Knowledge Base

Control Tracking

Start Track Conditions

You can configure when tracking begins using the following conditions:

• Frequency — Start tracking when the animal has visited the zone a number of times.
• Latency to First — Start tracking when the latency to its first visit to the zone is less than or greater than a specific time.

To Use a Different Start Track Condition

Click the Condition - In Zone box and press Delete, then choose another condition (see the examples below).

Example 1: Start tracking exactly 1 minute after clicking the Start Trial button.

1. Click the Condition - In Zone box and press Delete.
2. Under Conditions, click the button next to the variable you want to use (Time in this example), and select the options you require.
3. Insert the new box in the sequence and re-connect the boxes. See Connect Two Boxes.

Example 2: Start tracking at a time you are not in the lab, for example at 23:00.

1. In step 2 above, click the button next to Time, choose After Clock Time, and enter 23:00:00.
2. Before leaving the lab, choose Acquisition > Open Acquisition and click the Start Trial button. The program waits until 23:00 to start tracking.

Examples

Example 1: Start tracking immediately when you start the trial.

1. Click the condition box and press Delete.
2. Reconnect the first box with the second one. See Connect Two Boxes.

Example 2: Start tracking when both (all) subjects are in the arena.

1. This assumes that the experiment is set to multi-subject tracking.
2. Click the Settings button in the condition box.
3. In the window that appears, click the Actors tab and select the subjects that should be in the arena at the start of tracking.
4. Select All Selected Subjects.

Control the End of Tracking

Stop Tracking After Some Time

This option allows you to create tracks of fixed length. The default Stop Track condition is a Time condition. Click the Settings button, and choose the option you require.

• To stop tracking after some time, choose After a Time Of and set the time. For example, set 5 min if you want to track subjects for five minutes.
• To stop tracking at a specific clock time of the same day, choose After Clock Time and set the time required. To stop tracking after the current day, you must have the Trial and Hardware Control module.

Stop Tracking Based on the Behavior of the Subject

1. Click the Time condition box and press Delete.
2. Under Conditions, choose the variable that describes the behavior and click the corresponding button. For example, to stop tracking when the subject is in a zone, click In Zone.
3. Configure the variable and insert the new box in the Start-Stop Trial rule. See Insert a Box in a Trial Control Sequence.

To Set a Maximum Duration for Your Trials

If the conditions to stop the trial are never met, EthoVision XT waits indefinitely and the trial never ends. To prevent this from happening, define a maximum trial duration.

Example: In a Novel Object test, if the Stop Track box is preceded by a condition "when the subject enters the zone with the familiar object," it may happen that the subject completely ignores the familiar object and only pays attention to the novel object. In that case the condition to stop tracking is never met.

In the Maximum Trial Duration pane, select Use a Maximum Trial Duration and enter the maximum duration of the trial (in hours, minutes, or seconds). For information about the duration of trials tested with specific cameras and computers, see Resolution, Frame Rate, and Maximum Trial Duration. Longer trials and videos are possible in principle but they have not been thoroughly tested.

Stop Video Recording After Some Time

All the options above refer to stopping the trial when you do tracking. If you record video and then acquire the tracks (see Record Video, Then Acquire a Trial), the Maximum Trial Duration option will not work. This is because the Trial Control Settings, including the Maximum Trial Duration option, are not active when EthoVision XT just records video without acquiring data. You must stop video recording manually.

An alternative strategy is the following:

1. Set the Maximum Trial Duration (see above).
2. Acquire a trial live and save video.
3. The saved video has a fixed length. You can now use that video to redo tracking in the same experiment, or use that video in another experiment (set to offline tracking).

Notes

• Keep at least one condition between Start Track and Stop Track. If you do not do this, tracking stops immediately after tracking starts, resulting in no data.
• If you do not see the Maximum Trial Duration pane, click the Show/Hide button on the toolbar and select Maximum Trial Duration. If the text in this pane is grayed out, it means that Trial Control Settings are read-only. Open another Trial Control Settings profile or create a new one.
• Instead of using a maximum trial duration, you can also define a condition based on time and place it immediately before the Stop Track box. This way you set the exact duration of the tracks. See Stop Tracking After Some Time.
• For more information on conditions, see Overview of Conditions in the EthoVision XT 19 - Trial and Hardware Control - Reference Manual.