Interactions in swarm robotic search are explored for intelligence emergence based on Extended Particle Swarm Optimization (EPSO) model. For this end, the best combination of proper properties in typical versions of PSO is transferred to swarm robotic search. Synchronous / asynchronous communication modes and respective control strategies under conditions of parallel distributed control are comparatively studied by simulations. The results showed that the asynchronous communication mode predominates over its synchronous opponent in efficiency.