The role of pupil mimicry in the establishment of trust in clinically anxious and depressed patients
Humans cooperate with, and extend trust to both familiar and unfamiliar others, enabling groups and institutions to function and prosper. To avoid betrayal, exploitation, or subordination, humans must sometimes withhold trust. Assessments of whether someone can be trusted can be based on effortful scrutiny of another’s moral status, on the availability of sanctions for non-cooperation, on the possibility of reciprocity, but, they can also be made within an eyeblink, without much thinking.

In recent research in collaboration with Dr. de Dreu and Dr. Fischer I showed that pupillary changes can reflect affective states and that they are picked up by observers, who unconsciously synchronize; pupils dilate when someone else’s pupils dilate, and constrict when those of the observed shrink. Moreover, pupil-mimicry between people helps to build trust. Preliminary functional magnetic resonance imaging (fMRI) data suggests the involvement of the so-called Theory of Mind Network.

With aid of the EASP Extraordinary grant, I was able to initiate a collaborative project with PD Dr. Koelkebeck from the Muenster University Hospital. The aim of this project is to investigate these phenomena further in clinically depressed and anxious patients. From these patients, it was already known that they are generally very low on trust. This was also confirmed in a trust game we conducted in depressed patients. We believe that testing pupil mimicry and its linkage to trust is especially useful in these patients because these are very basic, unconscious phenomena that cannot be faked or manipulated.

During my recent visit at the clinic, I helped setting up an eye-tracking system in the MRI scanner and implement the experimental paradigm in that setting so that we can compare their neural activation patterns with healthy controls, with a specific focus on the Theory of Mind Network. The project is now ready to go and we have started with recruiting patients, aiming for 20 depressed patients, 20 anxious patients, and 20 controls. The results are to be expected in autumn 2016.