Different kinds of ‘skill transfer’

When I was a PhD student, I learned that there are 3 main topics of investigation in skill learning research: skill acquisition, skill retention, and skill transfer. The goal of researchers interested in skill ought to be to understand the processes by which these things happen, and to develop ways to enhance them.

The first two are fairly easy to define. Skill acquisition is the improvement of performance at a previously unlearned task, usually through repetition and training. Researchers might ask how to accelerate this process, or how to ensure that training/practice conditions ensure the most adaptive and long-lasting learning. Skill retention is the ability to perform well at the now-learned task after extended time periods, or following interference of another task/skill. ‘You never forget how to ride a bike’ = skill retention. In the research literature, retention is generally used as a metre stick to evaluate how successful the acquisition phase has been. Both acquisition and retention are (reasonably) well-defined and have been extensively researched.

Skill transfer is far less easy to define than acquisition or retention, and, while the most elusive, it is perhaps the most desirable phenomenon. It is something like the ability to perform an unrehearsed skill as the result of having previously acquired and retained a different-but-related skill. This definition has many problems and does not capture the idea of transfer fully. Examples might be better. Imagine a proficient Gaelic football player switching to Rugby – we might expect that many of the sub-skills required to do well in Gaelic would transfer to rugby, even if not all. Or a cello player taking up the viola. While the new instrument is a fraction of the size of the former, and played in a completely different posture, we might expect some of the learned skill to carry over. Of more general relevance, how can practice of one thing transfer to unpracticed situations? How can set-piece drills transfer to a real match against another team? How can rehearsing jazz scales transfer to a live improvisation during a gig? These are the kinds of phenomena and questions that skill transfer as a concept is supposed to capture.

An idea that I have been wondering about recently (and haven’t yet had the time to fully research) is about the different ways we could conceptualise skill transfer. Typically, the idea is that ‘acquisition of the skill to perform Task A will reliably result in better performance in Task B’ (assuming that Task A and B are similar enough in the relevant ways¹). However, I think there is another way of thinking about transfer. This is that ‘acquisition of the skill to perform Task A will reliably result in faster/better acquisition of the skill to perform Task B’. This may reveal itself independently of initial performance at Task B. Rather, by having tuned into the information that allowed Task A to be learned, and assuming that such information is meaningfully present in Task B, the learner will more readily be able to attune their attention to this in learning Task B and show accelerated acquisition. I am inspired here by the common anecdote² that having learned one instrument to a proficient level, it is easier to learn a second, and then easier still to learn a third, and so on. Thus, one view of transfer is improved performance of the unpractised task, while another would be improved learning of the unpractised task. The distinction may relate in part to a contrast between between ‘pick-up of information for action’ and ‘pick-up of information for learning’, but I am not yet in a position to formulate this idea fully yet.

I am sure that there is research relevant to this question out there. However, I have certainly not come across an explicit distinction between these two possible (and not mutually exclusive) ways that learning one skill could benefit another skill. I hope to look into this question further soon and report back with what I find.


  1. What counts as ‘the relevant ways’ is hugely important, and probably at the heart of the question of skill transfer, but something I will leave alone for now.
  2. I will look for proper evidence of this idea.

Our senses limit our actions, and this is a good thing

It can be so helpful sometimes to revisit older texts that were part of your intellectual trail, but which haven’t been retread for a while. Today, I met with my PhD student Alannah to discuss a book chapter by Karl Newell, ‘Constraints on the Development of Coordination‘. The last time I thought about this paper properly was when Johann Issartel and I set out to write a critique of it 10 years ago (this has yet to materialise, but may happen yet), and I haven’t looked at it since then. Alannah’s project is about motor development in children with visual-impairment, and so it seemed like a relevant source of theoretical ideas for her thesis, and something that would be worth discussing. I’m very glad we did.

The paper sets out a theory of the development of coordination, essentially the principles by which children come to acquire skilful control of their movements. A central idea is as follows. There are too many ways to move. All the possible ways of rotating joints, contracting or relaxing muscles, and shifting limb parts through space, means that there is a huge mathematical problem for the developing brain to solve: how to reduce these possibilities from an infinite set to a workable set for controlling intentional behaviour (this is a crude summary of Bernstein’s Degrees of Freedom problem).

Part of the answer to this problem lies in the concept of ‘constraints‘. Constraints are limits on how physical things can move. Gravity. Limb mass. The material springiness of connections between muscles, ligaments, tendons, and bones. Boundaries of frequencies of signals to and from the central nervous system. The properties of structures, objects and events in the immediate environment. All these things reduce the degrees of freedom available. Thus, coordinated behaviour emerges from how different constraints force organisation of the component parts involved. As a somewhat removed illustration, a murmuration of starlings emerges from the combined constraints of gravity, air-flow, wing shape, and a few simple (though yet undiscovered) rules governing how each bird responds to motions of other birds in their visual field. Rather than thousands of birds all flying around at random, these constraints limit their possible paths of motion to a smaller subset of codependent trajectories. The results is a beautiful, coordinated complex system (see video below). The idea is that human (and other animal) movement obeys similar natural laws, whatever they may turn out to be. Thus, the concept of constraints on coordination provides a starting point to a solution to the Degrees of Freedom problem. This idea is summarised nicely in a line quoted from another paper by Kugler, Kelso and Turvey: “it is not that actions are caused by constraints, it is rather that some actions are excluded by them”.

