This article applies to:
E-Prime Extensions for EyeLink 3.0
The EyeLink PackageFile routine EyeLink_SetDisplayObject is useful when greater customization of display stimuli is needed than what ELTrialBegin provides. SetDisplayObject replaces the display objects provided by ELTrialBegin. The resource files are stored in the Output > Resources folder.
The first required parameter to this routine is c which is the experiment context.
The second required parameter is strSource. This is the name of the object to be shown in Data Viewer playback (e.g. Stimulus", "Stimulus.IA", etc.)
The third parameter is vMode. This optional parameter allows you to change the mode of capture on the object. The options are "composite", "object", "fullscreen", and "alternate".
- Composite is used by default and is a combination of everything shown on the display. Composite breaks down each component into its own resource file. These files can be reused between trials and experiment sessions.
- Object provides a display representation of an individual component.
- Fullscreen provides a display representation of the full screen.
- Alternate must have the vAlternate parameter specified to provide additional options to define the display object (see below).
The fourth parameter is optional and is vResourceName. It is a parameter that specifies the name of the resource saved to disk and used for playback in DataViewer when the mode is not composite. By default, the resource name is automatically generated and given a unique name. We recommend providing a resource name when not using composite to avoid unnecessary creation of files in the Resources folder.
The fifth parameter is vAlternate. This is an optional parameter that specifies the name of the alternate resource to be used in Data Viewer. If specifying "alternate" for vMode, you must set an alternate resource to be used. This parameter is ignored for any other mode besides "alternate". When the value for vAlternate represents a file on disk, the file is used for the display object. Otherwise the literal text is created for the display object representation.
The sixth parameter is vDelay. it is an optional parameter to delay when the display object is shown in Data Viewer. The delay is the amount of time from when the object is displayed on-screen.
EXAMPLE: This example uses a modified version of ELFixedPositionIA.es3. The EyeLink_SetDisplayObject routine is added after ELTrialBegin. The TrialList contains the values for some of the parameters in the SetDisplayObject routine. Running through the experiment in sequential order allows you to examine how the various modes save the display by looking at the images in the Output > Resources folder after the run. Note that "composite" mode saves "auto" images.
After you run through the experiment, open the .edf in Data Viewer and examine the playback per trial. It may help to also have the images from the Resource folder visible to match them per trial.