Introduction to the PDP Simulation Environment - Computational Explorations in Cognitive Neuroscience - page 419

topic, the processing of a single trial itself contains
further levels of sub-processing, which are handled
by yet more processes. Finally, each grain or level
of processing can have associated with it a number
of Statistics which compute values that help you to
understand how the processing is going, how the net-
work is responding, etc. (In addition, miscellaneous
other processes can be attached to a given grain of
overall processing). Now you know why it can be
confusing! Do not panic — you will not have to fully
understand these processes to follow the examples in
the text. However, you will need to know some of the
important buttons that make a given process work,
which are covered in section A.10. Also, when you
construct your own simulations, the project window
contains a graphical view and interface to all the pro-
cesses, making it easier to see what is going on.

from a process in several ways. Most importantly, it
is designed to be executed on an ad hoc basis, and
not as part of the elaborate sequence of processing
orchestrated by the Process objects. In addition, a
Script object doesn't know how to do much of any-
thing until it is associated with a script file ,whichis
just a standard text file containing C++-like code (ac-
tually CSS code, which is the scripting language that
is built into PDP++). The script object just makes it
easier to manage these script files within the project,
and provides a simple graphical interface for running
them. The most important category of script objects
are the Control Scripts with their associated Con-
trol Panel s, that are used for every exercise project
to simplify and automate the execution of the exer-
cise. Please read section A.6 for more information
on these control scripts.

Log(s) The results (i.e., statistics ) from processing are
displayed in Logs , which can also be configured to
send data to a file for later examination. Because the
word Log is also the name of a mathematical func-
tion, the Log object in PDP++ is called the PDPLog .
There is basically just one type of PDPLog, but it can
have several different types of View objects which
display the underlying data in different ways. The
TextLogView just displays the data as rows of text
organized in columns, while the GraphLogView dis-
plays data as line graphs, and the GridLogView dis-
plays data as matrixes (grids) of colored (or shaded)
squares. The NetLogView displays log informa-
tion directly in the network view window. To sim-
plify things, there are trivial subtypes of the PDPLog
object which set the default view type to one of
the above, giving us Te x t L o g 's, GraphLog 's, Grid-
Log 's, and NetLog 's. Each type of log view has its
own set of controls, which are briefly explained in
section A.11, and in more depth where relevant in the
exercises in the text. A given log is typically associ-
ated with a particular level (grain) of process object
(see above), so that it is updated and displays infor-
mation relevant to that level of processing.
Script(s) are somewhat like Processes, in that they au-
tomate routine tasks.

A.4 Buttons and Menu Commands

The exercises will typically ask you to select certain ac-
tions by pressing a button on the overall control panel.
Just press the named button with the left mouse but-
ton to perform that action. Often, the button will bring
up another window where you can fill in more details
about the action you want to perform (e.g., the View
button on the control panel will bring up a window ask-
ing which window you want to view). After specifying
this further information, pressing the Ok button will ac-
tually carry out the action, while Cancel will cancel
the action.
Less frequently, you will be instructed to perform
a menu command in a specific window (not the con-
trol panel window). Each window in PDP++ will typ-
ically have a number of different menu options at the
top of the window. The window in question will ei-
ther be specified by description (e.g., “the project win-
dow”), or as part of the menu specification. Assum-
ing the latter, let's examine the following example:
Project/.specs/Edit/UnitSpec_0 . Each el-
ement or item in the menu specification is separated by
aslash( / ), and the first term (in this case) specifies the
type of window. Once you have located the Project win-
dow, then look for the menu labeled with the next term
( .specs ), and click on it. Then a submenu will appear,

However, a script is different