Importantly, information picked up through our senses can also constrain movement. That is, when functioning to guide action, vision/audition/proprioception/etc., all limit the range movements that can/should be made. We tested (informally) this idea today, by having me close my eyes and draw a figure-of-eight in the air. When I made the same movements with eyes open, the pattern was more accurate, and consistent. The set of finger movement possibilities was reduced by the visual constraint of how my limb moved in relation to the intended pattern. Perception limits action. This brings me to a ‘Eureka’ moment I had when re-reading the paper, and which Alannah and I discussed in earnest today.

Visual-impairment is not a constraint on coordination, but rather a reduction in constraints. Having limited or no visual access to one’s own limbs, or objects/structures/events in the environment, does not limit movement but rather removes a limit on movement. Thus, movement development is affected by having fewer informational stabilisers and contours to follow.  Of course, other modalities (audition, proprioception, etc.) can and do impose constraints on movement, and optimal patterns of coordination may be discovered by someone with visual-impairment through these limiters. The goal now becomes identifying the best ways to organise task and environmental constraints to help the children uncover these solutions, rather than trying to replace visual ‘input’ through other channels. As a result, thinking about vision and other senses as limitations on movement will really shift the way Alannah and I have been viewing perceptual motor development in children with visual-impairment.

(Re-)reading older papers is a good idea!

Musicians keeping together in time

I gave a guest lecture yesterday on the topic of ‘Action’ in Music Psychology. This was for a colleague/friend, Trevor Agus, who runs a course called Music Psychology for students enrolled on Music programmes in the School of Arts, English and Languages. We amuse ourselves that he teaches Music Psychology to music students, while I teach Psychology of Music to psychology students. This was the second time I have given this class.

It is an odd thing for me to teach a class on Psychology of Action to music students, not least because I almost could have become a music student myself at one point in my life. Instead, I became a student of philosophy and psychology, and then movement, and then movement in music, etc. Ah, well. It feels very different trying to impart a message about motor coordination and skill acquisition to musicians than to impart the same message to psychologists. The things that feel the need for emphasis differ, and the ideas that capture the room differ too.

One idea from the class that I was happily reminded of in preparing for it is the complex challenge of musicians coordinating with each other in ensemble performance. It is a miraculous thing enough that one nervous-muscular-skeletal system can coordinate its own behaviour to give rise to musical performance, but it is even more miraculous that many of these systems can not only coordinate their own sounding actions, but also coordinate with each others’ actions. Much of the research into this phenomenon is focussed on either measuring timing between musicians (e.g. the correlations of note interval variations between musicians), or on identifying the perceptual signals that might support musicians in the task of interpersonal musical coordination. In the latter case, the visual cues from body movements and gestures (both intentional and unintentional) seem to play a pretty big part in helping musicians to stay coordinated with each other while enacting a performance.

An example of this that I used in the class is from a concert by the Penguin Cafe Orchestra filmed for the BBC in the mid-80s. In the performance of Air á Danser, a section of the piece involves the group slowing down together a couple of times, then speeding back up to resume the flow of the music. Simon Jeffes, the leader of the group, conducts this process through a combination of head movements, eye contact and body gestures, with the result that around a dozen separate musicians are able to control the timing of their actions as a single unified system. The video clip of the whole track is embedded below, and the section in particular begins at around 1:05. It’s a lovely example of multisensory interpersonal coordination in musical performance, as well as being a very charming piece of music (in my opinion, at least).



This is the first post on Coordinating with Sound.

I want to explain the grey waveform image that forms the header to this site. The image is of the transition between an audio signal (a short snippet of Fela Kuti’s Open and Close) and a motion capture signal (taken from an experiment I ran with Mihalis Doumas in which participants had to move their finger side-to-side between two targets in time with different rhythmic sounds). I created the image in Matlab by normalising the two signals (audio and mocap) and phasing from one to the other. The bottom signal is just the reverse of the top.

The reason I mention this is that I sometimes found it useful to think of motion and sound as signals, that is, quantifiable patterns of fluctuation over time. Of course, there are many different ways that both sound and movement can be represented as signals, and lots of theoretical issues in the choices that go into these representations (topics for future discussions no doubt). Nevertheless, by thinking of sound and movement as signals, we can analyse similarities and differences in their forms, and look for connections between these. Hence this image as the header for the site.