Knowledge Base

Conditions (Continued)

Case Descriptions

• Case 2. The subject enters the zone after the condition becomes active, but at a time less than L. The condition is NEVER met because the latency is smaller than L.
• Case 3. The subject enters the zone after time L. This means that the latency of the first In zone is greater than L. The condition is met at that time.
• Case 4. The subject never enters the zone. The condition is NEVER met.
• Case 5. The subject enters the zone at a time less than L, then exits the zone, then enters again at a time greater than L. The latency of the first In zone state is less than L, thus the condition is NEVER met, no matter how many times the animal enters the zone.

As you can see there are many cases in which the condition is never met, including Case 5, which is due to the fact that only the first instance of In zone is taken under consideration.

Subjects in a Condition

Select the Subjects

1. In the Condition window, click the Settings button. In the variables properties window, click the Actors tab. In the Actors tab, you select the actors of the behavior.
2. Under Select, select the subject you want to base your condition on. If your condition is based on social interactions, select the focal subject in the Actors tab and the other subjects in the Receiver tab. Do so also for dyadic interactions (Subject 1 under Actors, Subject 2 under Receivers).

For dependent variables with discrete values like In zone, Movement, Mobility, Elongation, Proximity, Body contact, and Relative Movement, you can base your condition on the state of multiple subjects at the time the condition is evaluated.

If you select two or more subjects, select one of the two options from the list immediately below the Select box:

• All Selected Subjects. The state selected in the dependent variable properties window must be the same for all the actors simultaneously, in order for the condition to be met.
• Any Selected Subjects. The state selected in the dependent variable properties window must be true for at least one actor in order for the condition to be met.

3. If the Actors tab also contains the Body Points options, select one or more body points of the subjects selected above.
4. For the dependent variables of social interaction, a Receivers tab is also available. Click this tab and select the subjects that you have not selected under Actors.
5. Click OK to confirm your selection. You return to the condition window.

Notes and Examples

Example of choosing All Selected Subjects. The researcher wants to define an In zone condition that is met when Subject 1 and Subject 2 have been in a zone simultaneously for at least one minute.

Solution: In the Condition window, select Cumulative Duration as Statistic and enter >= 60 s. Click Settings and select the zone you require, then click Actors and select Subject 1 and Subject 2, finally select All Selected Subjects.

Example of using Any Selected Subjects. The researcher wants to define a Distance to zone condition that is met when one of the two subjects is at less than 5 cm from a novel object.

Solution: In the Condition window, select Current and enter <= 5 cm. Click Settings and select the novel object zone, then click Actors and select Subject 1 and Subject 2, finally select Any Selected Subjects.

Example with Actors and Receivers. The researcher wants to define a condition that is met when the nose point of Subject 1 has been close to at least one body point of Subject 2 for more than one minute.

Solution: Click the button next to Proximity and in the Condition window, select Cumulative Duration and enter the required value. Click Settings, then:

• In the Actors tab, select Subject 1 and de-select Subject 2. Under Body Points, select Nose-point only.
• In the Receivers tab, select Subject 2 and de-select Subject 1. Under Body Points, select all points and then Any Selected Points, since the condition must be met when Subject 1 is in proximity of at least one of Subject 2's body points.

When Is a Condition Met?

Dependent variables are calculated for each sample. When a condition based on dependent variables is met depends on a number of factors.

Effect of Outliers and Track Smoothing

Dependent variables used in conditions are not smoothed or filtered using the Lowess filter or the Minimum Distance Moved as they can be for data analysis. This means that outliers, nose-tail swaps, or even subject identity swaps can have severe effects on whether and when a condition is met.

If a condition of type In zone is defined which specifies Frequency of In zone A >= 1, then the condition is met the moment that the subject is wrongly detected in zone A, assuming that the condition box was active. Track noise reduction may solve the problem. In the Detection settings, click Advanced and under Smoothing set Track Noise Reduction to On. This applies an online smoothing effect as the subject is being tracked. Note that this change in the track cannot be reversed afterwards.

Effect of Missing Samples

Missing samples can also cause Trial Control to react later. For example, an In zone condition is met only when valid samples are found within the specified zone.

If a condition of type In zone is defined which specifies Current of In zone A = true, then the condition is met later than it would be if there were no missing samples.

If a condition of type In zone states "Current duration of not in zone longer than 1 s" (assuming a sample rate of 5/s, so 5 samples make up 1 second), then the condition does not become true, because there are only 4 samples for which the state "not in zone" was true.

Similarly, the condition Current value of In zone A = false may be met in the first missing sample period.

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