We are studying an intelligent perceptual information processing system in which plural processing can run in parallel. Our proposed mathematical Activation-Input-Modulation (AIM) model controls each execution frequency of plural processing independently based on degrees of stimuli detected by external sensors. When external stimuli are detected by some of external sensors, information processing tasks related to the sensors have a priority to be executed, and the stimuli are stored in a memory system. When no external stimulus is detected, the execution frequencies of almost external information processing decrease, and information stored in the memory system is organized by internal information processors. The memory system consists of following three kinds of memories. One is a working memory for storing perceptual information for a few seconds at all times. Another is a short-term memory for storing external information detected as stimuli temporarily. The third is a long-term memory for storing important information permanently. By functions of internal information storing processors and these three kinds of memories, both dynamical and gradual changes can be stored in the memories. The advantage of our proposed method is that resources of a computing machine are made effective use of.