Logfiles

Logfiles contain information about events that occurred during a scenario. When running an experiment, logfiles are written to disk when a scenario ends unless the no_logfile header parameter is true. If you are running a scenario directly from the editor, Presentation does not create logfiles. The logfile can contain three separate tables of timing information for events that occurred during the scenario: the event table, the stimulus table, and the video table. The first table in the logfile contains the same information in the same format as the default event table in the Analysis window, except that times are given in tenths of milliseconds instead of milliseconds. The logfile will also contain the name of the scenario taken from the scenario header parameter and the time and date of the system clock when the logfile was written. You may optionally insert text into the logfile that describes the experiment or details about the subject. The settings for what to insert into the file can be found on the Logfiles panel.

Logfiles are written in plain text. The columns of all tables are delimited by a character chosen on the Logfiles panel. You can import the logfile into Excel or other spreadsheet programs by opening the file and specifying the delimiting character.

Logfiles are placed in the logfile directory. You can select this directory on the Scenarios tab.

As mentioned above, logfiles are written to disk when a scenario ends unless the no_logfile header parameter is true. In some cases, like for very long scenarios during which you don't want to risk losing data should anything disastrous happen before the end, you may wish to save logfiles earlier than the end of the scenario. If you wish to save logfiles early, you can use the scenario_logfile::save PCL method. For SDL-only scenarios, you can use a save_logfile object. A save_logfile object is a special stimulus object that is not truly a stimulus, but within Presentation it functions like other stimuli. You specify timing in the same way, and you may associate event codes and port codes with the event. The effect is to save a logfile containing all the events up to the save_logfile event.

The following sections give more details about logfiles.