Which of these slider handles have the most affordance?

Question

Working on a filter for desktop, and need to decide which kind of filter handle giveS the user the obvious impression that they can use it as a slider.

Any other suggestions besides the above are welcome as well.

Answer 1

Combine 1+2 with a little bit of seasoning.

Option 2 is great because the selected range is thicker and a bit darker. But the black handles don't provide any affordance. So I would replace them with circular handles from Option 1, but why not throw in a bit of drop shadow for that extra-affordance?

Answer 2

Without knowing much of the context or output, I'd say four initial things:

• remember the affordance in context (is it to be manipulated by mouse or finger, or both, and which of these better indicate that/both of those interactions?)
• similarly, remember the affordance must be 'visible' in the context of use (straight up, regardless of device, 4 and 1 throw up 'visibility' flags because of colour and sizing.)
• what are people used to? (for the output, in similar interactions, in similar contexts, etc)
• What can there be as a failsafe? Text input? (Sliders and Accessibility: Usability of sliders for users with disabilities)

And then test!