You need to raise the gemwin framerate. Just create the object like this: [gemwin 50] and you should see all of the flashes. Also, setting the gemwin to the refresh rate of the display might be best.
Hi,
A friend from our schools psychology department wants to use PD and GEM
for an experiment. Here is his question and attached is the example
patch. We need you help on this. Thanks.
-------------------------------------
OK, this is the patch that I'm going to use to conduct a research on
cross-modal interactions in human perception. I'd be happy to fill
anyone in on the topic because generally human cognition is fun to poke
around.
So the required stimuli are a "beep" sound (which is a 3.5khz sine with
7 ms duration) and a "flash" (which is basically a white circle visible
only for 20ms).
The problem is, it is very hard for an object to "flash" with this short
duration. If you look at the patch you'll see that less than 50% of the
trials do not produce anything.
I have to come up with a workaround to this and I thought maybe if I can
syncronize the onset of the flash with the refreshing rate, I can at
least make the disk visible for all of the trials. I can sacrifice the
precision in terms of duration but that is bound to happen I guess.
I made this patch on windows with my laptop with a poor refreshing rate
and another laptop with Macosx did not perform any better on the
task(they are both 60hz screens). But I am guessing that a non-lcd
monitor may do better? Any comments or suggestions on this?
Relevant information on the stimuli and the procedure can be found in
this reference article for those of you who are interested "Visual
illusion induced by sound" by Ladan Shamsa, Yukiyasu Kamitanib, Shinsuke
Shimojoa.
#N canvas 78 53 295 395 10;
#X obj 13 248 gemhead;
#X msg 101 259 0 0 0;
#X obj 13 311 disk 3 40;
#X msg 72 173 255 255 255;
#X obj 72 147 bng 15 250 50 0 empty empty empty 0 -6 0 8 -262144 -1
-1;
#X text 158 232 problem number;
#X obj 72 200 t b l;
#X obj 20 30 cnv 15 100 60 empty empty empty 20 12 0 14 -195568 -66577
0;
#N canvas 0 22 454 304 gemwin 0;
#X obj 132 136 gemwin;
#X obj 67 89 outlet;
#X obj 67 10 inlet;
#X obj 67 41 route create;
#X msg 67 70 set destroy;
#X msg 142 68 set create;
#X msg 198 112 destroy;
#X msg 132 112 create \, 1;
#X connect 2 0 3 0;
#X connect 3 0 4 0;
#X connect 3 0 7 0;
#X connect 3 1 5 0;
#X connect 3 1 6 0;
#X connect 4 0 1 0;
#X connect 5 0 1 0;
#X connect 6 0 0 0;
#X connect 7 0 0 0;
#X restore 25 69 pd gemwin;
#X msg 25 50 create;
#X text 21 29 Create window:;
#X obj 101 233 delay 20;
#X obj 13 284 color 0 0 0;
#X connect 0 0 12 0;
#X connect 1 0 12 1;
#X connect 3 0 6 0;
#X connect 4 0 3 0;
#X connect 6 0 11 0;
#X connect 6 1 12 1;
#X connect 8 0 9 0;
#X connect 9 0 8 0;
#X connect 11 0 1 0;
#X connect 12 0 2 0;
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