You are interested in finding out the effect that crowding has on people's moods. you conduct a study in a psychology research lab using two types of participants — participants who have to wait in a crowded waiting room before completing a measure of their mood, and participants who wait in an empty room before completing the same measure. which type of research did you conduct?

both experimental and laboratory research

Explanation:

Experimental research is any research conducted with a scientific approach, where one set of variables is kept constant, while the other set of variables is measured as the subject of the experiment. The simplest example of an experimental investigation is a laboratory test. Whenever research is conducted under scientifically acceptable conditions, it is qualified as an experimental investigation.  On the other hand, laboratory researches are conducted indoors or outdoors, in artificial or real environments, in all cases, require an appropriate environment, previously established and according to the study to be performed.

Based on this conceptualization, we can see that the research shown in the above question is experimental and laboratory research, since the variables are constant and the research is performed in controlled locations.