The Development of Motor Self-Regulation in Ravens

Abstract

Inhibitory control refers to the ability to stop impulses in favor of more appropriate behavior, and it constitutes one of the underlying cognitive functions associated with cognitive flexibility. Much attention has been given to cross-species comparisons of inhibitory control; however, less is known about how and when these abilities develop. Mapping the ontogeny of inhibitory control in different species may therefore reveal foundational elements behind cognitive processes and their evolution. In this study, we tested the development of motor self-regulation in raven chicks (Corvus corax), using two detour tasks that required inhibition of motor impulses to directly reach for a visible reward behind a barrier. One task included a mesh barrier, which partly occluded the reward, and the other task used a completely transparent barrier, the cylinder task. The results suggest that the more visible a reward is, the more difficult it is to inhibit motor impulses toward it, and further, that this inhibitory challenge gradually decreases during development. The mesh barrier is reliably detoured before the animals pass the task with the wholly transparent cylinder. As the majority of the birds begun testing as nestlings, and as we provided them with experiences they normally would not receive in a nest, it is likely that they showed the earliest possible onset of these skills. A control subject, tested at a later age, showed that the mesh detours required no particular training, but that tasks including complete transparency likely require more specific experiences. Adult ravens without explicit training are highly proficient in inhibitory detour tasks, and, together with chimpanzees, they are the best performers of all tested species in the cylinder task. Our results suggest that their skills develop early in life, around their third month. Their developmental pattern of inhibitory skills for detours resembles that of children and rhesus macaques, albeit the pace of development is markedly faster in ravens. Investigating the development of cognition is crucial to understanding its foundations within and across species.

The detour paradigm in animal cognition

“…For example, they can reveal if different species attain similar cognitive skills using similar or different building blocks (Osvath et al 2014 ). Despite this potential importance, there are few comparative developmental studies, with rhesus monkeys and ravens representing the only non-human species tested longitudinally through development (Diamond 1990 ; Kabadayi et al 2017b ).…”

“…Raven chicks have similar difficulties during development in inhibiting a direct reach for a reward behind a transparent barrier, but they overcome this difficulty and succeed in the cylinder task when they are around 10 weeks old (Kabadayi et al 2017b ). Before the 10th week, and after they attain object permanence, they perform better on opaque barriers than transparent ones.…”

“…Developmental studies can also demarcate the relative contributions of motor experience and cognitive maturation in solving detour problems. For example, Diamond ( 1988 ) found human infants tested longitudinally (tested every second week) succeeded on the detour reaching task around 2–4 weeks earlier than infants in the cross-sectional group [for a similar finding in ravens see Kabadayi et al ( 2017b )]. This suggests repeated motor experience with the task helps infants solve the task earlier, and the successful detours develop not solely from a task-independent inhibitory maturation, but also from an interaction of various processes such as sensorimotor experience with the barrier as well as motor coordination (Williams et al 2015 ).…”

Are lizards capable of inhibitory control? Performance on a semi-transparent version of the cylinder task in five species of Australian skinks

“…One commonly used detour task is the "cylinder task" (MacLean et al 2014), a two-stage response inhibition task, in which animals are first trained to make a detour to the side openings of an opaque cylinder containing a reward which is invisible prior to approach. Thereafter, the opaque cylinder is replaced with a transparent cylinder to test motor response inhibition by quantifying successful detours when a reward is visible (e.g., Boogert et al 2011;Bray et al 2014;MacLean et al 2014;Anderson et al 2016;Kabadayi et al 2016Kabadayi et al , 2017bVernouillet et al 2016Vernouillet et al , 2018Lucon-Xiccato et al 2017;Bobrowicz and Osvath 2018;Isaksson et al 2018;Szabo et al 2019b).…”

“…The proficiency with which inhibitory control is executed also differs among species (e.g., MacLean et al 2014;Kabadayi et al 2016Kabadayi et al , 2017bRudolph and Fichtel 2017;Brucks et al 2018). In the case of cylinder tasks, the best scores were achieved by great apes (MacLean et al 2014), corvids (Kabadayi et al 2016), and carnivores such as dingos, dogs, and cats (MacLean et al 2014;Bobrowicz and Osvath 2018).…”