This article applies to:
This item was introduced in E-Prime 2.0 (188.8.131.52).
When designing an experiment, the use of a specific drive and/or directory (i.e. C:\Experiment\image.bmp) is typically discouraged. Instead, PST recommends placing the files in the same directory as the experiment. This way, only the file name and its extension (e.g. "filename.wav") must be specified, with no path or drive information in the E-Studio interface. If the files are not saved in the same folder as the .es or .ebs file, the experiment won't be able to access them at runtime and an error may occur.
Due to string parsing within the software, E-Objects should utilize the forward-slash character ( / ) as opposed to the backward-slash ( \ ) to separate file paths.
In general, we always recommend the use of relative paths instead of absolute paths. Any image or movie files that are loaded by the experiment should be placed in either the same folder as the experiment folder or in a sub-folder. If folder information is included in the relative path, then the forward slash character ( / ) should be used rather than the backslash ( \ ).
NOTE: Objects with filename properties will attempt to convert any \ or \\ character to / forward slash to assist with escape character issues using the \\ key sequence.
INFO: Organization of experiment resource files 
Legacy End User Comments
|Explanation: Following a widespread computing standard, in many places E-Prime uses the backslash character "\" as an "escape" character that can change the meaning of the next character, and to avoid this one must enter a double backslash in order to escape the escape character. When entering file names into the E-Studio GUI, E-Studio typically generates code with each backslash character translated into double backslashes for you. But if you put a backslash before a left square bracket, e.g., "stimuli\[ImageFile].bmp", then E-Studio fails to treat the "[" as introducing an attribute reference and may produce a mystifying compile-time error message.
Following the rule stated just above, you may avoid this by using double backslashes. As it happens, E-Prime, and much of Windows, also allow a forward slash as a path separator. Using a forward slash for a path separator (instead of double backslashes) conforms better with widespread computer standards used outside Windows, and seems less clumsy and more readable.
All that said, it turns out that the latest version of the E-Studio GUI (184.108.40.2063 as I write this) automatically and silently translates your backslashes in filename entries into single forward slashes, so then none of this matters any more.
TLDR: If you use an older version of E-Prime, just use single forward slashes instead of any backslashes in file name entries, as the main topic text says. If you use a more recent version, you may not have to think about any of this anymore.