# 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 condition in box B is applied separately for each arena. As soon as an the subject is detected in an arena, tracking starts for that arena, not the others. As a result:

▪This way 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.

Part of the Start-Stop trial rule of the Trial Control Settings when selecting Behavior recognition in the Experiment Settings.

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.