Visual and Auditory Presentation Package (VAPP)
Home Page
VAPP is a program that displays visual images and plays pre-recorded sounds on an Intel based personal computer for use in psychological experiments. VAPP was specifically designed for psychological studies such as those used in event-related potential (ERP), functional magnetic resonance imaging (fMRI), positron emission tomography (PET), and psychophysical experiments. VAPP is designed to provide carefully controlled stimulus durations and inter-stimulus intervals (ISIs). The visual images, termed stimuli, are presented on a color monitor or projection system. Auditory stimuli are presented using a standard computer soundboard interface (.wav files). Synchronization codes (called event codes) can be sent out the serial and/or parallel port to signal the onset of presentation for each stimulus for use in signal averaging, measurement of reaction times, or other analytic procedures. VAPP records all information regarding stimulus durations, ISIs, event codes, response codes, and timing information to text based (or comma delimited format - csv) log files. These log files can be easily viewed with a text editor or programs such as MS Excel. VAPP also supports the connection of custom response devices to the serial port for recording patient responses to stimuli.
Written in the "C++" programming language, VAPP runs in an MS-DOS operating system version 6.22 or earlier and is compiled using version 11.0a of the Watcom C++ compiler. VAPP uses the MS-DOS operating system in order to provide precise real-time scheduling of all the presentation parameters (e.g., stimulus durations, ISIs, event-code synchronization). However, a future version of VAPP is planned that will be implemented in Windows NT (see Future Directions for more information).
| The specifications for the stimuli, their durations,
ISIs,
associated codes, and other parameters are contained in a
text-only stim file. The stim file can be created using any
text editor (e.g. VI, Notepad, or Edit), or by a special
purpose program designed for the specific experimental
requirements. Often they are created automatically by the program
SG (Scenario Generator) and/or ADDWORDS; for which
Use and
Reference manuals are available.
VAPP is quite flexible and can be used to present visual and auditory stimuli for a wide range of experiments. Considerable effort was spent attempting to anticipate possible experimental stimulation requirements during its design and development. Some of its features include: |
 |
Simple and straightforward specification of multiple types of images using ASCII text files. (see examples) |
|
Ability to import images from other graphics programs, e.g. Windows Paintbrush. |
|
Ability to employ a standing background image or a solid colored background between and during presentation of stimuli. |
|
Careful control of stimulus timing using multiple video frame buffers. |
|
Fast execution of graphics primitives by virtue of: precompilation of the stim file before presentation, |
|
memory-resident image information, |
|
exploiting extended memory to reduce disk access. |
|
Simple use of sound files (.WAV) - CD quality sampling levels are supported |
|
Wide variety of video cards supported though use of Scitech Display Doctor - See http://www.scitechsoft.com/chiplist/sdd_dos_chiplist.html for a list of supported video cards. |
|
|
For more information contact Kent Kiehl kent.kiehl@yale.edu or Tony Gray (tony_gray@paralynx.com)