Interactions of visual and cognitive stress.

BACKGROUND The objective of this research is to assess the ocular and muscular response to long-duration reading under different visual and cognitive difficulty levels. METHODS Thirty-five subjects, with 20/20 vision and without history of ocular pathology or cognitive deficits, participated in the study. Subjects read under different visual and cognitive difficulty levels for 6 (30-minute) conditions. Upper and lower orbicularis oculi, frontalis, and trapezius muscle activities were recorded using surface electromyography (EMG). Aperture size, pupil diameter, and pulse rate of the subjects were recorded with a video camera, pulse meter, and ISCAN eye tracker (ISCAN Inc.), respectively. RESULTS The results show that the texts read with a refractive error caused increased orbicularis oculi EMG power and reduced aperture size (P < 0.001). There was no statistically significant difference between the conditions for pulse rate, pupil diameter, or EMG activity of the frontalis and trapezius muscles with either visual or cognitive stress presented in this experiment. CONCLUSION Visual stress experienced due to reading under an induced refractive error is potentially mediated by a local mechanism, different from the mechanism underlying reading under low contrast or high cognitive demand.

[1]  J. Sheedy,et al.  Is all Asthenopia the Same? , 2003, Optometry and vision science : official publication of the American Academy of Optometry.

[2]  J. Sheedy,et al.  Eyelid Squint Response to Asthenopia-Inducing Conditions , 2007, Optometry and vision science : official publication of the American Academy of Optometry.

[3]  Wayne B. Hunter,et al.  Iridovirus in the root weevil Diaprepes abbreviatus , 2003 .

[4]  Ian L. Bailey,et al.  An Objective Measure of Discomfort Glare , 1994 .

[5]  Mikael Forsman,et al.  Consistency in physiological stress responses and electromyographic activity during induced stress exposure in women and men , 2004, Integrative physiological and behavioral science : the official journal of the Pavlovian Society.

[6]  J E Sheedy,et al.  Myofascial trigger point development from visual and postural stressors during computer work. , 2006, Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology.

[7]  O Hidaka,et al.  Mental Stress-induced Physiological Changes in the Human Masseter Muscle , 2004, Journal of dental research.

[8]  Á. Esteban,et al.  Eyelid movements in health and disease. The supranuclear impairment of the palpebral motility , 2004, Neurophysiologie Clinique/Clinical Neurophysiology.

[9]  R. Westgaard,et al.  EMG activity and pain development in fibromyalgia patients exposed to mental stress of long duration. , 2001, Scandinavian journal of rheumatology.

[10]  Mihaly Csikszentmihalyi,et al.  Television and the Rest of Life: A Systematic Comparison of Subjective Experience , 1981 .

[11]  James E. Sheedy,et al.  VDTs and vision complaints: a survey , 1992 .

[12]  JAMES E. SHEEDY,et al.  What are the Visual Benefits of Eyelid Squinting? , 2003, Optometry and vision science : official publication of the American Academy of Optometry.

[13]  N. Schenker,et al.  Overlapping confidence intervals or standard error intervals: What do they mean in terms of statistical significance? , 2003, Journal of insect science.

[14]  Manfred Velden,et al.  The pupillary response to mental overload , 1977 .

[15]  P. Hassmén,et al.  Psychophysiological stress and emg activity of the trapezius muscle , 1994, International journal of behavioral medicine.

[16]  Yu-Chi Tai,et al.  Objective Measurements of Lower-Level Visual Stress , 2007, Optometry and vision science : official publication of the American Academy of Optometry.

[17]  Martha E. Crosby,et al.  Assessing Cognitive Load with Physiological Sensors , 2005, Proceedings of the 38th Annual Hawaii International Conference on System Sciences.

[18]  Jørgen Skotte,et al.  Stress reactions to cognitively demanding tasks and open-plan office noise , 2009, International archives of occupational and environmental health.

[19]  J. Stern,et al.  Blinks as an index of cognitive activity during reading , 1991, Integrative physiological and behavioral science : the official journal of the Pavlovian Society.

[20]  Robert R. Whelan.  Neuroimaging of cognitive load in instructional multimedia , 2007 .

[21]  J. Sheedy,et al.  Blink Rate Decreases With Eyelid Squint , 2005, Optometry and vision science : official publication of the American Academy of Optometry.