Jeff Raven's grin altered imperceptibly.

With great majesty, the scene was imperceptibly altering as the planet swung toward the dusk line.

One leak prevention technique involved an intelligence trick he called "the old canary trap," in which he imperceptibly altered each document given to clients as a way to identify those who leaked a report.

The plot of the novel continues to unfold in its pattern of liberty, capture and escape, with the protagonist's goal imperceptibly altering from rejoining his outer world comrades to romance with La-ja.

'Hello,' Raven returned, his grin altering imperceptibly.

The timbre of his voice altered almost imperceptibly.

The day's length altered imperceptibly as Earth exchanged momentum with her moon.