The term âcarrier oilâ encompasses hundreds of different oils and butters. In the most basic sense, the word âcarrierâ serves to distinguish oils that are not âessentialâ oils. Common carrier oils include olive oil, coconut oil, shea butter, cocoa butter, grapeseed oil, canola oil, sweet almond oil, walnut oil, and more. The oils in this category vary wildly in terms of texture, colour, thickness, nutritional composition, and scent, but generally they are our base oils/butters.
In order to proceed with his research, Ebbinghaus had first to invent stimulus materials. These needed to be relatively simple, neutral as to meaning, and homogeneous. They needed to be available in large numbers and to allow quantitative manipulation of the amount of material to be retained.
We can look at the Avery-Griffith experiment to see how scientists meet these criteria. Frederick Griffith's work led to the discovery of a transforming principle that could change bacteria from one strain to another. Oswald Avery set out to identify what that transforming principle was. He designed an experiment that would test all of the possible factors.