The stamp effect means that when the research topic can be related to a person's specific things, activities and emotions, the accuracy of the inference results will be greatly improved. The reasoning materials are specific, and the reasoning is easier. The reasoning materials are abstract. The reasoning is more difficult. According to the definition of appeal, Which of the following are not part of the stamp effect:. ['The first artificial aircraft in the world was designed by people by studying the characteristics of bird flight.', 'Archimedes found that the more the body sinks in the shower, the more water overflows from the basin, and from this, he discovers the "buoyancy law".', 'It is found that when sunspots are active, severe weather will occur on the earth, so sunspots are considered a precursor to extreme weather.', 'Galileo freely dropped two iron balls of different weights from the same height on the Leaning Tower of Pisa at the same time, and two iron balls landed at the same time, confirming that the speed of free fall has nothing to do with mass.']