Manual lateralization in wild redfronted lemurs (Eulemur rufifrons) during spontaneous actions and in an experimental task

Abstract

The dominant use of one hand is a striking feature of humans, but manual lateralization can be found in a variety of other species as well. In primates, the lateralization in hand use varies among species and several theories such as the "postural origin," "task complexity," or "development theory" have been suggested to explain this variation. In order to contribute comparative data on this phenomenon from a basal primate, we studied manual lateralization in wild redfronted lemurs (Eulemur rufifrons). Data were collected on four groups at Kirindy Forest, western Madagascar, during spontaneous actions and by confronting them with artificial feeding boxes. The lemurs did not exhibit manual lateralization on a group level in either condition. More individuals showed a hand preference in the experimental task, and the preferences were stronger compared to spontaneous actions. The direction of individual hand preferences was not consistent across the two conditions. The results of this study show that measuring manual laterality in different contexts can yield different results. Manual lateralization in wild redfronted lemurs therefore seems to be flexible and situation dependent and probably not ecologically relevant in their natural habitat.

Hand preferences and differences in extractive foraging in seven capuchin monkey species

“…In the case of methodological issues, the objection seems to boil down to the type of tasks used for measuring hand preference. In general, tasks that do not require cognitive and motor demanding actions, such as the commonly‐used manual reaching for food, hardly evoke hand preference in non‐human primates (Fagot & Vauclair, ; Papademetriou et al, ; Schnoell, Huebner, Kappeler, & Fitchel, ). According to the task complexity hypothesis, proposed by Fagot & Vauclair (), high‐level tasks, that is, those needing cognitively demanding requirements, tend to elicit stronger hand preference in non‐human primates, although this hypothesis does not make predictions about direction of hand preference.…”

Hand preference on unimanual and bimanual tasks in strepsirrhines: The case of the ring‐tailed lemur (Lemur catta)

“…According to previous literature on lemur manual lateralization, the finding of a group‐level hand preference is quite unusual. Indeed, prior studies on this topic usually failed to reveal a significant bias in hand use for simple reaching and other unimanual actions [Leliveld et al, ; Lhota et al, ; Rigamonti et al, ; Schnoell et al, ], although it has been reported a tendency toward a left‐handedness in strepsirrhines [for review, see: Ward et al, ], including a sample of ring‐tailed lemurs [Milliken et al, ; Shaw et al, ]. However, as mentioned above, most studies on strepsirrhine hand preference have relied on the measurement of simple and spontaneous actions.…”

“…In both the unimanual and bimanual task, bouts of hand preference were considered, meaning that only the hand starting an action subset was recorded, to guarantee independence of data points [McGrew & Marchant, ; Schnoell et al, ]. To avoid a learning effect on lemur hand preference, each session was limited to a maximum of five trials; a new trial was considered only after the lemur finished interacting with the apparatus, changed its posture or was in a symmetrical position (in front of the apparatus).…”

“…To avoid a learning effect on lemur hand preference, each session was limited to a maximum of five trials; a new trial was considered only after the lemur finished interacting with the apparatus, changed its posture or was in a symmetrical position (in front of the apparatus). In both tasks, a number of sessions were conducted in order to collect 50 bouts [Palmer, ; Schnoell et al, ] per behavioral category per subject.…”

“…[for review, see Ward et al, ] and Senegal bushbabies ( Galago senegalensis ) [Larson et al, ; Sanford et al, ]. More recently, it has been reported a lack of group‐level hand preference in Malagasy strepsirrhines for foraging and other spontaneous natural activities in species such as indri ( Indri indri ) [Rigamonti et al, ], M. murinus and M. lehilahytsara [Leliveld et al, ], aye‐ayes ( Daubentonia madagascariensis ) [Lhota et al, ], and red‐fronted lemurs ( Eulemur rufifrons ) [Schnoell et al, ].…”