Pinning in the play fighting of rats: a comparative perspective with methodological recommendations

Thumbnail Image
Himmler, Stephanie M.
Himmler, Brett T.
Stryjek, Rafal
Modlinska, Klaudia
Pisula, Wojciech
Pellis, Sergio M.
Journal Title
Journal ISSN
Volume Title
eScholarship Publishing, University of California
During play fighting, rats attack and defend the nape of the neck and during the course of this competitive interaction, they may adopt a configuration in which one animal stands over its supine partner (i.e., pin). Because the pin configuration is typically frequent and relatively easy to identify, it has been widely used as a marker to detect the effects of experimental treatments. In the present study, the frequency of pinning during standardized, 10-min trials in three strains of rats, Long Evans hooded (LE), Sprague-Dawley (SD) and wild (WWCPS), was compared. LE and SD had higher rates than WWCPS rats (#/min: 6.5, 5.5, 1.5, respectively). When adjusted for strain differences in the frequency of attacks, SD as well as WWCPS rats had lower rates of pinning compared to LE rats. Both SD and WWCPS rats were less likely to use tactics of defense that promote pinning. Moreover, while the majority of the pins achieved in LE rats arose from the defender actively rolling over onto its back, the majority of pins in WWCPS rats arose because one partner pushed the other onto its back. SD rats were intermediate in this regard. Finally, once they do adopt the pin configuration, SD rats are less likely to remain supine than LE and WWCPS rats. That is, both SD and WWCPS rats have significantly fewer pins than LE rats, but a different combination of factors account for this. These data highlight the need to use a battery of measures for ascertaining the effects of experimental manipulations on play. Some suggested guidelines are provided.
Open access article. Creative Commons Attribution 4.0 International LIcense (CC BY 4.0) applies
Play fighting in rats , Pinning , Pin configuration , Defensive action , Playful attack
Himmler, S. M., Himmler, B. T., Stryjek, R., Modlinska, K., Pisula, W., & Pellis, S. M. (2016). Pinning in the play fighting of rats: A comparative perspective with methodological recommendations. International Journal of Comparative Psychology, 29.