In DMDX there are specific terms that refer to unique DMDX things, I'll attempt to enumerate them here.
Run. When DMDX is told to execute a script we refer to it as running an item file.
Switches. Switches are options that occur in items (as opposed to
the parameter line) and are normally only active for the frame the switch
occurs in as distinct from parameters that are active for the whole item file -- however there are switches that are also parameters depending on whether they are used in a frame or the parameter line.
Sometimes a switch will refer to the old DM/DMTG
single character options as
opposed to the DMDX keyword options that are angle bracket delimited words
with optional arguments.
Text segment. A text segment occurs between double quotes in a frame of an item. There can only be one text segment in a frame
(more double quotes can occur in a keyword's arguments however). A text segment can also be used as a file name if certain switches are present in an item.
Tic. Alternative spelling of Tick (below).
Sometimes I use tic and other times I use tick, sorry.Tick. A tick is a retrace interval (the time between one vertical
retrace and the next) or the time to refresh the display once. On a 60 Hz display this
is 1/60th of a second or 16.666 milliseconds and most displays are 60 Hz
ones. If you don't know what your display's refresh rate is you can
use TimeDX's Refresh Rate test. Times of displays in
DMDX are usually specified in ticks because in the past all displays had
to be some integer number of ticks (largely to keep monitors from blowing
up and so forth), prior to the
freesync video mode
modifier there was no way to present a display for a fraction of a tick.
Clock On. The command to start gathering an RT in DMDX is referred
to as a "clock on".
Correct Response indicator.
Indicates which response within an item is the correct one.
Short for correct response indicator (above).
Item. An item is one display sequence
that normally gathers one reaction from a subject. Items occur following the parameters in an item file. The only unique thing differentiating one item from the next is the semi-colon at an item's end. Semi-colons are only usable as item delimiters, they can never be displayed or used for anything else. An item usually consists of a
correct response indicator, an item number and a series of frames, if not
it's just one frame.
Item File. An item file is a file that contains the script DMDX is going to follow
and it is a Rich Text File (so it has a .RTF file extension). It consists of two things, parameters and items.
- Item number. Items have
numbers both to identify the
response in the output file and also to indicate the item type
(instructions that don't gather RTs for instance have an item number of
- Frame. A frame in an item is one display element. Normally frames are presented in a timewise sequence however they can be presented simultaneously. A frame can contain switches and an optional text segment. Frames are
delimited by forward slashes (/)
- Parameter. In the first section of an item file parameters are listed. In old item files the parameters were limited to the
first line of the item file, nowadays an
extended parameter line is possible. Parameters are active for the entire run.
- Refresh Interval. The time between one refresh of the screen and
the next, also referred to as a tick (see below).
- RT. Reaction Time, usually the time
the subject takes to respond to a stimulus.