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The effect of mental effort on open- and closed-loop accommodation
B Winn1, B Gilmartin, L C Mortimer
1Department of Vision Sciences, Aston University, Birmingham, UK.
Summary
Mental effort impacts visual accommodation. A stimulus-dependent task significantly shifted accommodation, while a stimulus-independent task did not, suggesting specific cognitive processes influence eye focus.
Area of Science:
- Ophthalmology
- Cognitive Neuroscience
- Human Factors
Background:
- Visual accommodation is influenced by both optical and non-optical factors.
- Mental effort's effect on accommodation is not fully understood due to varied research designs.
Purpose of the Study:
- To investigate how different levels of mental activity affect the accommodative response under open- and closed-loop conditions.
- To clarify the mechanisms by which mental effort influences steady-state accommodation.
Main Methods:
- Ten emmetropic subjects viewed a near target under monocular conditions.
- Accommodation was measured using an infrared optometer.
- Three mental tasks were employed: passive reading, stimulus-dependent task (SDT), and stimulus-independent task (SIT).
- Open-loop measurements were obtained using a pinhole.
Main Results:
- Under closed-loop conditions, passive viewing resulted in a mean accommodation of +3.08 D.
- The SDT induced a significant accommodative shift of +0.17 D.
- The SIT resulted in a non-significant shift of -0.05 D compared to passive viewing.
Conclusions:
- Mental effort, particularly when stimulus-dependent, can significantly alter accommodative responses.
- The findings suggest that cognitive engagement plays a role in modulating visual accommodation.
- Further research is needed to fully elucidate the complex interplay between mental effort and the visual system.