Knowledge Base

Conditions (Continued)

Creating Conditions Based on a Trial Control Variable

Tip: If you do not see Trial Control Variable, click the More button.

1. In the Trial Control Condition window, under Name, enter a Condition Name.
2. Under Condition is met when, select the Trial Control variable from the first list. If the variable has not been defined yet, define it first by clicking Variables.
3. Select the comparison operator (=, >, etc.) from the second list.
4. Do one of the following:
   • To compare the Trial Control Variable with another variable, or a numerical value, select that variable/value from the third list.
   • To compare a Trial Control variable with a formula, click the double-arrow button and select the operator, then complete the formula in the next list.

Important: Be careful using the operator =. The comparison only takes place when the condition box becomes active. If the variable is updated in other boxes, it may be that this condition box is activated too early or too late. For example, if the condition is met when A = 4 and an Action box sets the value to A = 5 before the condition box is activated, then the condition is never met. Rather use >= or <=.

5. Insert a Comment (optional) and click OK.
6. Insert the Condition box in the appropriate position in the rule. For information on how to insert a Trial Control box, see the EthoVision XT Help.

Creating Conditions Based on a Dependent Variable

1. In the Components pane, under Conditions, double-click the name or click the button next to the dependent variable the condition is based on. For details about dependent variables, see the dependent variables section.

Tip: If you do not see the variable name, click the More button.

Note: The following variables are not available for creating conditions: Acceleration state, Activity state, and behaviors scored with Behavior recognition.

2. In the condition window, under Name, enter a Condition Name. Under Comment (at the bottom), enter a description (optional).
3. Under Condition is met when, from the Statistic list choose the statistic on which the condition is based. See Selecting the Statistic below.
4. Click the Settings button. A window opens with the variable properties.
   • If you track multiple subjects in one arena, see also the Selecting the Subjects section.
   • When finished, click OK in the variable window.
5. From the list next to is:, choose the comparison >=, =, or <= to specify whether the statistic must be greater than, equal to, or smaller than a value x. Enter this value in the box.
   • If you have chosen Current as a Statistic for a discrete variable, choose between true and false. True means the current state must be the one chosen in Settings; False means the current state must not be the one chosen in Settings.
6. Click OK. Insert the Condition box in the appropriate position in the rule. For information on how to do this, see the EthoVision XT Help.

Note: The Body Points tab in the variable properties window is only available if your experiment is set to Nose-point, center-point, and tail-base detection.

Selecting the Statistic

• Current: The value of the variable in the current sample. For example, if a condition based on Velocity is evaluated at sample n, Current is the velocity calculated for sample n. If you want to base the condition on the average velocity from the time of activation of the condition to the current time, choose Mean.
• Total: The total value of the variable (only for continuous variables like Distance or Velocity). This is the sum of all values of the variable up to that time.
• Mean: The mean value of the variable (only for continuous variables like Distance or Velocity) up to that time.
• Minimum, Maximum, Standard Error, Standard Deviation, and Variance: These statistics are normally less obvious to use in a condition. For example, if you select Standard Error for Distance moved, the program calculates the standard error of all distance values calculated between consecutive samples of the track up to that time. The condition is met when the standard error is greater than, equal to, or less than the value specified.
• Frequency: The number of occurrences up to that time. This statistic is available for discrete (state) variables like Movement, and count variables like Rotation and Zone transition. Choosing >= or <= for frequency only makes sense when combined with another condition.
• Cumulative Duration: The cumulative duration of a state from the start of tracking up to that time. You choose the state when clicking the Settings button. This statistic is available for discrete variables.
• Current Duration: The duration the animal has been in a state (for example, in a specific zone or Mobile), taking only the current uninterrupted interval into account. You choose the state when clicking the Settings button. This statistic is available for discrete variables.
• Latency to First: The time from the activation of the condition to the first occurrence of the state of the discrete variable (for example, In the zone becomes true for the variable In zone), or count variables like Rotation or Zone transition. You choose the state when clicking the Settings button.
  • A condition like Latency >= L or Latency <= L does not mean that the condition is met at time L if the first state or occurrence does not occur within that time. The program first calculates when the first state or occurrence occurs, and then compares this with L.
  • Case 1: The subject is already in the zone when the condition becomes active. The condition is never met because the latency of the first In zone state is 0, which is smaller than L.

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