On the Difference Between Dexterity and Coordination

        I love watching talent shows. Beyond their entertainment value, they often remind me of the incredible feats and skills humans can accomplish, an admittedly ironic statement given the auditionees who inspired this blog entry. I was recently sent a clip from America's Got Talent showcasing a human dancer performing alongside a group of humanoid robots. Astonishingly, not only were these robots executing dance moves and performing front flips (what??), but they were also performing in synchrony, creating mesmerising patterns that would impress even the most stoic audience member. Anyone would call these robots coordinated, and why not? They each demonstrate internal coordination, controlling the many joints and degrees of freedom present in their metallic frames to produce eye-catching movements that solve various motor problems (e.g., maintaining balance after the front flip). Additionally, they collectively demonstrate external coordination by maintaining spatial equidistance and temporal synchronisation despite the innumerable ways in which these orders might be disrupted. According to Bernstein's definition of coordination (see here), it seems that both within- and between-robot coordination are on display.

        Yet, Bernstein's end goal was never coordination. A quick look at the titles of his book (On Dexterity and its Development), first essay (What is Dexterity?), and last essay (Dexterity and its Features) suggests that an account of dexterity was what he was after. So, do the humanoid robots demonstrate dexterity? What is dexterity anyway? And more importantly, what are the differences between dexterity and coordination? In this blog, I aim to provide a systematic approach to answering these questions, covering perspectives from the layman, Bernstein, and also some additional input from my end. Although our everyday definitions suggest that dexterity represents a subset of coordination, Bernstein regarded the two as distinct concepts. Coordination concerns the internal relations within a movement system; dexterity, by contrast, encompasses both these relations and the external motor problem the system seeks to solve. Unfortunately,  I believe Bernstein's treatment of coordination is slightly simplistic. By building on his developed view on the two motor terms, I argue that coordination actually represents a subset of dexterity (which, given how we started, is somewhat of an unexpected reversal). For transparency, the reader should be informed that at the time of writing, I have read only five of Bernstein's seven essays. It is entirely possible that I have misrepresented Bernstein's views. Comments and discussion are always welcome!

Problems of Motor Coordination and their Evolutionary Origins

        Animals are constantly moving. Insects crawl, fish swim, frogs hop, penguins waddle, horses trot and gallop, while humans walk, reach, grasp, jump and much, much more. Clearly, there are many ways to coordinate the muscles, joints, ligaments, tendons, and bones that make up the skeletal-articular-muscular movement apparatus (i.e., our bodies). While the question of how we coordinate movement may seem like an intuitive and trivial problem to solve, the scientist faces many challenges in finding a satisfactory answer. This begs the question: what makes motor coordination so challenging? At the same time, we can see clear differences in the demands placed on coordination by different animals, not least because of their different bodily structures. No doubt coordinating movement has become much harder since the beginning of life. For example, single-celled organisms definitely do not face the same level of difficulty coordinating movement as humans or dogs do. In this blog, I draw heavily on Essays 2 and 3 of Nikolai Bernstein's On Dexterity and Its Development (Bernstein, 1996) to outline the challenges of motor coordination and to identify their evolutionary origins. While the essays tackle these issues separately, I aim to provide a coherent synthesis of Bernstein's insights by drawing direct links between each coordination challenge and a specific evolutionary event. Of course, this is not to say that the problems of coordination are caused by single evolutionary events. Rather, they are highlighted merely as notable events among the many which have led to such difficulties in controlling movement.