Knowledge Base

The Default Start-Stop Trial Rule

How To Access The Start-Stop Trial Rule

• Choose Setup > Trial Control Settings > Open and select an existing Trial Control Settings.
• In the Experiment Explorer, click one of the Trial Control Settings.

With this rule, you control the start and stop of data acquisition (tracking).

What The Start-Stop Trial Rule Means

The sequence of boxes A to F can be read as follows:

1. When you start the trial, for example by clicking the Start Trial button, box A (Rule Begin - Start-Stop Trial) is activated. Control passes immediately to box B.
2. EthoVision XT checks that the condition in box B (Condition - In Zone) is true. The condition states that the center point of the subject (or of any subject in the same arena) must be detected in the arena for an uninterrupted period of one second. When you start the trial and the subject is not yet in the arena, the condition is false. EthoVision XT waits until the subject has been detected for one second. At that time, the condition becomes true. Control passes immediately to box C. Note: In special cases this box is absent or has different settings. See The Start-Stop Trial Rule in Special Cases.
3. When condition B becomes true, box C (Action - Start Track) is activated, and tracking starts.
4. Control passes to box D (Condition - Time). EthoVision XT checks that the condition is met. This condition is set to wait indefinitely, so that tracking stops when you give the stop command, or when the end of the video file has been reached, or when the maximum trial duration has been reached. See Control the End of Tracking.
5. When one of the events specified above occurs, box E (Action - Stop Track) marks the end of the tracks in the arena.
6. Box F (Rule End - Start-Stop Trial) marks the stop of the trial; it does not take any action.

Notes

• If the condition in box B is not met immediately, the time that tracking starts (C) is different from the time that the trial starts.
• The Start-Stop Trial rule only works when you acquire data (live or offline). If you only record video, the Start-Stop Trial rule is inactive. You must start and stop video recording manually.

See Also

• Trial Vs. Track
• How the Trial Control Instructions Are Executed
• The Start-Stop Trial Rule in Special Cases

The Start-Stop Trial Rule In Special Cases

Multiple Arenas

When multiple enclosures are defined as separate arenas, the default Start-Stop Trial rule is applied for each arena separately. This means that the condition in box B is applied separately for each arena. As soon as the subject is detected in an arena, tracking starts for that arena, not the others. As a result:

• You do not have to release all the animals at the same time.
• Tracking may start at different times in different arenas in the same trial, depending on when a subject is released in its arena.

See Also

• Trial Control in Multiple Arenas

Multiple Subjects In The Same Arena

When multiple subjects are present in the arena, tracking starts when the first subject is found. Therefore, tracking starts for all subjects at the same time, even if the others are not yet in the arena. For those subjects, the track starts with a number of missing samples, until the subject is found.

To start tracking only when all subjects are found in the arena, and thereby avoid missing samples at the beginning of the track, see Start the Trial in the Social Interaction Test.

With DanioVision

If you create a DanioVision experiment, the Condition - In Zone box is not present. Tracking starts as soon as you start the trial.

With Activity Analysis

If you select Activity Analysis under Analysis Options in the Experiment Settings, the Condition - In Zone box is removed from the default Start-Stop rule. To carry out tracking and activity analysis simultaneously, and start tracking when your subject is detected in the arena for a specific time, insert a new In Zone condition box in the Start-Stop rule.

Note: If you also select Behavior Recognition in the Experiment Settings, the Start-Stop rule is as described below.

With Behavior Recognition

If you select Behavior Recognition under Analysis Options in the Experiment Settings, a Time condition is added between the Condition - In Zone box and the Action Start Track box. This means that EthoVision XT waits 3 seconds after detecting the animal for the first time, before starting actual tracking. This is done because the behavior recognition algorithms need a number of video frames equivalent to about three seconds before the current frame in order to recognize behavior.

The time condition "After a time of 3.0 s" is removed automatically from a Trial Control rule if you deselect Behavior Recognition in the Experiment Settings.

Control The Start Of Tracking

To Modify The Start Track Condition

The default Start Track condition is a condition based on the variable In Zone. The condition becomes true when the subject is detected in the arena for one second.

1. Click the Settings button.
2. In the window that appears, specify in which zone the subject should be to start tracking. Click Settings and choose the zone. See details about the variable In Zone.
3. Specify the criterion (time, frequency in the zone, etc.). From the Statistic list, choose one of the statistics. See the details below.

Statistics Available

• Current Duration or Cumulative Duration to start tracking when the animal has been detected for some time in the zone. Current Duration is an uninterrupted period of time (for instance, the animal must be detected for 1 s without interruption). Cumulative Duration sums up all periods when the animal is in the zone since the start of the trial.
• Current to start tracking as soon as the animal is detected (one sample is sufficient). Note that this condition may become true also when noise is occasionally detected as a subject for a very short time, before the animal is released in the arena. Make sure that this does not happen.