From the simple to the complex: A handy guide to movements

Chris Harrison, Assistant Professor in Human-Computer Interaction Institute (HCII), Carnegie Mellon, and Gierad Laput, HCII PhD student, found that studying the various hand activities brought them to broadly segregating them into three types:

Atomic hand activities: These are hand movement that cannot be broken down into distinct stages. For example, wiping, scratching.

Examples of everyday atomic hand movements are:

Compound: These are atomic hand activities that have multiple stages of movements to achieve a single purpose, such as eating and cooking. For example, the purpose of cooking in the which the hands engage is a combination of many atomic hand movements such as chopping or peeling vegetables.

Examples of everyday compound hand movements are:

Ambiguous: These hand activities could involve diverse appoaches. For example, when the hands open a bottle, they can either twist the cap off or use a bottle opener, which involve different movements though towards the same goal.

Examples of everyday ambiguous hand movements are:

(Source: Sensing Fine-Grained Hand Activity with Smartwatches Gierad Laput and Chris Harrison, Carnegie Mellon University, Human-Computer Interaction Institute (HCII), 2019.)