Black Box IEEE 1284 Podręcznik Użytkownika Pobierz pdf (Strona 73)

The Black Box Toolkit Page 73 of 98

The BBTK DSCAR (Digital Stimulus Capture And Response) software was programmed to

act as a virtual human with the following characteristics:

1. Watch for a visual event on line 3 (the opto-detector)

2. After detecting the leading edge of a visual event wait 300ms (about average for a

human subject)

3. Generate a key down event (switch closure) on line 7 that lasts for 150ms (about

average for a human subject)

The actual DSCAR sequence can be seen below. Note that a total of 16 visual events are

being “watched” for. This sequence will work for any device that makes use of a switch

closure, i.e. mice, keyboard, button box. Details on the sequence for activating the voice

key are given later.

The DSCAR sequence is pretty straightforward. We only wish to make one kind of

response. That is, a switch closure on line 7 with a “key down” duration of 150ms. This is

shown in the upper “BSR” spreadsheet. In this case we are only making use of one

response on several occasions from a bank of 32,000 possible responses.

Next in the lower sheet we have added 16 event patterns to watch for in the “SPM”

spreadsheet. For each event we have told DSCAR to wait for 300 milliseconds after

detecting the leading edge of an event on line 3. Once detected, the predefined response

will be generated. In this case the response is a switch closure on line 7. This will have the

effect of pressing the left mouse button at exactly 300 milliseconds after the image

appears and holding it down for 150ms. One would therefore reasonably expect the

paradigm to record a response time of 300 milliseconds.

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Black Box IEEE 1284 Podręcznik Użytkownika Strona 73