The competitive reaction time task: The development and scientific utility of a flexible laboratory aggression paradigm

Laboratory measures play an important role in the study of aggression because they allow researchers to make causal inferences. However, these measures have also been criticized. In particular, the competitive reaction time task (CRTT) has been criticized for allowing aggression to be operationalized in multiple ways, leaving it susceptible to “p-hacking.” This article describes the development of the CRTT and the ways in which its paradigm flexibility and analytic flexibility allows it to test a wide range of hypotheses and research questions. This flexibility gives the CRTT significant scientific utility, but as with any research paradigm, comes with the obligation that it has to be used with integrity. Although safeguards exist and there is little evidence of misuse, study preregistration can increase confidence in CRTT findings. The importance of findings such as those of Hyatt et al. (in press), which provide further evidence for the validity of the CRTT, are also noted.     

Social group norms,school norms,and children's aggressive intentions

This study examined whether the effect of social group norms on 7‐ and 10‐year‐old children's aggression can be moderated or extinguished by contrary school norms. Children (n=384) participated in a simulation in which they were assigned membership in a social group for a drawing competition against an outgroup. Participants learnt that their group had a norm of inclusion, exclusion, or exclusion‐plus‐relational aggression, toward non‐group members, and that the school either had a norm of inclusion, or no such norm. Findings indicated that group norms influenced the participants' direct and indirect aggressive intentions, but that the school norm moderated the group norm effect, with the school's norm effect tending to be greater for indirect vs. direct aggression, males vs. females, and younger vs. older participants. Discussion focused on how school norms can be developed, endorsed, and presented so that they have their most lasting effect on children. Aggr. Behav. 36:195–204, 2010. © 2010 Wiley‐Liss, Inc.     

High maternal aggression in dwarf hamsters (Phodopus campbelli and P. sungorus)

The defense of offspring, termed maternal aggression, is a highly conserved behavior in mammals, including rodents. This study examined relative levels of maternal aggression in two closely related dwarf hamster species, Phodopus campbelli and P. sungorus, that normally inhabit high latitude, boreal environments. When tested with first litters and with the breeder male remaining with the female (for P. campbelli the male is necessary for successful rearing of offspring), both species exhibited high levels of maternal aggression with average duration of aggressive behavior>80 sec for a 10 min test. For P. sungorus, males are not required to rear offspring. P. sungorus females with either one or multiple litters (singly housed after impregnation) exhibited significantly higher levels of aggression (>300 sec) relative to females co‐housed with the sires. In terms of species differences in attack style, P. campbelli exhibited a boxing or clawing strategy for ～50% of total attack time, but for P. sungorus, this form of attack occurred<5% of the time. For P. sungorus, attacks to the vulnerable belly and flank constituted>90% of all attacks, but these regions were attacked ～50% of the time for P. campbelli. A survey of levels of maternal aggression of rodents in other genera suggests that maternal aggression in Phodopus is at the high end of the spectrum. Results of this study suggest that the presence of the breeder male may actually suppress aggression in P. sungorus. This fact, as well as its high level of aggression and its distant relationship to mice and rats, suggest P. sungorus as a possible model for future studies on the neurobiological basis of maternal aggression. The relationship between the high rates of maternal aggression and life history strategy in Phodopus is discussed. Aggr. Behav. 00:000–000, 2005. © 2005 Wiley‐Liss, Inc.