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E-Prime User’s Guide
Chapter 1: Introduction
Page 7
“Stimulus” attribute rather than {T1}). Other tasks involving the INSERT Category that are very
cumbersome in MEL Professional are made much easier by the List object in E-Prime, such as
sampling from more than one list on a single trial, sampling multiple times from the same list on a
single trial, and setting different randomization schemes for different sets of data.
To indicate the order of events and maintain timing precision, MEL Professional used the concept
of Event Lists and Event Tables. While quite powerful, Event Tables were difficult to understand,
and required variable locking, which restricted access to variable values until the Event Table
finished executing. E-Prime improves upon the Event List concept with the Procedure object,
which allows users to organize events in a more informative graphical interface, and PreRelease,
which allows the user more control over the setup time required by program statements.
Another similarity between MEL Professional and E-Prime is the range of applications offered to
the user. MEL Professional was a complete tool, offering development, data collection, merging
and analysis applications. Once again, E-Prime offers a variety of applications to provide
comparable functionality, and greatly improves upon the ease of use of these applications. For
example, MEL Professional offered the MERGE program to merge separate data files into a
master file for analysis. E-Prime offers the same functionality with the E-Merge application, but
improves the process by allowing the user to simply select the files to merge and click a single
button to complete the process. As with the development application, all applications within E-
Prime offer a Windows interface, making each more familiar, and easier to use and learn. The
run-time application, E-Run, provides the same time-auditing features that were available to the
MEL Professional user in order to verify the timing of events in the program. With E-Prime,
however, time-auditing occurs more easily, requiring the user only to turn on data logging for a
specific object. E-Prime simplifies data merging and analysis tasks as well, and removes some of
the restrictions enforced by MEL Professional (e.g, MEL Pro collected only integer data). With E-
Prime, all values are logged in the data file as strings, but the Analyze command is able to
interpret the appropriate variable type (e.g., integer, string, etc.) during analysis. In addition, E-
Prime affords compatibility between data files including different ranges for a single variable, or
variables added during different executions of the same program. Even data files collected by
completely different experiments may be merged.
The differences between MEL Professional and E-Prime are too numerous to itemize in this
section. However, based on years of product support for MEL Professional, certain differences
warrant special mention. A major emphasis during the development of E-Prime was concern for
the preservation of data, and data integrity. MEL Professional allowed data for multiple subjects
to be collected into a single data file, which could result in tremendous loss of data if the data file
became corrupted. To safeguard against data loss, E-Prime collects only single subject data
files, and offers the E-Recovery utility in the event that the data file is lost or corrupted. In
addition, the handling of data has been made much easier and more flexible. To accompany this
flexibility, each data file maintains a history of modifications, and security options may be set to
restrict access to certain variables, or to restrict operations on data files. Finally, MEL
Professional users often reported forgetting to log an important measure, and recreating the
randomization sequence to log that measure could be a difficult and lengthy process. To avoid
errors such as this, E-Prime uses the concept of “context”. All data organized in the List object
within E-Prime is automatically entered into the context, and all context variables are logged in
the data file unless logging is specifically disabled.
MEL Professional users will also be thrilled that they are no longer restricted by specific brands of
audio and video cards. While presentation of sounds and images using MEL Professional
depended upon a great deal of information (video card manufacturer, image resolution, color
depth, etc.), the presentation of sounds and images using E-Prime does not require the user to
know anything other than the name and location of the image (*.BMP) files to be presented, or