A couple of weeks back, I started writing about a design project I'm doing as part of my MSc coursework. In the course of thinking about what makes mobile interfaces emotionally engaging, I came up with a half-baked theory that for evolutionary reasons long, languid gestures like strokes are more emotionally satisfying than the stabbing, poking motions we often use when, say, clicking buttons on touch-screens: "stroking, not poking".
I reached out to a few friends on Facebook to see if anyone could help me find some justification for this, and had a great response. A couple of publications stand out; firstly, from The Role of Gesture Types and Spatial Feedback in Haptic Communication by Rantala et al. (which Mat Helsby pointed me at):
"…support can be found for the view that interaction with haptic communication devices should resemble nonmediated interpersonal touch. Squeezing and stroking are closer to this ideal as the object of touch (i.e., the haptic device) can be understood to represent the other person and particularly his/her hand. To put it simply, stroking and squeezing the hand of another person are more common behaviours than moving (or shaking or pointing with)it."
"Preference for squeezing and stroking can be attributed to several reasons. Both methods were based on active touch interaction with the device whereas moving used an alternative approach of free-form gestures. Profound differences can be identified between these input types. Moving supported mainly a use strategy where one pointed or poked with the device, as studied by Heikkinen et al. Conversely, when squeezing and stroking, the device could be understood to be a metaphor of the recipient. This could have affected the participants’ subjective ratings as the metaphor strategy was closer to unmediated haptic communication. Furthermore, when rotating or shaking a passive object, kinaesthetic and proprioceptive information from limb movements is dominant. It could be argued that because stroking and squeezing an object stimulates one’s tactile senses (e.g., vibration caused by stroking with one’s fingertip), these two manipulation types were preferred also with active vibro-tactile feedback."
Mat also pointed me at The Handbook of Touch, which has a few choice quotes including this one:
"In addition to the decoded findings, extensive behavioural coding of the U.S. sample identified specific tactile behaviours associated with each of the emotions. For example, sympathy was associated with stroking and patting, anger was associated with hitting and squeezing, disgust was associated with a pushing motion…"