Desire for social contact, not empathy, may explain "rescue" behavior in rats

Ben-Ami Bartal et al. (Science 334:1427-1430, 2011) showed that a rat in an open space (free rat) would touch the front door of a restraining tube to open its rear door, thereby enabling a rat trapped within (trapped rat) to enter a larger space that was farther away from the free rat. Since opening the rear door distanced the trapped rat from the free rat, Ben-Ami Bartal et al. argued free-rat behavior could not be motivated by the pursuit of social contact. Instead, this rat was empathically motivated, its goal being to reduce the presumed distress of the rat trapped in the restraining tube. In two experiments, we show that (a) a free rat will not learn to touch the front door to open the rear door when it is the first condition of the experiment; (b) over time, a trapped rat will often return to a restraining tube despite its presumed aversiveness; and (c) a free rat experienced in touching the front door will continue to touch it even if touching does not free the trapped rat. We explain these results and Ben-Ami Bartal et al.'s in terms of two processes, neophobia and the pursuit of social contact. When first placed in a restraining tube, neophobia causes the trapped rat to escape the tube when the rear door is opened. Across sessions, neophobia diminishes, permitting the rats' pursuit of social contact to emerge and dominate free- and trapped-rat behavior.