In what stage of memory do images vanish unless they are focused upon?

The correct choice refers to sensory memory, which is the initial stage of memory where information is briefly held in its raw sensory form. In sensory memory, visual images and other sensory inputs are retained for a very short duration—typically less than a second for visual stimuli. If attention is not directed toward these images, they quickly fade away and are not transferred to further stages of memory. This fleeting existence highlights the function of sensory memory as a temporary storage system that captures stimuli from the environment, but does not hold them long enough to develop them into more enduring memories.

In contrast, short-term memory holds information for a longer period than sensory memory, often around 20 to 30 seconds, and allows for the manipulation of that information. Long-term memory has a potentially limitless capacity and duration, where information can be stored indefinitely. Working memory is a more complex system that not only holds information but also processes it through mental manipulation. Each of these other types of memory serves a different function, but none operate in the same immediate, fleeting fashion as sensory memory.