Template: Moving Target
Moving Target

Required Experiment Builder Version: 1.5.58 or higher
EyeLink Required: Yes
Type: Complete Example
Difficulty Level: Easy to Intermediate

This example illustrates:
  • How to use Timer trigger and Update Attribute node to update stimulus location
  • How to use Send EyeLink Message node after every time the stimulus changes location for Data Viewer integration

Each trial begins with a target appearing in the center of the screen. After an interval of a duration set in a variable (currently 2000 msec), the target moves in 5 degree steps horizontally in either the left or right direction to a maximum offset of 15 degrees from center. Each movement occurs at the designated pacing interval (again, currently 2000 msec). It then moves in 5 degree steps back to the center position and continues in 5 degree steps in the direction that is opposite its original direction of movement, again to a maximum of a 15 degree offset. Finally it moves in 5 degree steps back to the center position. In summary, the position in degrees of offset from center is 0, 5, 10, 15, 10, 5, 0, -5, -10, -15, -10, -5, 0 (or the sign-opposite version of these offsets for trials with opposite initial directions).

The number of pixels per degree of visual angle can be set by the user in a variable (currently it is set to 28). As the location of the target must be set in pixel coordinates, this value is referenced in determining the location of the target on the screen at each of its positions.

The position of the target is marked with a message at each of its locations so that a trace of its location can be viewed in the 2D Temporal Graph Mode in Data Viewer.

**Additional detailed information about the project is given in the notes section for most nodes. To see notes for a given node, either mouse over that node or click on it to display the notes window. If the notes window is not visible, go to the "View" drop down menu in Experiment Builder, select "Properties", and check "Note".

  1. Download the Moving_Target.ebz example from this message.
  2. Launch the Experiment Builder application.
  3. Unpack the Moving_Target.ebz file to a location on your Experiment Builder PC with "File menu -> Unpack".
  4. Open the project in Experiment Builder.
  5. Deploy the project to a new folder.
  6. Run the Moving_Target.exe from the deployed directory.

.ebz   Moving_Target.ebz (Size: 31.85 KB / Downloads: 35)