How to set opacity after clicking on the stimulus?

Hi all,

What I’m trying to do?
It is a simple task that will appear one stimulus in the middle of the screen. After that the participant need to click on it to more four stimulus appear each one in each side of the screen. And then choose one of them.

What I specifically need?
After the chosen stimulus, I want its disappear.

Here is the spreadsheet:

Here all the images are setted in the builder

And then I need a code to insert here

The ideia is four trials (sequential as I setted in the spreadsheet).
One of the things I was thinking is to change the opacity of the clicked stimulus. I dont know for sure, anyone suggest something?

SMTS.psyexp (153.4 KB)