In the context, they mean the same thing. I like the image of nictate, but naggingly over-question higher register words in my writing all the time. In the scene, a male of an alien species who is tiny compared to the female (think hedgehog size compared to a human, but still looking like the female), walks across the expanse of a control dashboard on the deck of a female commander's ship. The male has a membrane across the top of his head instead of a complete skull that pulls back to expose his brain, which he then sticks into a correspondingly shaped depression in the dash, delivers the data he holds in his brain, and then dies, brushed aside by the female down an adjacent slope into a disposal chute. It's a way to deliver private secure messages. So, back to the question: the brain flap. I like the quick action, the speed, implied by nictate, but I worry that it's overly "look at my big word!" compared to just peel or pull back. Thoughts?