Knowledge Base

Variables (Continued)

Rotation of the body axis, rather than that of body points. In the Body Points tab, select the body point you want to use to calculate rotation.

Frequently-Used Statistics

• Frequency - To base your condition on the number of rotations occurred.
• Latency to First - To base your condition on the time from the moment the condition becomes active to the first rotation.

Example: Stop tracking when the first rotation event occurs less than one minute from the moment the condition becomes active.

More About Conditions Based on Dependent Variables

JavaScript Variables

In the Condition window, click the Settings button and enter the JavaScript code that, when processed during acquisition, produces an output value. The condition will compare that value with those in the settings. This value can be Continuous, a State, or an Event depending on which JavaScript variable you use.

In the Actors tab, select the subject for which to calculate the JavaScript variable value.

Example: You want to create a condition that is based on the body area of the subject. Because EthoVision XT does not provide the body area in the Trial Control Settings, you can extract this value with a JavaScript variable of type Continuous that contains the command GetArea(). The condition could be for example "Body area > 2000" where 2000 is specified in the condition settings.

A few more examples:

• Create a condition that becomes true when the Body length exceeds a specific value for some time.
• Create a condition that becomes true when the number of subjects in a zone exceeds a specific value.
• Create a condition that becomes true when the distance of a focal subject to the nearest neighbor is smaller than a threshold value.

Examples of JavaScript Variables

Browse to my.noldus.com (either log in or register first), then choose Downloads > EthoVision XT > Versions. Download the file EthoVision XT - Full Installation Disc.zip. Next, extract the contents of the zip file, open Drivers and Tools > Utilities > JavaScript custom variables.

More examples are available on GitHub: https://github.com/noldus/EthoVision-JavaScriptCustomAnalysis.

Contact Noldus if you need to define a variable tailored to your research.

Distance Between Subjects

In the Condition window, click the Settings button. In the Actors tab, select the subject and its body point that you want to use to calculate the distance to another subject. In the Receivers tab, select the other subject and its relevant body points.

Example: To make an action when ano-genital sniffing takes place, use a condition box with a minimal distance between the nose point of one subject and the tail base of the other. Select Current as Statistic, then click Settings. Under Actors, select the focal subject and Nose-point. Under Receivers, select the other subject and Tail-base.

Proximity

In the Condition window, click the Settings button. In the Proximity tab, specify the criteria to define proximity. In the Actors tab, select the focal subjects and their body points that you want to use to calculate proximity to other subjects (Receivers). In the Receivers tab, select the other subjects and their relevant body points.

For dyadic interactions, select Subject 1 under Actors and Subject 2 under Receivers.

Frequently-Used Statistics

• Current - To base your condition on the current proximity state. Example: Take an action when the nose-point of subject 1 is in proximity of tail-base of subject 2.
• Frequency - To base your condition on the number of times the subjects were in proximity of each other.
• Current Duration - To base your condition on the duration of the current occurrence of In Proximity.
• Cumulative Duration - To base your condition on the cumulative duration of the selected proximity state up to that time.
• Latency to First - To base your condition on the time from the moment the condition becomes active to the first occurrence of the chosen proximity state. Example: Take an action when the latency of Nose point of subject 1 is in proximity of Tail base of subject 2 is longer than one minute.

Body Contact

In the Condition window, click the Settings button. In the Body Contact tab, specify whether the condition is based on body contact or no contact. In the Actors tab, select the subjects that should be in contact (or not in contact) with any other for the condition to become true. From the Statistics list, choose the statistic to be used and the value that makes the condition true. For example, if you want to create a condition that is met when body contact lasts 10 seconds without interruption, choose Current Duration >= 10 s.

Frequently-Used Statistics

See the statistics for Proximity.

Note: When you select multiple subjects in the Actors tab, the condition is evaluated separately for each subject and then combined according to what you select from the With list. If you select Subject 1 and Subject 2 in the Actors tab, and select All selected subjects from the With list, the condition is met when both Subject 1 and Subject 2 are in contact with any subject (thus not necessarily in contact with one another).

Relative Movement

In the Condition window, click the Settings button. In the Relative Movement tab, specify at which maximum distance the subjects should be considered as 'interacting', and the criteria to define relative movement. In the Actors tab, select the focal subjects and their body points that you want to use to calculate relative movement to/from other subjects. In the Receivers tab, select the other subjects and their relevant body points.

Frequently-Used Statistics

See the statistics for Proximity.

Net Weighted Movement

In the Condition window, select Current as Statistic, then click Settings. In the Net Weighted Movement tab, specify at which maximum distance the subjects should be considered as 'interacting'. In the Actors tab, select the focal subject and its body point that you want to use.

Source: EthoVision XT 18 - THC - Trial and Hardware Control, Noldus Information Technology