Social vs. Nonsocial Housing Differentially Affects Perseverative Behavior in Rats (Ratus norvegicus)

Perseverance, also commonly referred to as grit or industriousness, is the continued effort exerted to complete goal-directed tasks. Many factors, such as stress, can contribute to perseverative behavior, but the role of sociality on perseverance in animal models has not been studied. In this experiment, perseverance was measured in Long-Evans rats; half of which were socially housed (SH) and the other half were nonsocially housed (NSH). Rats were placed in a continuous T-maze; one arm of the maze contained an unobstructed low value reward and the other arm contained a high value reward blocked by a barrier that progressively increased in height across testing sessions. We will hereon refer to the low value reward and high value reward as the low reward and the high reward, respectively. Perseverative behavior was assessed by time spent interacting with the barrier and trials were characterized as either adaptive perseverative trials (high reward obtainment) and maladaptive perseverative trials (low reward obtainment after abandoning attempts to overcome the high reward barrier). SH and NSH rats were equally proficient at overcoming a physical barrier to obtain a higher-valued reward, but the NSH rats spent more time interacting with the barriers during maladaptive perseverative trials than SH rats. NSH rats thus exhibited prolonged efforts to overcome the barrier only to ultimately travel to the low reward option. In contrast, SH rats selected the low reward option earlier in the trial and did not maladaptively perseverate without obtaining the high reward. Putative evidence for increased perseverance in NSH rats is explained in the context of maladaptive perseverative behavior rather than perseverance per se. Increased adaptability and acquisition of task-set in SH rats suggests a role of social housing in advantageous decision making.