Variable - aspect of a testing condition that can change or take on different characteristics with different conditions: variables are tangible: during, frequency, rate etc. , theoretical concepts are intangible: hunger, love, motivation, anxiety. Dependent variable - a measure of the subject"s behaviour that reflects the independent variable"s effects. Frequency - the number of times that a behaviour is performed. Rate - the number of times that a behaviour is performed relative to time. Duration - the amount of time that a behaviour lasts. Latency - the amount of time between an instruction and when the behaviour is actually performed. Topography - the shape or style of the behaviour. Force - the intensity or strength of a behaviour. Locus - where the behaviour occurs in the environment. Independent variable - the condition manipulated or selected by the experimenter to determine its effect on behaviour. Levels - the different values of an independent variable.