Answer:
Physiological
Step-by-step explanation:
The independent variable is the predictor, which the experimenter controls and manipulates, It is the characteristic of a psychology experiment that is manipulated or changed.
Natalie conducts an experiment in which she randomly assigns half the individuals to drink alcohol and half to drink tonic water that they think is alcohol, Natalie was manipulating the independent variables which is the alcohol and tonic water.
An independent variable is the variable that is changed or monitored to evaluate the effects on the dependent variable in a statistical experiment.