Involuntary postural responses of users as input to Attentive Computing Systems: An investigation on head movements

Automatic motor or involuntary postural behaviors of users have been receiving an increasing interest in recent years, as unobtrusive measures of cognitive states. In this paper, we investigate the involuntary postural responses of seated users derived from their cognitive changes as input for Attentive Computing Systems. The paper first introduces seated posture, its advantages for cognitive state assessment and connections with cognitive states and, related studies in order to provide a research background for this emerging area of research. We then focus on head posture of seated users and examine the involuntary head movements correlated with task engagement and changing task difficulty through an experiment conducted using a display-oriented cognitive task with changing difficulties. The experiment included 31 participants. Based on different measures, head response and speed, data gathered from user studies were analyzed. Repeated measures Analysis of Variances revealed that head response and speed could serve as cognitive engagement measures. The results indicated that participants get closer to a computer display and became more stationary when they were engaged in a task. The task difficulty analysis results, conversely, partially fulfilled our initial expectations. Head response and speed exhibited limited sensitive behaviors as task difficulties changed.

► Posture is a multidimensional construct that has significant potential for Attentive Computing Systems.
► Involuntary postural responses of users can serve as unobtrusive measures of cognitive state.
► We investigate the effects of task engagement and changing task difficulty on head movements.
► As participants engage in a task they get close to display and become more stationary.
► The sensitivity of head movements to task difficulty is limited, suggested as a future work.