creat a fading effect?

[ciccy]

I need to create a gradually fading block of dots/"X"es covering a stimulus and as the dots slowly fade away, the stimulus become visible.

I tried created a transparent animated GIF as attached. But when i input them into Excel, it can't appear simultaneously with the stimulus. So the final effect i had was this gif appearing first afterwhich the stimulus appears. this is my code for the mask:

_mask.gif (400x75)0,.4,03000*~Abused stray cats on street.0,.4,0rt:57*

Any idea how i can get this to work?
Thanks a lot in advance for help! =)

https://email.smu.edu.sg/exchange/xilv.2007/Inbox/RATA%26Thesis/RE%20mask251414.eml/Xmask3.gif/C58EA28C-18C0-4a97-9AF2-036E93DDAFB3/Xmask3.gif?attach=1

[Trevor Newell]

Since DirectRT treats animated .GIF files like video files, you may need to include the stimuli that is underneath with the .GIF.

If willing, it may be worth looking into DirectRT 2010, as the new version allows for transparent image overlays.

Also, the attachment you included can't seem to be accessed. Hm.