What does the word manipulated variable mean?

Answer 1

A manipulated variable is essentially the same as an independent variable in the context of scientific research.

Here's an example. Suppose you were studying how quickly rats can navigate a maze to find food and you wanted to know the effect of hunger level. You could keep one group of rats hungry for four hours and another group hungry for eight hours then allow each rat in the two groups to find its way through the same maze to a quantity of food. You would measure the time it took each rat to find the food. The manipulated variable would be the time that a rat had been kept hungry.