Evidence that anuran foot flagging displays function to exploit perceptual systems that mediate predator recognition

Animal perceptual systems can shape the evolution of communication signals that help individuals negotiate social interactions. Here, we study this concept by exploring how conserved object recognition systems in anuran amphibians relate to evolutionary innovations in visual signaling behavior. We focus specifically on Bornean rock frogs (Staurois parvus), given that males of this species wave at each other with their hindlimbs (foot flag) to compete for access to mates. Past work shows that males who see this signal freeze as though they saw a predator; thus, we test whether perceptual systems that help frogs and toads detect and respond to looming threats are intertwined with mechanisms that govern sexual competition. We find that this is likely the case, as visual activation of cognitive systems for predator detection trigger the output of behavior that typically mediates sexual competition, as well as hints of antipredator behavior (freezing and avoidance). When we visually activate these same cognitive systems for predator detection in anuran species that do not foot flag, we find no evidence of aggression-rather, these individuals simply produce canonical antipredator reactions. Altogether, these findings suggest that the perceptual systems for threat detection in foot flagging S. parvus are likely intertwined with the cognitive systems that underlie sexual competition. These results illuminate the way perceptual systems might drive signal innovations, potentially giving rise to bizarre displays that are otherwise difficult to explain. (PsycInfo Database Record (c) 2026 APA, all rights reserved).