Postural effect on manual laterality in different tasks in captive grey-cheeked mangabey (Lophocebus albigena)

The authors examined the effects of task complexity and posture on laterality and compared lateralization during different tasks in 9 captive grey-cheeked mangabeys (Lophocebus albigena) during spontaneous food processing and 3 experimental tasks. Comparisons with data of red-capped mangabeys (Cercocebus torquatus torquatus; semiterrestrial species) were used. Less than half the monkeys were lateralized for simple […]

Self-control and tool use in tufted capuchin monkeys (Cebus apella)

Self-control is defined as forgoing immediate gratification to obtain a greater reward. Tool use may relate to self-control because both behaviors may require foresight and deliberate control over one’s actions. The authors assessed 20 capuchin monkeys ( Cebus apella) for the ability to delay gratification in a tool task. Subjects were given rod-shaped food items […]

Gorillas (Gorilla gorilla) and Orangutans (Pongo pygmaeus) Encode Relevant Problem Features in a Tool-Using Task

Two important elements in problem solving are the abilities to encode relevant task features and to combine multiple actions to achieve the goal. The authors investigated these 2 elements in a task in which gorillas (Gorilla gorilla) and orangutans (Pongo pygmaeus) had to use a tool to retrieve an out-of-reach reward. Subjects were able to […]

Observing Conspecifics Scratching Induces a Contagion of Scratching in Japanese Monkeys (Macaca fuscata)

Although a large number of studies have examined self-directed behaviors (SDBs) such as scratching and self-grooming as nonverbal leakage of negative emotional arousal in humans, few studies have investigated the informative function of SDBs in nonhuman primates. The present study investigated whether viewing another monkey scratching itself elicited negative arousal from conspecific observers in Japanese […]