Final answer:
The research described in the question is observational research, where the researchers observed customer behavior without manipulating any variables to determine the effect of packaging on purchase decisions.
Step-by-step explanation:
The form of research described in the question is observational research. Observational research involves gathering data by observing individuals or groups without manipulating any variables. In this case, the researchers simply placed two different packages of cat food on a shelf and observed which package customers reached for first. This method allows the researchers to understand how packaging affects customer purchase decisions in a real-world setting.
Observational research involves systematically observing and recording behaviors, events, or phenomena in their natural settings. It is used in various fields such as psychology, anthropology, and marketing to gather real-world data, understand behavior, identify patterns, and inform scientific or business decisions through direct, unobtrusive observation.