What can we do with sounds? (Part 1)

A few months ago, Andrew Wilson tweeted a hypothesis:

He had previously suggested something similar to me at EWEP15, although not in as strong a form. In this form, the hypothesis is plainly false, given the ambiguity around the word ‘specialise’ and the fact that many animals – including humans – perceive events and properties of the environment through sound, and not always through echolocation (even among bats, not all species use echolocation, or use it as the sole means to localise targets and navigate their environments). However, after replying to say as much, Andrew refined the hypothesis to something that I think is more conceptually interesting and challenging to those of us interested in auditory perception for action:

This question has been rattling around my head since the summer, and I have been meaning to write up my thoughts on here for a while. However, I’ve since realised that the question itself raises a number of different issues and ideas about auditory perception, its functions, and its comparability to other senses. These are relevant to the development of Sensory-Substitution Devices (SSDs), but I think reach into more general questions about auditory perception for action. As such, I’m going to try and tackle this over a number of posts (at some point over the coming year, I promise).

What can we do with sounds and what can’t we do?

To begin with, I thought it might be useful to group some activities, abilities and skills into those that humans specialise using sound to achieve, those that are typically guided by vision but which may be guided/influenced by sound, and those for which sound is pretty much useless compared with vision.

Things that humans do well (specialise) with sound over vision

  • Perceive and control speech (however: McGurk effect)
  • Perceive and make music (however: vision can influence perception of musical performances: 1, 2, 3)
  • Localise events and objects outside visual field, albeit less precisely than through vision

Things that humans do well (specialise) with vision, though may be able to do to a lesser ability using (naturally occurring/non-artificial) sounds

Things that humans do well (specialise) with vision, that are impossible using (naturally occurring/non-artificial) sounds

  • Read text
  • Perceive signs/symbols
  • Anything involving colour perception
  • Recognise faces

This catalogue is far from exhaustive (although I intend to add to it over time), but hopefully it will fuel thinking about what auditory perception may allow us to do and why. In subsequent posts, I intend to consider cases when human uses of sound may vary (as can be the case for people with visual-impairments, or in learning an auditory-based skill like a musical instrument), find out more about acoustic perception and action in non-human species, and explore theoretical ideas which may make sense of these different groupings from the perspective of an ecological approach to acoustic psychology. While I have thought about these questions of-and-on for some time now, this is very much a learning exercise and I do not yet know where my conclusions will end up. Good fun!

EWEP15: Thoughts and Reflections

Last week I attended (most of) the 15th European Workshop on Ecological Psychology (EWEP) in Mountauban, France. This was my sixth EWEP, having first attended in Madeira in 2008, and for me it is as much of a get together with friends and colleagues from around the world as it is a scholarly meeting. Still, the scientific and theoretical content of the workshop was generally of a high quality, showcasing some interesting empirical and conceptual developments in the field of ecological psychology and related domains.

Some of my highlights of the workshop:

