Knowledge Base

Working with Boxes in Trial Control

Insert a New Box

1. Release the mouse button. The new box is inserted.

Connect Two Boxes

1. Point the mouse to the center of the first box, press and hold the left mouse button and drag toward the center of the other box.
2. Release the mouse button when the pointer has reached the center of the other box. The two boxes are connected.

Operator boxes can have one, two or more input arrows; all other boxes have no more than one input arrow. All boxes can have one or more output arrows, pointing to different boxes.

Modify the Settings in a Box

Click the Settings button in the lower part of the box. Make the appropriate changes in the window that appears.

Delete a Box

1. Click the title of the box. The box border is highlighted.
2. Press Delete.

Delete a Group of Boxes

1. Draw a box around the boxes you want to delete, or click on the boxes you want to select while holding the Ctrl key.
2. Press Delete.

You cannot delete the Rule Begin box, the Rule End box, the Start Track box, or the Stop Track box.

Delete a Connecting Arrow

1. Click the arrow you want to delete. The arrow turns bold to show it is selected.
2. Press Delete.

You cannot delete the arrow connecting the Stop Track box and the Rule End box.

Apply Trial Control to Your Trials

Apply Trial Control Settings to a Single Trial

Before starting the trial, do one of the following:

• In the Experiment Explorer, make sure that the Trial Control Settings profile you require is highlighted in blue.
• In the Acquisition screen, under Settings, select the Trial Control Settings you require.

Test your setup thoroughly before carrying out the actual trials.

Apply Trial Control Settings to Multiple Planned Trials

Choose Setup > Trial List. For each trial planned in the list, select the Trial Control Settings you require in the Trial Control Settings column. For more information, see Prepare the Trial List for Batch Acquisition.

Further Information on Trial Control

Learn About

• How the trial control instructions are executed
• Trial control when tracking from video files
• Trial control in multiple arenas

What Do You Want to Do?

• View trial control instructions during acquisition
• Analyze trial control data

How the Trial Control Instructions Are Executed

When EthoVision XT Evaluates Conditions and Actions

During a trial, EthoVision XT evaluates the Trial Control Settings selected for that trial and checks the state of conditions and actions at each sample time. Note that the sample time depends on the chosen sample rate, not on the video frame rate.

How EthoVision XT Evaluates Conditions and Actions

The program remembers which Trial Control box was evaluated (active) in the previous sample. Depending on the type of this box:

• For a Condition box: EthoVision XT checks whether the condition at the current sample time is met. If it is not, the condition becomes false. The program waits until the condition is met. When this happens (condition becomes true), the program passes control to the next box in the sequence. The condition then becomes inactive.
• For an Action box: EthoVision XT carries out the action and passes control to the next box, which becomes active. Then the Action box becomes inactive.
• For sub-rules and sub-rule references, see the EthoVision XT 19 - Trial and Hardware Control - Reference Manual.

When a box becomes active, the previous box becomes inactive.

Notes

• Boxes combined in parallel using operators are evaluated at the same sample time, in unspecified order. This means that one cannot establish which condition is evaluated or which action is taken first.
• Actions on Trial Control variables are executed immediately. Actions on hardware devices are executed when all boxes that must be evaluated at that sample time have been evaluated.
• If a box being evaluated contains a condition that is immediately true, the program passes control to the next box. Therefore, within one sample time the program can pass control to two or more boxes to the right.
• When you stop the trial or the maximum trial duration has been reached, all Trial Control boxes are deactivated and hardware devices are reset. See Control the End of Tracking.
• When the Rule End box of the Start/Stop trial rule is evaluated, data recording stops. From that moment, Trial Control is deactivated, even in those sub-rules that were ongoing in the meantime.

How Trial Control Instructions Are Executed: Step-by-Step Example

The following steps describe an example of a Start-Stop trial rule:

1. Tracking starts, either manually or because a previous condition has been met.
2. Control passes to a Condition box (for example, "Is mouse on top of Shelter?"), which becomes active. The condition is evaluated. Since the condition is not met immediately, it becomes false.
3. The condition becomes true.
4. Control passes to the next box. In this case it is an Action box. Actions are taken immediately.
5. The Action box becomes inactive. The next box becomes active.

For clarity, steps 3 and 4 are described separately. In reality, when a condition is met it becomes inactive at the same time, and control passes to the next box.