input to canvas

[Mich]

Hello Wendy,

Wednesday, July 5, 2006, 10:52:25 AM, you wrote:

WD> Hi
WD> I was hoping someone could give me some advice about using the canvas 
WD> object.

WD> I have designed an experiment in which a dot moves along the screen (using a
WD> copy from off-screen canvas at refresh) and I need to add input to it.
WD> Basically, the subject must press the keyboard to indicate if the dot is the
WD> same or different as before.

WD> Does anyone know if it is possible to add input to a canvas object?

It is, but it's difficult to implement, so should you still wish to
use Eprime instead of going for visual basic, I'd suggest trying the
following trick:
add a textdisplay of 0 ms just prior to the canvas and set the time
limit to something like 2000 ms. That way, you can use all the logging
of the textdisplay instead of adding all that using inline (and with
the maximum inline being what it is...). I've also done this and it
works well enough, but you might consider logging your own reaction
time instead of using the text display's response. Just set a
clock.read at the first inline and subtract this from the RTTime.

Let me know if you need any further help!

Cheers,

Michiel Spapé
Leiden University