Evidence for a mechanism sensitive to the speed of cyclopean form1Part of the results reported here were presented at the 1997 ARVO meeting. Kohly, Hajdur & Regan (1997). There is a speed-sensitive cyclopean mechanism, Investigative Ophthalmology and Visual Science, 38, S906.1

Two-photon absorption occurring in photoreceptors of human eye is responsible for perception of pulsed infrared laser beams. Color of perceived light corresponds to about half of wavelength of stimulating beam. This recently discovered phenomenon is called two-photon vision. However it is yet not clear how such phenomena could impact an ophthalmic diagnosis and therefore further studies are required. In this paper we present the system that enables future psychophysical experiments to extend knowledge about two-photon vision and its diagnostic value by identifying differences between two-photon and single-photon vision. Full Text: PDF ReferencesD. A. Atchison, G. Smith, Optics of the human eye (Butterworth-Heinemann 2000) CrossRef G. Palczewska et al. "Human infrared vision is triggered by two-photon chromophore isomerization", Proceedings of the National Academy of Sciences 111, 1428 (2014). CrossRef P. Artal, S. Manzanera, K. Komar, A. Gambín-Regadera, M. Wojtkowski, "Visual acuity in two-photon infrared vision", Optica 4, 1488 (2017). CrossRef K. Komar et al. "Posterior Eye Shape Measurement With Retinal OCT Compared to MRI", Investigative Ophthalmology & Visual Science 57, 196 (2016). CrossRef K. Komar et al. "Two-photon visual sensitivity of human cones - a psychophysical study", Investigative Ophthalmology & Visual Science 59, 4049 (2018). DirectLink S. A. Burns,R.H. Webb, Handbook of optics 28 (New York, McGraw Hill 1994) DirectLink R. W. Nygaard, T. E. Frumkes, "Calibration of the retinal illuminance provided by maxwellian views", Vision Research (1982) CrossRef P. Melillo et al. "Pupillometric analysis for assessment of gene therapy in Leber Congenital Amaurosis patients", Biomedical engineering online 11, 40 (2012) CrossRef P. A. Stanley, A. K. Davies, "The effect of field of view size on steady-state pupil diameter", Ophthalmic and Physiological Optics, 15, 601 (1995) CrossRef S. Mathôt, "Pupil mimicry is the result of brightness perception of the iris and pupil" Journal of Cognition 1 (2018) CrossRef M. M. Thomas, T. D. Lamb, "Light adaptation and dark adaptation of human rod photoreceptors measured from the a‐wave of the electroretinogram", The Journal of physiology 518, 479 (1999) CrossRef

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Environmental Pitch and Three Types of Pointing

Perception ◽

10.1068/v970192 ◽

1997 ◽

Vol 26 (1_suppl) ◽

pp. 373-373

Author(s):

A E Stoper

Keyword(s):

Pitch Angle ◽

Sagittal Plane ◽

Type I ◽

Viewing Distance ◽

Type Ii ◽

Investigative Ophthalmology ◽

Manual Task ◽

Pointing Errors ◽

Visual Science ◽

The Right

Many studies have shown that large errors are made when setting a target (T) to visually perceived eye level (VPEL) in a pitched environmental surround. The error in judgement of VPEL is typically about 50% of the environmental pitch angle. An observer can, however, point to the level of the target (T) with much smaller errors (eg Stoper et al, 1992 Bulletin of the Psychonomic Society30 439, found a shift of pointing of only 4% of the environmental pitch). These small pointing errors are found when the observer reaches out with an unseen hand and touches the surface on which T is presented. We call this ‘type I pointing’. If longer distances (183 cm) are used the observer must walk (with closed eyes, as in ‘pin the tail on the donkey’) in order to touch the surface on which T is presented. We call this ‘type II pointing’; it results in much larger errors, approaching in angular magnitude the errors in judgement of VPEL. In the present experiments the observer indicated the level of T by touching a point on a unseen pole which was just to the right of the observer's eyes, and thus separated from T by the viewing distance [as in the ‘manual task’ used to judge apparent height by Stoper and Bautista (1992 Investigative Ophthalmology and Visual Science, Supplement33 962)]. We call this ‘type III pointing’. This method, for both long and short distances, produced large errors similar in magnitude to those of type II pointing. These results are explained by the assumptions that environmental pitch causes an error in the judgement of the apparent horizontal in the sagittal plane (sagittal apparent horizontal; SAH) and that SAH is used in pointing of types II and III, but not of type I.

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