To that point, when I do the picture captcha (Select the crosswalks type question), I always click a square I know is not valid and then de-select it. Adds some "human-ness" to the interaction and I never get a 2nd challenge that way. Will that be the future? Look for behavior that is too perfect?
I feel like Captcha already takes into account of how quickly I select the pictures already. If I spend the time to get it perfect, I end up with more challenges than if I just select quickly based on my instincts.
If you assume that most humans spend the minimum effort possible on their captchas, your gut response is also more in line with other responses than your well thought-out response. Even a matching based on the selected squares would pick up on this.
