# Distance to point

Definition

The shortest distance between a subject's body point and one or more points.

The calculation of this variable is performed in two steps:

1.The coordinates of the defined point(s) and the body point(s) for the current sample are found.

2.The distance in a straight line between the coordinates is calculated.

If your experiment is set to Only center-point detection or Color marker tracking, the body point options are not available. Calculations are based on the center point.

How to specify Distance to point

1.Click the Add button next to Distance to point and click the Distance to point tab.

2.Under To following points, select the points you want to consider for the calculation. For example, if you want to calculate the mean distance to Cue 1, select Cue 1. By default, Arena (that is, the center of the Arena) is selected.

If you have chosen two or more points, select how the points should be analyzed:

▪For each of the selected points: Points are analyzed separately.

▪Shortest distance to any points: For each sample, EthoVision XT chooses the point that is currently closest to the body point(s) you have chosen, and uses the resulting distances for calculating the statistics.

3.Under From following body points, select the points you want to consider for the calculation. For example, select Nose-point if you want to analyze the distance between the nose-point and a specific point. By default, Center-point is selected.

If you have chosen two or more body points, select one of the following from the list:

▪For each of the selected points: Statistics are calculated for each point separately.

▪Shortest distance to any point: For each sample, EthoVision XT chooses the body point that is currently closest to the point, and uses the resulting distances for calculating the statistics.

4.Complete the procedure to add the variable. See Calculate statistics: procedure.

Notes

▪If your experiment is set to Only center-point detection or Color marker tracking, the body point options are not available. Calculations are based on the center-point.

▪The center point of a zone can lie outside the zone itself. This occurs when the zone is ring-shaped or very asymmetrical.

Applications

Below are two examples of how Distance to point is of particular use in studies of spatial orientation:

▪When analyzing the flight behavior of an insect in an odor plume, the plume itself can be defined as a zone, while the upwind odor source is regarded as a point. Using Distance to point, you can measure the insect’s progress towards the source at any moment in time.

▪In an open field test, using the center point of the central area of the arena, Distance to point can be used to measure how far the animal ventured into the central area.