Researchers gave participants varying amounts of a new "memory" drug. Then they gave them a story to read, and measured their scores on a quiz. The would be the independent variable (IV), and the would be the dependent variable (DV).

The correct answer is amount of the drug; quiz scores

Independent variable

these variables influence, affect or determine other variables. it is a determining factor, condition or cause for a given result, effect or consequence. it is the factor manipulated by the researcher in order to determine the relationship of the factor with the observed phenomenon, to see what influence it has on a possible result.

Dependent variable

they are values (phenomena or facts) to be discovered or explained, by virtue of being influenced, determined or affected by the independent variable. it is the factor that appears, disappears, increases or decreases as the researcher modifies the independent variable; it is the property that or factor that is an effect, result, consequence or response to something that has been manipulated (independent variable).