Knowledge Base

Program Trial Control

Visualizing Trial Control Data

Choose Trial Control State to select the time between events occurred during the trial. For example, From Action Light On To Condition In Trigger Zone True. This will show the time interval from when the light switches on to when the animal enters the Trigger zone.

1. Start a trial. Watch the Trial Control Events or States in the Analysis Results and Scoring Pane at the bottom of your screen.
2. Create an Analysis profile and use the Trial Control event/state/variable and other dependent variables to specify the events you want to visualize. See page 176 for details.
3. To visualize the trial, choose Analysis > Results > Plot Integrated Data. Trial Control data are visualized as vertical segments (for events, with no duration) or horizontal bars (for states, with a duration) along the time line. Examine the data and check that EthoVision XT has responded as expected.
4. You can also check when exactly a condition becomes active or true, or when a command is given by looking at the Trial Control Events pane at the bottom-right corner of your screen. Select an Arena name from the list to visualize the sequence of Trial Control for that arena.

Play the track. The red hairline moves along the sequence and shows at what point Trial Control is. Play the track frame-by-frame to see when exactly a condition becomes true, or a command becomes active.

In the following example, a Trial Control sequence is defined:

Condition: In trigger zone → Action: Drop pellet → Condition: In feeder zone.

Play the track until the cursor gets between Condition: In trigger zone - becomes false and Condition: In trigger zone - becomes true. This is the time when the condition is activated and the program waits until the animal enters the trigger zone.

At 15.48 s the condition becomes true. The program executes the instructions that follow (Action: Drop pellet) and positions at the next condition (In feeder zone) until that becomes true too.

5. Make the necessary corrections to the Trial Control rules and start again from step 1.

Notes

For a clear overview of the Trial Control events occurring during a trial, for each Trial Control box (except the Rule End box) define three dependent variables:

• Trial Control event (becomes active): Under Element, choose which box to test, and under Event, choose becomes active. This marks the time when an action is taken, a condition is evaluated, or a sub-rule is activated.
• Trial Control event (becomes inactive): Under Element, choose which box to test, and under Event, choose becomes inactive. This marks the time immediately after an action is taken (this is usually not distinguishable from the time the action is taken), a condition is met, or a sub-rule is completed.
• Trial Control state: Select From when the box becomes active To when the box becomes inactive. This will display a colored bar that marks the time that the box is activated up to when it is deactivated.

Define also one or more In Zone dependent variables to monitor the position of the animal.

Once you have carried out a trial, the Trial Control Settings used for that trial are locked. To edit them, either delete the trial acquired or make a copy of the Trial Control Settings (right-click the Trial Control Settings in the Experiment Explorer and select Duplicate).

To check at what time an action is taken or a condition is met, you can also export the Trial Control events and the Hardware log data (see page 193).

You can also test your Trial Control Settings by providing visual/audible feedback during the trial. Define an action box that calls up some feedback once the program has reached a specific point in the Trial Control sequence. Insert this box immediately to the right of the condition/action/rule reference box that you want to test.

To test hardware devices, see page 123.

Apply Trial Control to Your Trials

To apply Trial Control to your trials, make sure that the Trial Control Settings profile containing that logic is highlighted in blue in the Experiment Explorer.

Test your setup thoroughly before carrying out the actual trials (see page 47).

Setups with Multiple Arenas

Trial Control is applied to each arena independently.

Locked Trial Control Settings

When a Trial Control Settings profile is used for acquiring at least one trial, it becomes locked. Locked settings are indicated by a lock symbol in the Experiment Explorer, and cannot be edited. To edit a locked Trial Control Settings profile, make a copy of it and edit this copy.

Tracking from Pre-Recorded Video Files

When you track from video files, Trial Control checks conditions using video time instead of real time.

• Conditions based on time: If you select the Detection Determines Speed option, Trial Control is carried out at the speed set by EthoVision in order not to skip video images. This results in the video playing faster or slower than normal (1x), depending on the processor load necessary to detect subjects. For example, if detection requires little processor work, the program tracks the subject faster than normal. A time condition (for example, 60 s) is therefore met earlier than at real time.
• Using clock time: If you define a condition based on clock time, or schedule a sub-rule with clock time, this is translated into the video start time — that is, the date and time the video file used for tracking was created.

Example 1: You set a Time condition to start tracking After clock time 11:30. The video file was created on March 6, 2008 at 11:00. Once you start the trial, the condition is met half an hour later in the video. If you had set to start tracking After clock time 10:30, tracking would start immediately after starting the trial.

Example 2: You set a sub-rule to start at 10:00 (1st day). The video file was created on March 6, 2008 at 11:00. Once you start the trial, the sub-rule never starts, because the planned start occurs before the initial time of the video. To make a sub-rule start when tracking from that video, set the start time between 11:00 and the video end time.

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