What do we call the visual effect that remains after a stimulus has been removed?

The term for the visual effect that remains after a stimulus has been removed is "after images." After images occur as a result of the overstimulation of photoreceptors in the retina. When you look at a bright light or a specific color and then shift your gaze to a neutral surface, the visual system continues to process the removed stimulus due to the lingering activation of the photoreceptors that were stimulated by the initial image. This phenomenon illustrates important aspects of visual perception and how sensory receptors can have lasting effects, leading to the persistence of visual experience even after the original stimulus is gone.

The other terms, such as visual echoes, perceptual remnants, and fleeting images, are not standard terminology in the context of visual perception and afterimages, making "after images" the recognized and accurate term used in neuroscience to describe this phenomenon.