Answer: Dr. Johnson is conducting an experimental study to test the effectiveness of a new therapy for individuals with arachnophobia, which is the fear of spiders. He is measuring the pulse rate of the participants before and after the therapy as an indicator of their fear response when confronted by an actual spider. The data collected will likely be used to determine if the therapy is effective in reducing the participants' fear of spiders as measured by their pulse rate.
It is important to note that while pulse rate is a good indicator of fear response, it is not the only indicator of fear and it is also not a definitive measure of the effectiveness of the therapy. Other factors such as self-reported fear, behavioral changes, and physiological changes should also be considered to get a comprehensive understanding of the therapy's effectiveness.
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