A five‐channel LED display to investigate UV perception

Abstract

Abstract The ability to see ultraviolet (UV) light (<400 nm) may have importance for foraging, communication or navigation in many taxa including insects, crustaceans, fishes, amphibians, reptiles, birds and mammals. Behavioural experiments reveal how vision mediates such behaviour; however, our knowledge of UV perception is constrained by the challenge of creating and calibrating stimuli that reflect or emit UV. Commonly used technologies for displaying visual stimuli—such as computer screens and printers—are designed for human vision and thus are unsuitable for testing UV perception. To overcome this limitation, we designed and constructed a display with five spectral channels with peak wavelengths as follows: red at 629 nm, green at 526 nm, blue at 466 nm, violet at 395 nm and UV at 367 nm. Each pixel of the display consists of five LEDs with a baffle to prevent crosstalk from adjacent pixels and a diffuser to promote uniform colour mixing. The LEDs are driven by high‐performance pulse‐width‐modulated constant‐current drivers with a maximum flicker rate of 64 kHz and a maximum frame rate of 6.5 kHz. This method allows colour mixing with wavelengths as low as 350 nm to be calibrated and tested rapidly and concurrently. To demonstrate the utility of this display, we conducted colour detection tests using the anemonefish, Amphiprion ocellaris, a species known to have UV‐sensitive cones. Fish were able to associate pecking all target colours (‘Blue’, ‘UV‐grey’ and ‘UV’) with a food reward, demonstrating for the first time, UV perception in A. ocellaris. The RGB‐V‐UV LED display is a useful device for behavioural tests of colour vision across a broad spectrum (350–650 nm) visible to many animals and can be used to investigate various questions concerning animal perception, including colour discrimination and categorisation. We include design documents and source code so this system can be further developed and modified to investigate other visual behaviours in a variety of taxa.