions are affected due to premature delivery. Any of these factors, or other genetic disorders, might lead to the signs of distress. Without ruling out all other such factors it is unfair to conclude that increased melatonin is responsible for the distress.

In the second place, the author unjustly equates the mild distress with shyness. However, it is entirely possible that the mild distress showed by the infants is caused by the terrific aspects of the stimuli, such as harsh sound of the tape recording or horrible smell which may bring about distress even when these infants are familiar with such stimuli, rather than by the unfamiliarity which is responsible for shyness. In short, since the author has not taken into account these possibilities, I simply cannot accept the conclusion.

In the third place, there is no information about how the study was conducted. Without knowing whether a group of 25 infants was representative of the general infants and the size of the sample was sufficient enough, it is impossible to confidently apply the studies’ results to the general. Therefore, the author’s conclusion based on this study is questionable.

In the final analysis, the arguer fails to establish a causal relationship between increased level of melatonin and signs of mild distress. To better evaluate this argument, I need more evidence concerning that mild distress showed by the infants was resulted from unfamiliarity and the study’s results are statistically reliable.