  • As with other recent meetings, there is a strong cohort of people developing the theoretical framework(s) of ecological psychology, both in terms of tackling conceptual controversies as well as in attempting to extend the range of activities and situations that ecological psychologists might meaningfully turn their attention to. Rob Withagen presented ideas, inspired in part by the work of Tim Ingold, about how creativity emerges from doing in the context of art and architecture. Ludger van Dijk drew links between Gibson’s ideas and those of the American Pragmatists. Julian Kiverstein attempted to tackle the problem of what Clark and Toribio (1994) called ‘Representation-Hungry‘ behaviours, activities which seem to necessitate mental representations to fill-in for the absence of behaviourally-relevant environmental properties. Matthieu de Wit presented updates on his project of a ‘Gibsonian Neuroscience’, in which the concept of ‘neural re-use’ supports the re-framing of neural processes as being organised around tasks rather than anatomical regions. Finally, Ed Baggs presented recent work on the distinction between the ecological environment as a habitat for a species, and as an Umwelt for an individual agent. While there are many challenges in advancing ecological psychology along these lines, some of which I hope to discuss in the blog soon, it is great to see people continue to enthusiastically engage with core concepts in these ways and I look forward to tracking their developments.
  • Another pattern I noticed was that a number of presentations featured data on how different individuals performed in different tasks, either as individual cases or in figures which showed the full range of performance/perception of an experimental cohort. Information about individual differences is key to better understanding issues in development, skill acquisition, expertise, disorders, and even just for understanding skilful adaptability in simple perceptual-motor tasks. I am encouraged to explore individual variation more in my own research, so it was inspiring to see how others engaged with the task.
  • On a related note, there were some great pieces on development (e.g. Laura Golenia‘s work on Developmental Coordination Disorder), skill learning (e.g. Daniel Leach‘s work on bimanual coordination and Agnes Henson‘s research on training new speech gestures with augmented visual feedback), and creativity (e.g. Dominic Orth‘s studies of how constraints in training may force learners to search for alternative affordances). I am delighted to see people adopting the ecological approach to engage with these psychological topics, as I think they are key to the future of the discipline.
  • An entertaining talk on the wisdom/stupidity of crowds in relation to perceived Social Identity information by Daniel Richardson, and an excellent keynote on self-organisation of collective motion in ants and humans by Vincent Fourcassié. Both of these presentations served up food for thought on how ecological psychologists might study social coordination beyond the usual dyadic interpersonal movements or sports team behaviour.
  • In general, the discussion of perception is still largely focussed on vision. However, by comparison to recent meetings, there was a greater representation of work involving auditory, haptic, and multi-sensory perception. Since I often find myself having to broaden discussions with ecological psych people away from the ‘visual fixation’ (pun-intended), this was encouraging.

Some room for change for the future:

  • The structure of the meeting was largely oral presentation-based, with these beginning at 8:30am, and finishing around or after 7pm. This was too much! Plus, with 15-minute presentations, it was a real challenge to keep up mentally with the switches between topics. The inevitable run-over of presentations meant that lunch was reduced in duration and a scheduled coffee break between sessions had to be removed. I saw hardly any of the posters due to the poster sessions coinciding with lunch, and the time for discussion with colleagues was shifted mainly to the nights. In my experience, the value of a conference is largely in the discussion, debate and planning with fellow researchers. Therefore, it was a shame that the format gobbled up a lot of the time and mental energy available to do this. This issue is not unique to EWEP, but in chatting to a number of people there emerged a feeling that perhaps there are other ways to communicate our research and make connections that are not so unidirectional and time-consuming. Given the collegiate nature of the broader EWEP community, and our aim to sustain the ecological psychology program, I think it will be important to explore different ways to facilitate discussion and collaboration in future workshops.

Learning movement sequences with music changes brain connectivity. Behavioural relevance pending…

Research Spotlight #2 Moore, E., Schaefer, R., Bastin, M., Roberts, N., & Overy, K. (2017). Diffusion tensor MRI tractography reveals increased fractional anisotropy (FA) in arcuate fasciculus following music-cued motor training. Brain and Cognition, 116, 40-46. 

A couple of weeks ago my mum emailed me a link to a BBC news article which she rightly knew would be of interest to me. It reported on a study by researchers mainly from the University of Edinburgh, and the title of the BBC article was: “Learning with music can change brain structure, says study“. This of course grabbed my attention, as I thought it could provide a neuroscientific counterpart to my PhD student John Dyer’s recent work, which had found that triggering a melody with one’s movements helped in learning and recalling a complex bimanual coordination task (tracing a diamond with one hand and a triangle with the other to create a 4:3 rhythm). The study by Moore et al. on which the BBC article was based is indeed interesting, but probably creates more questions than it answers. It also ties in neatly with an ongoing issue in neuroscience – trying to draw conclusions from neural measures when the behavioural framework within which they should fit is incomplete.

The study involved people learning different patterns of finger movements on their left (non-dominant hand), e.g. index-ring-middle-pinkie-ring-index-ring-middle. You can try yourself and see that it is not that easy – hence room for some learning to happen. Everyone in the study learned the task with a kind of Guitar Hero style video to show them which order the fingers had to be pressed. Importantly, one group practiced with just the video (‘control group’), while the other additionally heard musical pitches (presumably like keys on a piano) to indicate the finger order of the sequence to press. This was the key difference between the groups – one had a ‘musical’ version of the task while the other didn’t. They learned the sequences at home, and the task sped up as they got more confident at producing the sequences. They were tested at performing the rehearsed sequences as well as some sequences that they hadn’t rehearsed at three stages: before training, midway through training and after training. MRI scans of their brains were also recorded before and after training. These were used to measure changes in the organisation of fibres which connects neural cells between the auditory and motor regions of the right-hemisphere of the brain (i.e. the side of the brain which would be responsible for sending muscle signals to the left hand). The hypothesis was that learning with the musical sounds may entail greater auditory-motor linkages in the brain hemisphere involved in coordinating the task-to-be-learned.

