can you do color n-back without subvocaclizing?

[Michael Cohn]

I've been doing single n-back with colors and I find that the only way I can remember them at all is to repeat a list to myself in my head, eg, I hear myself saying "green, yellow, green, blue, red" and then updating as each new stimulus comes up. I don't speak aloud when I do this but I can feel my throat moving so I assume I'm subvocalizing at the same time as I'm hearing the words in my head. I can manage 7- or 8-back this way before things start falling out of memory.

I've tried remembering colors without using words, eg, seeing a row of green, yellow, green, blue, and red dots in my head or visualizing the sequence of color in time instead. I find this to take *much* more effort and I doubt I could get above 3-back this way.

Is anyone able to remember strings of colors without repeating them as words? What does it feel/look/sound like in your head when you do it?