An empirical study on the motivation of helping behavior in rodents

Helping behavior is universal across species. In recent years, it has become a new trend for scholars to use rodent models to explore the motivation of helping behavior. Empathy, relieving personal distress, and desire for social contacts are plausible motivations for rodents to help, but debates exist about whether helping behavior is inspired by one of the motives or the combination of them. In this study, to explore the motivation of helping behavior in rodents, the two-chamber experimental apparatus designed by Carvalheiro et al. (2019) was improved by adding an intermediate chamber to manipulate the possibility of the free rat's social contact with the entrapped rats after implementing the helping behavior as well as the possibility of the free rat's escaping from the helping context to relieve its personal distress in the process of helping decision-making. Male Sprague-Dawley rats (N=108) were used as subjects in three experiments. The latency to open the door for helping the entrapped rat escape was recorded as the main outcome variable.Experiment 1 confirmed the existence of helping behavior and the impact of social contact on helping behavior under the condition of being unable to escape from the helping context, using a 2 (possibility of social contact: yes/no) by 4 (restrainer condition: empty restrainer, familiar rat, unfamiliar rat, toy rat) mixed experimental design. The results showed that when social contact was allowed, the free rat maintained a consistently short latency to help, but when social contact was not allowed, the free rat's latency to help became longer and longer as sessions went on until the free rat no longer helped at all within the 15min session limit.Experiment 2 explored the impact of social contact on helping behavior under the condition of being able to escape from the helping context, using the same experimental design as Study 1 but keeping the door between the middle chamber and the dark chamber open. The results showed that the existence of the dark chamber was beneficial for the non-social contact group to help continuously, but extended the latency to help in the social contact group, namely, relieving personal distress contributes to the emergence of helping behavior, but the emergence of helping behavior ultimately depends on whether social contact could be made.Experiment 3 explored the influence of previous social contact experience and current social contact possibility on helping behavior under the condition of the free rats' having been trapped before, using a 2(possibility of social contact: yes/no) by 2 (previous social contact experience: yes/no) by 4 (restrainer conditions: empty restrainer, familiar rat, unfamiliar rat, toy rat) mixed experimental design. The results showed that previous experiences of being trapped did not affect helping behavior, but previous experiences of social contact were conducive to maintaining continuous helping behavior in the non-social contact group.In summary, the following conclusions were obtained through this study: (1) desires for social contact and the pursuit of interesting environment are important motivations for rodents' helping behavior, regardless of the possibility to escape from the helping context. (2) Relieving personal distress can help sustain helping behavior, but the emergence of helping behavior ultimately depends on whether social contact can be carried out after helping. (3) Previous experiences of social contact rather than the experiences of having been trapped contribute to the occurrence of helping behavior. (4) Empathy may not be the main reason to maintain helping behavior but rather can be used to describe the process of helping behavior.This study extends the comparative research on the motivation of helping behavior and provides some hints for the psychological development and educational practices in humans.