Personality differences in House mice
This article is a translation into English of the internal discussion paper in Dutch "Uitspraken over muizen; Een differentieel-ethologische analyse van het sociale gedrag met bijzondere aandacht voor agressie" by Popko P. van der Molen. That paper has been registered in July 1977 as HB-77-308-IN, (Heymans Bulletin Psychologische Instituten R.U. Groningen).
This paper reports ethological research on 36 male house mice (Mus musculus), living in social groups of 4 brothers and 2 sisters in large observation cages with plenty nesting boxes, food, water, climbing objects and hiding places.
Alpha, Bèta and Omega social roles of male mice were studied and experiments were conducted with 31 of such populations or groups in order to determine the factors that determine which male will adopt which social role in a certain, specific situation.
Next, a factor-analysis (Q-technique) was conducted on the ethological protocol-data of 36 males in order to chart differences in the behaviour between the individuals. Reversability of social roles was demonstrated as well as the dependence of the different reaction patterns on the territorial location.
Different types of aggressive behaviour were analysed and their different functions in social interactions.
Internal and external reasons for aggressive behaviour were investigated and on the basis of the results a different approach was suggested for the concept of "aggressive" behaviour, based on a dynamic model of personality differences between male mice.