This a prototype of a "VGA switch", a device I designed and built to switch a
VGA-signal on and off very fast and at the same time it measures a "responsetime".
It's purpose is to measure the responsetime very precisely during SART.
(Sustained Attention to Response Test)
In the test, participants view a computer monitor on which a random series of single
digits are presented at the regular rate of 1 per 1.15 seconds. The task is to press
a single response key following each presentation with the exception of a no-go digit,
to which no response should be made.
The repetitive and unselective responding for 89 percent of presentations was designed
to lull participants into a rather absentminded "stimulus-press-stimulus-press"
mode--a tendency that they should aim to resist if they are to avoid to inadvertently
responding on the rare and unpredictable no-go trials.
The circuit contains (among other things) two analog VGA-buffers/switches,
a PIC-microcontroller and an RS-232 interface.
- 2 VGA outputs, one switchable via RS-232
- 3 inputs for response buttons
- marker output
- event output
- event time: 1 to 65534 videoframes
- responsetime measuring resolution: 25.6 microseconds
- results are send to a computer via the serial port
