1. An apparatus, comprising: a computing device and a memory, wherein the memory stores a set of computer instructions that, in response to being executed by the computing device, cause the computing device to perform operations comprising: defining at least one first layer for spatial perception, defining at least one second layer for at least partial spatial perception relative to the at least one first layer, causing a first item to be associated with one of the at least one first layer, pursuant to a select action, dynamically causing a second item to be associated with another of the at least one first layer, making the first item and the second item perceptible in sequence, with only one of the first and second items perceptible at a time, so that at least one object in a set of items including the first and second items is perceptible as moving, and creating an imperceptible layer associated with a currently-perceptible one of the first and second items.