Binocular stimuli
-----------------

The general parameters that are used to set and control binocular
stimuli are described below.  Most visual stimuli will default to
monocular presentation to the left eye unless appropriate parameters
are set.

To specify a binocular stimulus, set::

  stim_form 3d_b

This specifies that the stimulus will have a binocular representation,
that is, two separate 3D image arrays (one for the left and one for
the right eye) may be used.  This has been implemented for the following
``stim_type`` values,

* sine
* randot_stereogram
* barnoise

When ``stim_form`` is set to "3d_b", the following parameter can be
set to allow only the left or right eye to receive its component of
the stimulus::

  stim_monocular right    # "right", "left", "both"

In this case, the normal right eye stimulus is presented whereas the
left eye stimulus is set to a blank field at the background color.
The value of ``stim_monocular`` defaults to "both", so that both eyes
will receive the intended stimulus if this parameter is not specified
in the .stm file.