[arjie]

That's a subset of the objective. The objective is to detect all humans because they wouldn't spot the 'face' in the coloured circles. Whether or not it's coloured doesn't change that.

Unless you're concerned about the rights of colour-blind computers for some reason.

[pimlottc]

Ha, oops, I guess I didn't read it closely enough. As someone who's partially colorblind, just seeing those dot patterns pisses me off... :P