The results of the study showed that both groups got better at the task, that is, they completed a greater number of correct sequences as a result of training. However, there were no differences in how much the music and control groups improved, that is both groups were getting pretty much the same number of correct sequences by the end of training. This is rightly taken to show that the musical tones did not influence learning (at least in terms of correct sequences). There was also evidence of a training-dependent change in the organisational structure of the axons connecting auditory and motor regions of the brain for the musical group in the right hemisphere, but not in the left hemisphere or at all in the control group. It could be noted that the changes in neural organisation were small (4% change in the main measure, all measures hovering around the 0.05 p-value), but for such a ‘light’ intervention, this may be all the more compelling – if just adding a little music to the task can change the brain, imagine what you could do if you really went to town with musical movement training!

As I said earlier, these results are certainly interesting. The lack of difference in the learning measure between the group, when one might expect the sound to be helpful, points to a need to understand better if and how sound could lead to enhanced learning of the task (e.g. through movement sonification rather than just as a guide). Also, the apparent change in neural fibres in the music group, although small, may represent a fairly surprising amount of neural plasticity in such a short space of time, more than would be expected (although I cannot comment on whether a 4% difference is that surprising or not as I am not up on what counts as small/large changes in neuroplasticity measures).

In spite of these interesting aspects, there are some limitations on what can be taken from this paper and a number of further questions raised. Firstly, it is a shame that the performance of the task was only examined using correct sequences performed. While it is always a good idea to have a primary learning measure, other measures like timing accuracy or movement kinematics may have revealed group differences which would help with understanding what the neural changes correspond to. If the neural changes are not functional for the movements involved, but rather underpin some audio-motor mapping or association which is simultaneously being acquired by the learners, then this might have been examined by looking for disruptions in performance for the music group when an incongruous finger-tone mapping is introduced following training. It is also possible that using movement sonification (fingers trigger the sounds), rather than sounds as mere cues, may have led to enhanced learning for the music group. Each of these additional measures or experimental conditions might have led to observable behavioural effects, through which the neural changes could be interpreted. As it is, however, it cannot be determined yet whether the observed changes in brain have some functional significance, or are merely an artifact, comparable to an indentation in one’s middle finger following a period of intensive handwriting.

To be fair, the authors do acknowledge that the lack of measured learning differences between the two groups limits the conclusions that can be made with regard to the neural data. Nevertheless, they do propose that the study may be valuable for clinical practice, e.g. for movement rehabilitation in Stroke survivors. The mismatch between the excitement over the seeming neural transformation (less in the paper itself but more in its media coverage) and the lack of corresponding behavioural differences between the learning conditions is telling. Recently, a group of pretty eminent neuroscientists published an excellent critique of a trend in the neurosciences to focus disproportionately on the activity and structures of individual neural cells, or networks of cells, without giving due attention to the situated task and behaviour of the organism that such neural activity is supposed to subserve. Studying the properties of stomach acid molecules is supposed to help us understand digestion; studying the brain should help us understand behaviour.

One might ask – if the researchers had carried out the study as a purely behavioural experiment, would they have then been motivated to repeat it with MRI analysis? My guess is that the behavioural component would need to have been more convincing, in which case the cart may be in front of the horse on this one.

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).

