Then what does the second "It" refer to?

"Researchers in psychology follow the scientific method to perform studies that help explain and may predict human behavior. This is a much more challenging task than studying snails or sound waves.

It often requires compromises, such as testing behavior within laboratories rather than natural settings, and asking those readily available (such as introduction to psychology students) to participate rather than collecting data from a true cross-section of the population. It often requires great cleverness to conceive of measures that tap into what people are thinking without altering their thinking, called reactivity."

Q1. What does the first "It" refer to? It must be "This, or the much more challenging task", right?

Q2. Then what does the second "It" refer to? The first "It"(="the much more challenging task"? or "to conceive of measures that ~"