PURPOSE To measure the dependence of the size of the pupils of mice on steady retinal illumination. METHODS Anesthetized C57BL/6 mice aged 7 to 8 weeks were placed in a ganzfeld chamber in darkness, and in monochromatic (510 nm) and white light whose intensity was varied more than 6 log units. The pupils of the mice were photographed with an infrared video camera and recorded on videotape and...

Perceptual learning refers to the improvement of perceptual sensitivity and performance with training. In this study, we examined whether learning is accompanied by a release from mental effort on the task, leading to automatization of the learned task. For this purpose, we had subjects conduct a visual search for a target, defined by a combination of orientation and spatial frequency, while we...

Fluctuations in pupil size have been shown to reflect variations in processing demands during lexical and syntactic processing in language comprehension. An issue that has not received attention is whether pupil size also varies due to pragmatic manipulations. In two pupillometry experiments, we investigated whether pupil diameter was sensitive to increased processing demands as a result of com...

PURPOSE To prospectively compare the scotopic pupil size between emmetropes and myopes using a Colvard pupillometer. METHODS The pupil diameters of 55 normal subjects and 55 healthy myopic subjects were measured with the Colvard pupillometer in a low-light situation that simulated the level of light encountered while driving at night. RESULTS The mean (+/- SD) age of the emmetropic subjects...

Abstract— A new iris recognition and person identification technique is introduced. The method is based on tracing the Eye image boundary, using the MarrHildreth edge technique. The Eye's pupil boundary is identified, using the contour follower which is based on the chain coding method. The coordinates of the pupil's center is then recognized as the center of figure of the pupil boundary chaine...

The pupillary light response has been shown not to be a purely reflexive mechanism but to be sensitive to higher order perceptual processes, such as covert visual attention. In the present study we examined whether the pupillary light response is modulated by stimuli that are not physically present but are maintained in visual working memory. In all conditions, displays contained both bright an...

Pupillary response is associated with perceptual and cognitive loads in visual and cognitive tasks, but no quantitative link between pupil response and the task workload in visual motor tasks has been confirmed. The objective of this study is to investigate how the changes of task requirement of a visual motor task are reflected by the changes of pupil size. In the present study, a simple conti...

In this study, we evaluated the repeatability of pupil responses to colored light stimuli in healthy subjects using a prototype chromatic pupillometer. One eye of 10 healthy subjects was tested twice in the same day using monochromatic light exposure at two selected wavelengths (660 and 470 nm, intensity 300 cd/m(2)) presented continuously for 20 s. Pupil responses were recorded in real-time be...