Personality method validation in common marmosets (Callithrix jacchus): Getting the best of both worlds.

Abstract

Animal personality, consistent interindividual differences in behavior through time, has been intensively studied across animal taxa and particularly in nonhuman primates. Two different methods have been used to study personality: questionnaires filled out by trusted raters, following the research tradition in human personality psychology, and behavioral observations or testing, based on the behavioral ecology research tradition. Systematic research of cross-method validity has, however, brought equivocal results. Here we report a systematic method comparison with strict validation criteria in common marmosets (Callithrix jacchus). We compared questionnaire data, observational behavioral data, and experimentally assessed behavioral data independently collected in two different research laboratories and across two years. Notably, we constructed a priori predictions on the degree and direction of correlations between the questionnaire-derived constructs and behaviorally derived constructs/variables. Convergent validity of the constructs/variables was present but was not found in both laboratories for any of the constructs. Discriminant validity was found to some degree for all constructs in both laboratories, with important exceptions. It seems that marmoset personality structure obtained with descriptor ratings does not consistently capture the predicted behavioral variables. Our finding that these two methods do not quite reach common ground thus urges caution in the choice of the suitable methods to study personality in nonhuman primates. We discuss the directions to which animal personality research should go so that it can get the “best of both worlds.”

Temporal consistency and ecological validity of personality structure in common marmosets (Callithrix jacchus): A unifying field and laboratory approach

“…Common marmosets ( Callithrix jacchus ) are highly social cooperatively breeding New World primates that live in cohesive family groups in a variety of different habitats, from the Atlantic rain forest to the semiarid area of shrub forests (Garber et al, 2019) and have been studied in a variety of socio‐cognitive questions (Schiel & Souto, 2017). In recent years, these monkeys have become the focus of personality studies under lab conditions: they display consistent interindividual differences when assessed in a battery of experiments (Díaz et al, 2020; Koski & Burkart, 2015; Šlipogor et al, 2016; Tomassetti et al, 2019), observations (Martin et al, 2019; Masilkova et al, 2020; Šlipogor et al, 2020), questionnaires (Inoue‐Murayama et al, 2018; Koski et al, 2017; Weiss et al, 2020), and by using a combination of several different personality assessment methods (Iwanicki & Lehmann, 2015; Šlipogor et al, 2020). However, little is known about long‐term consistency of their personality structure, and no study to this date assessed the personality of wild common marmoset populations.…”

“…Nonhuman primate personality has usually been studied in captivity (e.g., Capitanio 1999, 2004; Koski, 2011; Masilkova et al, 2018; Šlipogor et al, 2016, 2020; Stevenson‐Hinde & Zunz, 1978; Stevenson‐Hinde et al, 1980a, 1980b; Uher & Visalberghi, 2016; Uher et al, 2008; Uher et al, 2013; Wilson et al, 2018), and, to a somewhat lesser extent, also in the wild (e.g., Fernández‐Bolaños et al, 2020; Carter et al, 2014b; Dammhahn & Almeling, 2012; Ebenau et al, 2020; Eckardt et al, 2015; Garai et al, 2016; Konečná et al, 2008; Manson & Perry, 2013). Personality trait correlations are likely maintained by mechanisms that may either constrain behavioral changes (i.e., “constraint hypothesis”; Bell, 2005; Lande, 1979) or particular traits may be selected for in some distinct environments (i.e., “adaptive hypothesis”; Bell, 2005; Lande & Arnold, 1983).…”

Measuring personality traits in Eurasian red squirrels: A critical comparison of different methods

“…Animal personality is defined as consistent among‐individual differences in behaviour which persist through time and in different contexts (Carter et al., 2013; Koski, 2014; Réale et al., 2007) and is commonly described by several underlying personality traits, each of which reflects a particular aspect of an individual's behavioural repertoire (Carter et al., 2013; Réale et al., 2007). Personality has been documented across taxa in several recent studies (insects: Crall et al., 2018; fish: Barber et al., 2017; Jolles et al., 2019; reptiles: Horváth et al., 2019; Michelangeli et al., 2019; birds: Morinay et al., 2019; Richardson et al., 2019; mammals: Brehm et al., 2019; DeRango et al., 2019; Petelle et al., 2019), and personality traits such as activity (Michelangeli et al., 2019), exploration (Arvidsson et al., 2017) and boldness–shyness (Jolly et al., 2019; Perals et al., 2017) have been quantified using different methods under laboratory conditions and in free‐living populations in the wild (Krebs et al., 2019; Réale et al., 2007; Šlipogor et al., 2020; Tkaczynski et al., 2019).…”

Personality, Subjective Well-Being, and the Serotonin 1a Receptor Gene in Common Marmosets (Callithrix jacchus)

“…However, there is also evidence, at least for personality traits in this species, for plasticity, either via social facilitation or via social group effects (12). There also appears to be mixed evidence for the construct validity of common marmoset personality traits, that is, for convergent and discriminant validity between personality ratings, behavioral observations, and responses to behavioral tests (13). Finally, studies of common marmoset personality that relied on behavioral measures have revealed an association between a factor labeled "Inquisitiveness" and the strength of laterality (14), and various associations between factors labeled "Sociability", "Aggressiveness", and "Social Anxiety" and the binding potential of serotonin transporters in the brain (15).…”