This research describes an approach to objective assessment of mental workload, by analyzing differences in pupil diameter and several aspects of eye movement (fixation time, saccade distance, and saccade speed) under different levels of mental workload. In an experiment, these aspects were measured by an eye-tracking device to examine whether these are indeed indicators for mental workload. Pu...

We measured apparent accommodation in 42 pseudophakic eyes (34 patients) after implantation of posterior chamber intraocular lenses. The mean apparent accommodation was 2.03 +/- 1.03 diopters. The mean accommodative power of 16 phakic eyes used as controls was 2.91 +/- 1.29 diopters. The diameter of the pupil appeared to be the most important factor in apparent accommodation--the smaller the pu...

In a driving simulator study, we explore the feasibility of using pupil diameter to estimate how the cognitive load of the driver changes during a spoken dialogue with a remote conversant. We confirm that it is feasible to use pupil diameter to differentiate between parts of the dialogue that increase the cognitive load of the driver, and those that decrease it. Our long term goal is to build a...

Pupillary measures have been linked to arousal and attention as well as activity in the brainstem's locus coeruleus norepinephrine (LC-NE) system. Similarly, there is evidence that evoked EEG responses, such as the P3, might have LC-NE activity as their basis. Since it is not feasible to record electrophysiological data directly from the LC in humans due to its location in the brainstem, an ope...

This paper outlines the development and hardware software integration of an instrumental setup designed towards the real-time assessment of the affective status of a computer user. This assessment is based on the measurement and digital signal analysis of three physiological variables that reflect dynamic changes of the Autonomic Nervous System (ANS): Blood Volume Pulse (BVP) measured with an i...

The pupil controls the amount of light entering the eye. We have examined both the time course for the development of the light reflex and pupil diameter before and after this event in 50 neonates. The pupillary light reflex was absent in all neonates of less than 30 weeks' gestational age, it gradually developed from this age and by 35 weeks it was present in all. Several possible mechanisms t...

Motor learning has traditionally been associated with the concept of automaticity. Automaticity refers to the reduction of the cognitive effort required to perform a motor task, as learning progresses. However, there is little detailed consensus in the literature on what the process of automatization actually involves. We measured tracking performance in two groups of participants while either ...

We evaluated the hypothesis that individual differences in working memory capacity are explained by variation in mental effort, persons with low capacity exerting less effort than persons with high capacity. Groups previously rated high and low in working memory capacity performed the reading span task under three levels of incentive. The effort hypothesis holds that low span subjects exert les...

Mental fatigue is often characterized by reduced motivation for effortful activity and impaired task performance. We used subjective, behavioral (performance), and psychophysiological (P3, pupil diameter) measures during an n-back task to investigate the link between mental fatigue and task disengagement. After two hours we manipulated the rewards to examine a possible reengagement effect. Anal...

We considered the influence that the Stiles-Crawford effect (SCE) has on the measurement of subjective monochromatic and transverse aberration measurements. The SCE was measured with a two channel Maxwellian-viewing system. Transverse aberrations were measured using a vernier alignment technique in three subjects, with the natural SCE operating, with the SCE neutralised by filters optically con...