An experimenter studies the influence of ingesting sugar on memory. Children are randomly assigned to either a low calorie ice cream cone (low sugar condition) or a Ben and Jerry's cone (high sugar condition). They are then asked to learn ten vocabulary words that they did not previously know, and then number or trials it takes to learn them is measured. The independent variable in this experiment is:

(A) the number of children in each condition
(B) the type of cone
(C) the gender of the participant
(D) the number of trials to learn

When we do a research, there are two main variables to take into account. These variables are the independent variable and the dependent variable.

The independent variable is the one that we can control as researches and that will have an effect on another variable.
The dependent variable is the one that we don't really have control on and is the one that gets affected by the independent variable.

In this example, the experimenter studies the influence of ingesting sugar on memory.

The variable that the experimenter will control is the cone he will give to children (low calorie or high sugar) and therefore this is the independent variable.

On the other hand, he will later test if there are differences in memory between both groups (by counting the number of trials it will take them to learn new words) this variable, he won't be able to control it, so this is the dependent variable

Thus, the independent variable as we said before will be b) the type of cone.