The Spatial and Temporal Structure of Reach-to-Grasp Movements

This post is part of my current series where I am developing a research programme to formally connect affordances and motor abundance analyses (see the intro post here). The first thing I need is a task that has a formal affordance analysis; my chosen task is reaching-to-grasp (sometimes called prehension). I'm pivoting to this task from throwing for a few reasons. First, I need a simpler task. The logistics of data collection and analysis for throwing tasks are large and I just don't have the resources right now; I do have the kit for these studies. Second, I want to expand my own skill set to a new domain, and reach-to-grasp is another venerable topic. Finally, it means I get to spend time really grappling with other work by Geoff Bingham, who was my PhD supervisor and who remains the person who's work I admire the most. 

This post is about the basic form of the reach-to-grasp movements studied in the lab, what some of the key measures are, and the fact these are sensitive to task demands (suggesting they are emerging from an active perception-action loop). In the next post I will work through the initial task analysis that leads us to candidate affordance properties. 

Some Thoughts on Handwriting

A few years a go I reviewed a paper about a method, the sigma-lognormal model, to quantitatively assess handwriting (Plamondon et al, 2013). I was interested because I had in the past worked with children with developmental coordination disorder on a project developing ways to take better movement assessment out of the lab and into the clinic, and handwriting is a) something kids and their parents value and want to improve but b) is a beast to quantify. 

Réjean Plamondon kindly sent me his analysis software to play with, and I have three experiments worth of data I am currently analysing in an effort to assess whether it can help me find what I want. Here I'll briefly review the model, the experiments and some lessons I've learned training myself to write with my nondominant right hand.