Consistency of hand preference across low‐level and high‐level tasks in Capuchin monkeys (Cebus apella)

Abstract

Numerous studies investigating behavioral lateralization in capuchins have been published. Although some research groups have reported a population-level hand preference, other researchers have argued that capuchins do not show hand preference at the population level. As task complexity influences the expression of handedness in other primate species, the purpose of this study was to collect hand preference data across a variety of high- and low-level tasks to evaluate how task complexity influences the expression of hand preference in capuchins. We tested eleven captive brown capuchin monkeys (Cebus apella) to determine if they show consistent hand preferences across multiple high- and low-level tasks. Capuchins were expected to display high intertask consistency across the high-level tasks but not the low-level tasks. Although most individuals showed significant hand preferences for each task, only two of the high-level tasks that involved similar hand motions were significantly positively correlated, indicating consistency of hand preference across these tasks only. None of the tasks elicited a group-level hand preference. High-level tasks elicited a greater strength of hand preference than did low-level tasks. No sex differences were found for the direction or strength of hand preference for any task. These results contribute to the growing database of primate laterality and provide additional evidence that capuchins do not display group-level hand preferences.

Hand Preference during Tool Use in Wild Bearded Capuchins

“…The three adult capuchins (Boludo, Adtmale and Cara-Branca) and a juvenile with the highest number of tool use bouts recorded showed consistency in hand use across different tool activities ( table 1 ). This agrees with findings by Lilak and Phillips [2007] showing that captive capuchins display consistency of hand preferences across tasks that require similar motor actions.…”

“…Combining these bouts seemed unproblematic as capuchin monkeys demonstrate consistency of hand use across different tasks [Lilak and Phillips, 2007], and more recently Hopkins [2013b] has argued in favour of characterizing hand preferences based on consistency between tasks.…”

“…The high degree of lateralization in capuchins has been highlighted in a series of studies in captive groups tested with bimanual tasks and in tool use [Westergaard and Suomi, 1996a, b;Spinozzi et al, 1998;Lilak and Phillips, 2007;Meunier and Vauclair, 2007], which could indicate asymmetries in the motor cortex [Fagot and Vauclair, 1991;Phillips and Thompson, 2013]. Tool use, particularly nut cracking, has been associated with strong individual laterality and also population-level right-handedness in communities of wild chimpanzees [Boesch, 1991;Lonsdorf and Hopkins, 2005;Humle and Matsuzawa, 2009; but see Marchant and McGrew, 2013] and in captive groups of capuchin monkeys the use of tools to pound/crack is right-handed [Westergaard and Suomi, 1996b].…”

Precise digit use increases the expression of handedness in Colombian spider monkeys (Ateles fusciceps rufiventris)

“…We hypothesized that task complexity, defined here by the motor constraints placed on hand and digit use, is related to the expression of handedness [e.g., Fagot & Vauclair, 1991;Lilak & Phillips, 2008]. We predicted that role-differentiated action coupled with precise digit use would increase hand preference strength, but would not impact hand preference direction.…”

Laterality of Grooming and Tool Use in a Group of Captive Bonobos (Pan paniscus)

“…Our cumulative knowledge is largely drawn from chimpanzees (e.g., Corp and Byrne [2004], Hopkins et al [2007], McGrew and Marchant [2001]) although the number of studies focusing on bonobos (e.g., Bardo et al [2015], Chapelain et al [2011], Harrison and Nystrom [2008], Hopkins et al [2011Hopkins et al [ , 2015, Neufuss et al [2017], Shafer [1997) and other taxa (e.g., capuchins [Lilak and Phillips, 2008], snub-nosed monkeys [Zhao et al, 2010]) are increasing. The present study confirms our prediction that a complex task (termite fishing) would elicit hand preference among captive bonobos whereas a simpler task (grooming) would not.…”