Investigating the effects of mid-air haptics on the sense of agency

The sense of agency (SoA), the feeling of exerting causal influence over the environment via our own actions, extends to human-computer interaction (HCI). Recent advances in mid-air haptic technology were developed to accompany contactless hand-tracking interactions with touch sensation. An interdisciplinary principle underpins this thesis investigating effects of mid-air haptics on SoA. That is, I seek to make use of this manipulable haptic feedback for novel insights into the psychology of agency, and also hope that this research (using robust psychological methods) provides novel insights into user experience when using the technology.

In Chapter 2, the agent is situated in the virtual world where mid-air haptics are integrated. The first experiment showed the salient presence (versus absence) of mid-air haptics can increase explicit SoA. The second experiment revealed that subtly different haptic types can modulate implicit SoA. These signify differences noted in the feeling and judgement of agency and have implications for integrating mid-air haptics in virtual reality.

Chapter 3 situates the agent in the automotive context, where mid-air haptics is used in gesture-based interactions. The first experiment showed that haptic feedback strengthened SoA compared to visual feedback. A second experiment looked at mid-air haptics in a driving simulator scenario and showed that mid-air haptics increases SoA over in-vehicle infotainment compared to typically used audio feedback. These findings suggest mid-air haptics is particularly beneficial for gesture-based interactions.

A more fundamental yet distinct aspect of SoA was turned to in Chapter 4; namely the awareness of intention. Here we manipulated the predictability of receiving mid-air haptic feedback. In a first experiment we found a delayed awareness of intention under uncertainty. In a second experiment we found that this delay was as a function of the probability of haptic feedback. This supports an anticipatory mechanism for formulating intentions and may have implications for certain volitional disorders, such as schizophrenia.

In the concluding chapter, the findings are summarised and implications for psychology as well as practical HCI applications are discussed.