System Variables Table

All system variables are listed below with an explanation, but they are also shown in the main variable menu. Clicking on a variable will open a menu to the right of the screen with data type information and a short description. They can be sorted in the menu according to user preference.

Variable NameData TypeDescription
Subject_NrNumericSubject_Nr is a global counter of participants in a study. This can be used to do custom between-subject randomization and to infer the overall number of participants in a study.
Trial_NrNumericTrial_Nr holds the current value of the trial number for the current task. This can be used to infer whether the participant is currently performing the first, second, third, (and so on) trial in this task.
Trial_IdNumericTrial_Id holds the current value of the trial id for the current task. This can be used to infer which trial is currently being performed by the participant.
Condition IdNumericCondition_Id holds the current value of the condition id for the current trial. This can be used to infer which condition is currently being performed by the participant.
Subject_CodeStringSubject_Code is a unique string for each subject / session across all experiments running on Labvanced. This can be used to uniquely identify each participant or session.
Group_NameStringGroup_Name holds the value of the subject group name for each participant. This can be used to infer to which subject group each participant is assigned to.
Session_Start_TimeDateSession_Start_Time records the start date and time of the current participant session in the participant's local time, specifying their UTC time zone.
Session_End_TimeDateSession_End_Time records the end date and time of the current participant session in the participant's local time, specifying their UTC time zone.
Session_NameStringSession_Name holds the value of the session name for the current session. This can be used to infer which session is currently being performed by the participant.
Session_NrNumericSession_Nr holds the current value of the session number for the current session. This can be used to infer whether the participant is currently performing the first, second, third, (and so on) session.
Block_NameStringBlock_Name holds the current value of the block name for the current session. This can be used to infer which block is currently being performed by the participant.
Block_NrNumericBock_Nr holds the current value of the block number for the current session. This can be used to infer whether the participant is currently performing the first, second, third, (and so on) block in this session.
Task_NameStringTask_Name holds the current value of the task name for the current block. This can be used to infer which task is currently being performed by the participant.
Task_NrNumericTask_Nr holds the current value of the task number for the current block. This can be used to infer whether the participant is currently performing the first, second, third, (and so on) task in this block.
TimeMeasure_MeanNumericTimeMeasure_Mean provides an estimate of how precisely reaction times can be measured by the participants computer/device. The provided value is a mean offset of several reaction time measurements in milliseconds. It can be used to infer how precisely stimuli were shown on the screen.
TimeMeasure_StdNumericTimeMeasure_Std provides an estimate of how reliable/consistent reaction time measurement is throughout the experiment. The provided value is a standard deviation of several reaction time measurements in milliseconds. It can be used to infer how comparable reaction time measurements are across trials and conditions.
Crowdsourcing_CodeStringCrowdsourcing_Code holds the value of the unique crowdsourcing code, typically shown to the subject at end of the experiment to complete the crowdsourcing session and claim the payment.
Crowdsourcing_SubjIdStringCrowdsourcing_SubjId holds the value of the unique identification code for each crowdsourcing participant. This can be used to later on create a reference between crowdsourcing data on Labvanced and the external crowdsourcing service (e.g Mechanical Turk).
Subject_Nr_Per_GroupNumericSubject_Nr_Per_Group is a counter per subject group in a study. This can be used to do custom between-subject randomization and to infer the current number of participants within each subject group.
Role_IdNumericRole_ID is used for multi user/multi participant studies to refer uniquely to one of the participants of the study. This can be used to present different frames and roles to different participants within the same task/experiment.
Multi_User_Group_IDNumericHolds a unique group ID for multi-user studies. This helps researchers identify which subjects participated in a group together.
Displayed_LanguageStringDisplayed Language holds the value of the selected display language (if there were 2 or more languages to select from). This value can be used to show different content, i.e. texts for different language settings.
Window_Width_In_PixelsNumericHolds the value of the participant's browser window width in pixels.
Window_Height_In_PixelsNumericHolds the value of the participant's browser window height in pixels.
Screen_Width_In_PixelsNumericHolds the value of the participant's screen width in pixels.
Screen_Height_In_PixelsNumericHolds the value of the participant's screen height in pixels.
Pixel_Density_PerMMNumericThe number of pixels in 1 millimeter of the participant's screen. Helps researchers infer the physical size of the participant's screen.
Experiment_VersionNumericA counter that increases each time the experiment is saved. Denotes the version of the experiment that is being edited.
Distance_To_Screen_In_CMNumericThe value of the distance from the participant to their device's screen in centimeters. Obtained during eye/headtracking calibration.
Browser_SpecStringBrowser_Spec holds the value of the browser used by the participant to perform the experiment. This can be used to later analyze possible differences between browsers. Allowing/forbidding certain browsers can be done via the study settings.
System_SpecStringSystem_Spec holds the value of the operating system/device used by the participant to perform the experiment. This can be used to later analyze possible differences between operating systems/devices. Allowing/forbidding certain operating systems/devices can be done via the study settings.
Agent_SpecStringAgent_Spec holds the complete String of the User-Agent-Browser-Specification. This can be used to get more detailed information about the participant's system specifications.
BrowserVersion_SpecNumericBrowserVersion_Spec holds the value of the browser version used by the participant to perform the experiment. This can be used to later analyze possible differences between browser versions.
Is_FullscreenBooleanA true/false indication of if the experiment is currently being viewed in fullscreen mode. Can change throughout the course of the experiment.
Always_FullscreenBooleanA boolean value that is true as long as the participant keeps the experiment running in fullscreen mode. This can be used to pause/quit the experiment when a participant leaves fullscreen mode.
SelectedAgeNumericA numeric variable that holds the value of the age selected during the pre-study questionnaire. Does not populate if age is not one of the required values in the questionnaire.
SelectedLocationStringA string variable that holds the value of the location selected during the pre-study questionnaire. Does not populate if location is not one of the required values in the questionnaire.
SelectedLanguageStringA string variable that holds the value of the language selected during the pre-study questionnaire. Does not populate if language is not one of the required values in the questionnaire.
Group_NrStringHolds the value of the "subject group nr" for each participant. This can be used to infer to which subject group each participant is assigned to.
CompletedStringHolds the information of whether the data recording was successfully completed or not.