Brain tumor . Depending on where it is, it can cause different types of hallucinations. If it's in an area that has to do with vision, you may see things that aren't real. You might also see spots or shapes of light. Tumors in some parts of the brain can cause hallucinations of smell and taste.
One of the key factors in this process is the identification and operational definition of variables -- traits, characteristics, or other measurable factors that can have different values -- that impact the phenomenon of interest. One is primarily interested in two types of variables: independent variables and dependent variables. The independent variable is the variable that is being manipulated by the researcher. For example, Dr. Harvey has a theory that the way that people dress affects how they are treated by others in the workplace.
Variables: Independent, Dependent, Controlled. Types of Variables in A Science Fair Project. A variable is part of an experiment that can change, such as amount of light, temperature, humidity, time changes, or plant growth. In an experiment, an independent variable is a variable that either changes on its own, or you purposely change it. The goal of an experimental investigation is to determine how changes in an independent variable affects another variable, which is called the dependent variable.