User`s guide

E-Prime User’s Guide
Chapter 1: Introduction
Page 6
a great difference in the appearance of the interfaces. By adhering to Windows standards, E-
Prime has a more familiar look and feel, and will ease the transition from one tool to the other. As
an analogy, MEL Professional can be contrasted with E-Prime in the same way that MS-DOS can
be contrasted with Windows. Windows accomplishes the same basic functions as those
available in MS-DOS, but does so using a graphical interface, with a great deal more ease and
flexibility. Though some of the concepts are the same when moving from MS-DOS to Windows,
one must think differently when working within the Windows interface. Likewise, when comparing
MEL Professional and E-Prime, the packages are similar in that they both allow the creation of
computerized experiments with high precision. However, E-Prime introduces a graphical
interface, and the user must learn to compose experiments using graphical elements, by dragging
and dropping objects to procedural timelines, and specifying properties specific to those objects.
E-Prime offers a more three-dimensional interface than that of MEL Professional. To view
settings within a MEL Professional experiment, the user was required to move through various
pages (i.e., FORMs), and examine the settings in the fields on each of those pages. The FORMs
were displayed in numerical order, but the numbering (supplied by the user) did not necessarily
offer any indication as to the relationships between FORMs or the order in which they were
executed (e.g., TRIAL Form #2 was not necessarily executed second). None of the settings were
applied to the FORMs themselves, and the program would have to be executed in order to see
effects such as a change in font color. Thus, it was difficult for the user to easily identify the
relationships between different events within the experiment (i.e., how FORMs related to each
other), and how specific settings would affect the display.
E-Prime offers a more WYSIWYG (What You See Is What You Get) type of interface, displaying
the hierarchical structure of the experiment and relationships between objects in one location.
There are various methods by which the user may view settings for an object defining a specific
event, and by opening an object in the workspace, the user can see an approximate
representation of what will be displayed during program execution.
The most notable difference between MEL Professional and E-Prime is a conceptual one. E-
Basic, the language underlying E-Prime, is an object-based language that encapsulates both data
and the methods used to manipulate that data into units called objects. MEL Professional used a
proprietary language, the MEL language, which was developed specifically for research purposes
and had no real relationship to existing procedural languages. E-Basic is a more standardized
language, with greater transferability of knowledge when scripting, and greater flexibility to allow
user-written subroutines. E-Basic is almost identical to Visual Basic for Applications, with
additional commands used to address the needs of empirical research. E-Basic is extensible to
allow an experienced programmer to write Windows DLLs to expand E-Prime’s functionality with
C/C++ code. In most cases, however, the need to insert user-written script and the amount of
script required is significantly decreased.
While the direct similarities between MEL Professional and E-Prime are few, users familiar with
MEL Professional and the design of computerized experiments will find that they are able to
transfer a great deal of knowledge when developing experiments using E-Prime. For example,
experience with the structure of experiments and the concept of levels (e.g., Session level, Block
level, etc.), as well as with the organization of data used within the experiment in INSERT
Categories is still very much a part of experiment creation using E-Prime. This experience is not
wasted when moving from MEL Professional to E-Prime, rather it permits the user to more quickly
develop an understanding of E-Prime. The concepts of experiment structure and data
organization remain the same, but the implementation of these concepts within E-Prime has been
greatly improved. In addition to the graphical representation of the hierarchical structure of
events within the experiment, the access of the data used in the experiment has been made
much easier. In E-Prime, data is referenced using the names of attributes in a List object rather
than by referring to an INSERT Category slot number (e.g., E-Prime allows the user to refer to the