Aggressiveness as a latent personality trait of domestic dogs: testing local independence and measurement invariance

Abstract

8Studies of animal personality attempt to uncover underlying or 'latent' personality traits 9 that explain broad patterns of behaviour, often by applying latent variable statistical 10 models (e.g. factor analysis) to multivariate data sets. Two integral, but infrequently 11 confirmed, assumptions of latent variable models in animal personality are: i) behavioural 12 variables are independent (i.e. uncorrelated) conditional on the latent personality traits 13 they reflect (local independence), and ii) personality traits are associated with 14 behavioural variables in the same way across individuals or groups of individuals 15 (measurement invariance). We tested these assumptions using observations of aggression 16 in four age classes (4 -10 months, 10 months -3 years, 3 -6 years, over 6 years) of male 17 However, certain contexts related to aggressiveness towards people (but not dogs) shared 24 significant residual relationships unaccounted for by latent levels of aggressiveness. 25Furthermore, aggressiveness towards people and dogs in different contexts interacted 26 with sex and age. Thus, sex and age differences in displays of aggression were not simple 27 functions of underlying aggressiveness. Our results illustrate that the robustness of traits 28 in latent variable models must be critically assessed before making conclusions about the 29 effects of, or factors influencing, animal personality. Our findings are of concern because 30

Modelling personality, plasticity and predictability in shelter dogs

“…Inter-rater reliability and the validity of the assessment methodology were evaluated using 167 data from a larger research project at the shelter. Videos depicting different behaviours 168 in different contexts were filmed by canine behaviourists working at the shelter, who subse-169 quently organised video coding sessions with 93 staff members (each session with about 5 -10 170 participants) across rehoming centres [35]. The authors were blind to the videos and admin- distribution, φ, with mean, µ, SD σ and thresholds θ c : To model inter-and intra-individual variation, a hierarchical structure for both the mean 227 and SD was specified.…”

“…114 We did not include breed characterisation due to the unreliability of using appearance to 115 attribute breed type to shelter dogs of uncertain heritage [34]. 116 2.2 Shelter environment 117Details of the shelter environment have previously been presented in [35]. Briefly, the shelter 118 was composed of three different rehoming centres (Table 1): one large inner-city centre based 119 in London (approximate capacity: 150-200 dogs), a medium-sized suburban/rural centre 120 based in Old Windsor (approximate capacity: 100-150 dogs), and a smaller rural centre in 121Brands Hatch (approximate capacity: 50 dogs).…”

“…Details of the shelter environment have previously been presented in [35]. Briefly, the shelter 118 was composed of three different rehoming centres (Table 1): one large inner-city centre based 119 in London (approximate capacity: 150-200 dogs), a medium-sized suburban/rural centre 120 based in Old Windsor (approximate capacity: 100-150 dogs), and a smaller rural centre in 121…”

“…Personality 30frequently describes less than 50% of behavioural variation in animal personality studies [1, 31 2], leading to the combined analysis of personality with plasticity, individual differences in 32 behavioural change [3], and predictability, individual differences in residual intra-individual 33 variability [4][5][6][7][8]. Understanding these different sources of behavioural variation simultane-34 ously can be achieved using the general framework of behavioural reaction norms [3, 5], 35 which provides insight into how animals react to fluctuating environments through time and 36 across contexts. More generally, these developments reflect increasing interest across biology 37 in expanding the 'trait space' of phenotypic evolution [9] beyond mean trait differences and 38 systematic plasticity across environmental gradients to include residual trait variation (e.g.…”