We all perform daily visual searches — distinguishing an object we’re looking for from its surroundings – whether it’s locating our car in a parking lot or picking out one key from among the many items on a desk.
For animals, visual search is often a matter of life and death, from detecting food to spotting predators. Both of us have developed a rapid ability called “pop-out search.”
Until now, most research on pop-out search has focused on monkeys and humans. Israeli scientists, however, have discovered that fish perform pop-out visual searches too, in the same way as mammals. This provides an important insight into the way human vision works.
Writing in Nature Communications, a multidisciplinary team from Ben-Gurion University of the Negev explains its experiments with archer fish, which lack a fully developed visual cortex yet exhibit complex visual hunting behavior by shooting down prey sitting on foliage above the water level.
In their lab, archer fish were able to distinguish between virtual moving targets presented on a computer monitor no matter how many objects were in the display. This is the first evidence for pop-out search mode in a non-mammal or non-primate.
The scientists say this implies that the visual cortex may not be the brain’s crucial component in generating the “map” of unique locations in a visual field. The fact that there is a pop-out search mode in fish may indicate a common, and perhaps even universal, mechanism across vertebrates’ visual systems.