Awareness of Being Tested and Its Effect on Reading Behaviour.

The Hawthorne effect, a behaviour change in response to the awareness of being tested, during the execution of an eye-tracking battery for the detection of mild cognitive impairments (MCI) has not yet been considered. The present work has a twofold aim: (i) to search for the potential differences between eye-tracking signals recorded during the reading in two different experimental conditions, when subjects are aware of being tested or not and (ii) to determine which of the two signals best predicts cognitive impairments (CI). The reading behaviour from 94 subjects was collected, comprised of 53 healthy controls (HE) and 43 CI subjects. For each subject, we recorded their reading behaviour during three different tasks and machine learning algorithms were used to distinguish between the eye-tracking signal in case people are aware/are not aware of being tested. The results suggested that only the HE subjects are affected by the Hawthorne effect (with an AUC of 80%), so the best way to distinguish between HE and CI participants is when the subjects are not aware of being tested.