Exploring the Challenges and Opportunities of Theory-Laden Observation and Subjectivity: A Key NOS Notion

One key NOS aspect often recommended for inclusion in school science programs is the issue of subjectivity and bias (sometime called theory-laden observations) when viewing the world. Everyone has some expectations or prior “theories” when making observations and students should have opportunities to explore this notion and understand the role of theory-laden observations in science. The purpose of this chapter is to help teachers understand this issue both with discussion of the issue and an example. First, we explore the idea of subjectivity related to the way in which all humans—scientists included—engage in observing. In many cases, what observers expect to see can be helpful in allowing the observer to ignore things that are not important. In other cases, when observers expect to see something, they do. Second, this chapter reports the results of an experiment in which observers expected to see the heart of a tiny aquatic crustacean—daphnia—speed up or slow down when exposed to chemicals such as nicotine or alcohol. This experiment demonstrated the expectancy effect because, although students reported the anticipated results, there were no active chemicals involved but students believed that alcohol or nicotine was introduced to the daphnia.