Towards Voluntary Pupil Control - Training Affective Strategies?
Jan Ehlers, Nikola Bubalo, Markus Loose, Anke Huckauf · 2015
During the past years, increasing attention is being paid to operationalize pupil dynamics for affective classification (Jacobs, 1996). Thereby it is generally assumed that pupil size displays a genuine impression of user’s cognitive state but defies any voluntary control (Loewenfeld, 1993). Based on Ekman (2008) we applied graphical feedback on pupil diameter changes to utilize mechanisms of operant conditioning to gradually enable voluntary control over pupil size. Participants underwent a training program to exert control by utilizing affective associations to expand pupil size and relaxation strategies to reduce it. As a result, more than half of the participants demonstrated to be able to increase pupil sizes relative to baseline recordings. Training effects did not show up. Furthermore, controlling influence diminishes after about ten seconds. Intentional increase of sympathetic activity seems to be subject to habituation processes that allow central inhibition of parasympathetic pathways only over a short period. Beside strategy-based factors, physiological mechanisms like baseline pupil activity may determine inter-individual differences in exerting voluntary control. In summary it can be noted that pupil-based communication in HCI extends affective monitoring and may constitute an active input channel to reliably interfere by means of simple cognitive strategies.