Variables are vital part of an eye tracking experiment. A change is anything the can readjust or be changed. In various other words, that is any factor that can be manipulated, controlled for, or measured in one experiment.Experiments contain different types of variables. We will current you with several of the main species of experimental variables, your definitions and also give you examples containing all variable types.

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Types of experimental variables:

Independent variables (IV): These are the components or problems that you manipulate in an experiment. Your hypothesis is that this variable reasons a direct effect ~ above the dependency variable.Dependent variables (DV): These space the variable that you observe or measure. As you differ your independent change you watch what wake up to your dependent variable.
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Extraneous variable: one extraneous varable is any kind of extra aspect that may influence the outcome of an experiment, also though the is no the emphasis of the experiment. Ideally, this variables won’t impact the conclusions drawn from the outcomes as a cautious experimental style should equally spread influence across your check conditions and stimuli.Nevertheless, extraneous variables should always be considered and controlled when possible as lock may present unwanted variation in your data. In this case, you have to tweak her design and procedure to be able to keep the variation continuous or find a strategy to monitor its influence (constant or managed variables).All experiments have actually extraneous variables. Here are some instances of different species of extraneous variables:aspects the the setting where the data repertoire will take place, e.g., room temperature, lift noise level, light levels;differences in participant characteristics (participant variables); andtest operator, or experimenter behavior during the test, i.e., their instructions to the test participants space not continuous or they offer unintentional hints of the goal of the experiment come the participants.
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Figure 2. Display screens the impact of extraneous variables on the relationship in between the independent and dependent variables.


regulated (or constant) variables: space extraneous variables the you manage to keep consistent or regulated for during the food of the experiment, as they may have an impact on your dependent variables together well.Participant variables: Participant variables can be identified as the differing individual qualities that may affect how a participant responds in one experiment. Instances of participant variables encompass gender, age, ethnicity, socioeconomic status, literacy status, mood, clinical diagnosis etc.Stimulus variables: this are particular features of your stimulus or group of stimuli the are component of the context in which the behavior occurs. These are regularly an expression of or a subset of her independent variables and covariates. Examples incorporate the number of items, items category, stimulus crowdedness, color, brightness, contrast, etc.

Operationalizing variables

Before you start your experiment, you require to have actually a clear an interpretation of, and strategy for, exactly how each variable will certainly be measured and also recorded. This procedure is called variable operationalization.

For example, you room interested in studying attitudes towards food, visual attention, and food choice. In your first study, your objective is to investigate “the result of an individual health goals on visual attention to different food groups”.

The an initial part of your objective, “the impact of an individual health goals…”, consists of an live independence variable. To operationalize the you have to ask yourself the adhering to questions: What is a an individual health goal? have the right to you quantify and also measure it? have the right to you rest it down into unique categories? just how will girlfriend collect and record that value? because of the nature that this term, your variable will certainly most likely be created of 2 or more categories (e.g. Shed weight, save weight, gain weight etc.) and its value tape-recorded by means of a questionnaire or interview. Notice that in this example, the independent variable is likewise an intrinsic attribute that a participant and also thus details to the individual, as a result, this change can also be classified together a participant variable.

The next component of your study objective “…on visual attention to different food groups”, consists of your dependency variable. Once again, friend will have to ask yourself the adhering to questions: What is intuitive attention? how do ns measure it? just how is food grouped? just how will we stand for the different groups in the stimuli? Which group strategy is appropriate to my objective? The term “visual attention to” have the right to be operationalized right into one or much more relevant visual habits measures that can be quantified and measured continuously. Because that example, eye tracking metrics choose fixation duration, continuous count, and also dwell time can carry out you through information about the intuitive engagement and bias towards various items in your stimulus. The “… different food groups” term will most most likely be operationalized as food varieties aggregated right into categories (e.g. Vegetables, red meat, dairy) and also displayed on photo stimulus. Because you room manipulating the contents of the stimulus and the manipulation affect the context in i m sorry the habits occurs and also the viewing behavior itself, her stimulus categories will be part of your set of elevation variables and also simultaneously a stimulus variable.


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Figure 3. Reflects one possible outcome of the operationalization of the different variables in the example study. The target of this examine is to uncover out what effect an individual health goals have actually on a person"s visual fist to different food groups.

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In the example above, the participant’s "current hunger state" is a variable that may impact visual behavior and also attention bias. If a test participant ate their meal a long time ago and feels hungry, their fist may come to be focused top top high calorie food groups, even though they can normally not look to those food items once they"re satisfied. If you decision to disregard it, it becomes an extraneous variable in her experiment and also may impact the relationship in between your independent and dependent variable. On the other hand, if you decide to resolve it and control for it, friend will additionally have to operationalize it, e.g. You can measure it as the elapsed time due to the fact that the last meal. If you climate ask all your examine participants to eat a meal within 1 hour prior to your test, this variable becomes a managed variable, together you shot to standardize the level the hunger across your independent variable groups.