These afterimages probably represent an overlap in hallucinatory and illusory palinopsia. Illusory palinopsia may be a pathological exaggeration of physiological afterimages. Persistent afterimages produce the appearance of swirling colors. Hallucinatory palinopsia describes afterimages or scenes that are formed, long-lasting, high resolution, and isochromatic. Physiological afterimages appear when viewing a bright stimulus and shifting visual focus. Weapons&colon; Lasers and holographic afterimages. Breese also showed that rivalry occurs between afterimages. Afterimages from lights tend to last longer than the indistinct afterimages from other brightly-colored objects. The remainder of this article refers to physiological afterimages. It is unclear how much of the effect relates to positive afterimages. These green discs are the afterimages of the 12 lilac discs. Afterimages (spectra) appear after a mechanical shock to the eye. Sperling's first publication, "Negative Afterimages Without Prior Positive Images," was in visual psychophysics. Positive afterimages, by contrast, appear the same color as the original image.