Activity time for diet-restricted Japanese macaques is manipulated using a Chow Tracking feeding method

This study investigates the effectiveness of the Chow Tracking feeding method, which is based on psychoacoustic threshold tracking used to obtain stable sensory thresholds. Diet-restricted Japanese macaques were permitted a 10-minute Activity Time prior to performing in daily psychoacoustic experiments, allowing them to interact with their environment and conspecifics before entering a restraint chair on their own. Participants received an increase, decrease, or no change in post-experiment feeding based on how much Activity Time was used for the given day. The monkey's ration increased if he had an Activity Time < 4 minutes (indicating hunger), remained constant if he had an Activity Time 4-6 minutes (ideal zone), and decreased if he had Activity Time > 6 minutes (indicating satiation). Activity Time was significantly changed by Chow Tracking from Baseline (ranging 3.7-10 minutes, M = 5.6 minutes) to Stage 1 (ranging 3.8-9.0 minutes, M = 6.0 minutes) and Stage 2 (ranging 3.6-5.6 minutes, M = 4.3 minutes). Additionally, Chow Tracking resulted in an increase in food ration and weights. This study also demonstrates a significant relationship between hunger and Activity Time. As the time interval between morning feeding and experiment start time increases Activity Time decreases, indicating that the hungrier a monkey is the more motivated he will be to enter the restraint chair.