touch: if palm on screen, then no touch registered

Hi,
If the monkey places his entire palm on the touchscreen, then no touches are registered. But if he places a few fingers, then they are registered.
This does not seem to be an issue with the touchscreen itself - i.e., it works even with palms on, outside of ML2. Do you know if this might be due to something in Monkey Logic?
Thanks,
Lucas

Palm rejection is not a function of touchscreens but a software process of Windows. It is disabled in NIMH ML, since it introduces delays.

I see - thanks for the info

In some cases I would prefer palm rejection even if there is delay.
Is there a straightforward way for me to turn this back on?

No.

I might misunderstand your question. Are you saying that your subject touches a target with his entire palm? Or does he place the palm of one hand on the screen and use the other hand to point?

He places the palms of both hands on the screen. I want him to keep his hands off the screen. The main point is that I would like to be able to detect that this is occuring, so that I can have the task respond appropriately (e..g, by imposing a timeout, or reduced rewards). However, the problem is that when his palm is on the screen, no touches are registered at all.

A simple solution is I could detect this behavior as touches at multiple positions on the screen.

Does this make sense?

Does your touchscreen support multi-touch?

So do you not see a hand icon on the corresponding location of the control screen, when the subject places its palm on the subject screen (i.e., touchscreen)?

It is typical to train them to take off their hands from the screen to initiate a trial. The following function may be useful for that purpose.
https://monkeylogic.nimh.nih.gov/docs_RuntimeFunctions.html#istouching

Yes it does. The problem is that if the entire palm is on the screen, then there is no hand icon on the screen at all, and the touch analogdata is filled with nans.

Indeed, my goal is to train them to keep hands off. This works fine for other animals, since the multitouch works well for detecting multiple fingertips.

If you can reproduce the situation, put a palm at one corner of the screen and touch the opposite corner with the other hand. Then see if the touch is still not registered.

I do not know how your subject places its palm, but, if the palm is too close to the touched point or blocks either X or Y direction of it, the touch may not be detected.

Yes I am able to reproduce the error.
In fact you are correct - if I place my palm on one corner, I am able to touch with a finger on the opposite corner. But my touches close to the palm do not register.
There seems to be a no-touch zone surrounding the palm, with radius about 2/3 screen size.
It does not seem to be due to overlap of XY locations.
Do you have any suggestions?

Restrain one arm of your subject.