Movements that cause sound are different from those that don’t

Research spotlight #1

Neszmélyi, B. & Horváth, J. (in press). Consequences matter: Self‐induced tones are used as feedback to optimize tone‐eliciting actions, Psychophysiology. doi: 10.1111/psyp.12845*

This paper addresses a conceptual and methodological issue in research which studies attenuated perception of sensory feedback of one’s own actions. Research has indicated that neural responses to sensations that are caused by one’s actions (e.g. the sound of a bell you press yourself) result in reduced neural activity when compared to sensations that are not self-generated (e.g. the sound of a bell you didn’t press). This idea makes intuitive sense: you are likely be more sensitive to things in your environment that you did not immediately cause to happen, since things you did cause can be anticipated. How this is studied is by recording brain EEG activity (electrical signals on the scalp) when someone makes a movement that causes a sound, subtracting the activity due to the movement itself (without sound), and comparing the result to just listening to the sound with no movement. The big assumption here, which this paper tackles, is that the muscle movements which cause sound and the same movements without auditory consequences are essentially controlled in the same way.

In the experiment reported, participants had to pinch a Force Sensing Resistor (FSR) with a pre-set amount of force. This constituted the movement of the task. After some training with a visual display to get the required amount of force right, participants then performed the task under two conditions. In one condition, their pinch was effectively sonified. When they applied the right level of force, a 1000 Hz sine tone sounded (audio-motor condition: AM). In another condition, they had to pinch the FSR without any sound feedback (motor only: M). A final condition involved listening to recordings of sounds created by their previous pinches during which they made no finger movements (audio-only: A). The AM condition always came first, while the order of the A and M conditions were varied between participants. Participants did 300 repetitions of each condition (to get good EEG data, lots of repetitions of a given event are necessary). Pinch force was recorded in the AM and M conditions, and EEG activity was recorded in all three conditions.

The first striking thing that was found in the results was that the pinch force applied differed dramatically between the condition in which pinches caused the tone (AM) versus the no-tone condition (M). Force applied was a lot lighter when the pinch produced a sound than when it didn’t. The second result of interest was that as a consequence of the differences in movements when there was an auditory consequence versus none could account for the attenuated EEG response to self-generated sounds, when applying the subtraction approach described above. While this second result is of interest to people working on the neuroscience of agency, for me the first finding is the most interesting.

The difference in force applied when expecting a tone to be caused by your action versus silent pinching suggests that auditory perceptual feedback from movement can materially alter the nature of coordination with the task at hand. When sounds feedback from movements is present, the movements change because the interaction has changed. This needs to be considered when comparing, for example, behaviour during movement sonification with non-sonified movement interactions (something I would routinely do in my own research on sonification in skill learning). It needs to be considered how the auditory feedback may not only change the way that movement is guided, but also the entire nature of the task as experienced by the agent involved (actor, learner, etc.). A shift from an experimenter’s-eye-view to a participant’s-eye-view is, as always, essential.

Another important idea which this study highlights was masterly laid out by John Dewey’s in his 1896 critique of the Reflex Arc Concept in Psychology (essentially the fixation on stimulus-response causality). In the AM condition, the tones may be the result of the pinches, but they also seem to modulate the coordination of subsequent pinch movements. Essentially, participants pinched more softly when they knew a sound would result. Thus, the sensory consequences of one action modified the control of the subsequent actions across the block of trials. Behaviour is here best characterised as an ongoing coordination between action and perception, not a set of isolated stimulus-response pairs.

A final idea that this study highlights which I want to mention is the potential folly of assuming that one can study coordination and the brain by adding and subtracting perceptual and motor elements of a task. In this study,  neural activity in the AM condition was not simply the sum of activity in A and M, as had previously been assumed. If the brain is a non-linear dynamical system (and it surely is), then the different ways that elements of a task inter-relate and affect the overall state of the system need to be very carefully considered.

Of course, there are limitations in the experiment (as there are in every individual scientific study). The sound used (1000 Hz tone) is typical of a lab-based experiment, but is frustratingly un-ecological. A more ‘pinch-relevant’ auditory consequence might have revealed further interesting motor and neural behaviours. The movement itself (pinch force) is rather limited and one-dimensional, so it is not clear how far this effect could generalise to more complex actions. Also, having the A condition after the AM condition for everyone is problematic as this might mean that neural responses to the tones in the listening condition are affected by the newly formed action-sound mapping from the previous 300 AM trials. Still, this paper did address a potentially pernicious assumption in the neural agency literature, and in so doing highlighted important concepts for thinking about auditory-motor coordination processes.

 

*If you cannot access this article, use the DOI in Sci-Hub to get it. Science should be open to everyone!