Color Dynamics of the Pupil

Kohn, Michael; Clynes, Manfred

doi:10.1111/j.1749-6632.1969.tb14024.x

Cited by 79 publications

(44 citation statements)

References 14 publications

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“…Changes in the colour (Barbur 1991;Kohn & Clynes 1969;Saini & Cohen 1979;Young & Alpern 1980), spatial structure (Barbur & Forsyth 1986;Slooter & van Norren 1980;Ukai 1985) and movement (Barbur et al 1992a) of visual stimuli can bring about transient constrictions of the pupil, even when they cause no overall change in, or actually reduce, average retinal illuminance. Such transient constrictions are absent or greatly reduced in people with damage to primary visual cortex (Barbur 1995).…”

Section: Introductionmentioning

confidence: 99%

Visual processing levels revealed by response latencies to changes in different visual attributes

Barbur

Wolf

Lennie

1998

Proc. R. Soc. Lond. B

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Visual latencies, and their variation with stimulus attributes, can provide information about the level in the visual system at which di¡erent attributes of the image are analysed, and decisions about them made. A change in the colour, structure or movement of a visual stimulus brings about a highly reproducible transient constriction of the pupil that probably depends on visual cortical mechanisms. We measured this transient response to changes in several attributes of visual stimuli, and also measured manual reaction times to the same stimulus changes. Through analysis of latencies, we hoped to establish whether changes in di¡erent stimulus attributes were processed by mechanisms at the same or di¡erent levels in the visual pathway. Pupil responses to a change in spatial structure or colour are almost identical, but both are ca. 40 ms slower than those to a change in light £ux, which are thought to depend largely on subcortical pathways. Manual reaction times to a change in spatial structure or colour, or to the onset of coherent movement, di¡er reliably, and all are longer than the reaction time to a change in light £ux. On average, observers take 184 ms to detect a change in light £ux, 6 ms more to detect the onset of a grating, 30 ms more to detect a change in colour, and 37 ms more to detect the onset of coherent motion. The pattern of latency variation for pupil responses and reaction times suggests that the mechanisms that trigger the responses lie at di¡erent levels in cortex. Given our present knowledge of visual cortical organization, the long reaction time to the change in motion is surprising. The range of reaction times across di¡erent stimuli is consistent with decisions about the onset of a grating being made in V1 and decisions about the change in colour or change in motion being made in V4.

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Section: Introductionmentioning

confidence: 99%

Visual processing levels revealed by response latencies to changes in different visual attributes

Barbur

Wolf

Lennie

1998

Proc. R. Soc. Lond. B

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“…The constriction and dilation of the pupils is evoked by changes in the ambient luminance. However, in addition to changes in retinal illuminance, the response of the pupils to visual stimuli can also be determined by factors such as cognition ) and changes in stimulus colour (Alpern & Campbell 1962;Kohn & Clynes 1969;Young & Alpern 1980;Krastel et al 1985;Barbur et al 1992Barbur et al , 1998Young et al 1993;Kimura & Young 1995, 1996Gamlin et al 1998).…”

Section: Introductionmentioning

confidence: 99%

A linear chromatic mechanism drives the pupillary response

Tsujimura

Wolffsohn

Gilmartin

2001

Proc. R. Soc. Lond. B

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Previous studies have shown that a chromatic mechanism can drive pupil responses. The aim of this research was to clarify whether a linear or nonlinear chromatic mechanism drives pupillary responses by using test stimuli of various colours that are de¢ned in cone contrast space. The pupil and accommodation responses evoked by these test stimuli were continuously and simultaneously objectively measured by photorefraction. The results with isochromatic and isoluminant stimuli showed that the accommodative level remained approximately constant (5 0.25 D change in mean level) even when the concurrent pupillary response was large (ca. 0.30 mm). The pupillary response to an isoluminant grating was sustained, delayed (by ca. 60 ms) and larger in amplitude than that for a isochromatic uniform stimulus, which supports previous work suggesting that the chromatic mechanism contributes to the pupillary response. In a second experiment, selected chromatic test gratings were used and isoresponse contours in cone contrast space were obtained. The results showed that the isoresponse contour in cone contrast space is well described (r 2 0.99) by a straight line with a positive slope. The results indicate that a jL7Mj linear chromatic mechanism, whereby a signal from the long wavelength cone is subtracted from that of the middle wavelength cone and vice versa, drives pupillary responses.

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“…A transient constriction of the pupil diameter is elicited by interchanges of monochromatic light (6) or the onset of chromatic information when the associated luminance contributions are minimized (7). In random dot patterns, a brief episode of coherent dot movement can also lead to a transient pupil response (8).…”

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confidence: 99%

Pupil response as a predictor of blindsight in hemianopia

Sahraie

Trevethan

MacLeod

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Significance The paper follows up the suggestion that pupillometry may reveal the presence of residual visual function of which subjects are unaware (blindsight) in the field defects caused by visual cortex lesions. In a group of 19 subjects with hemi-field cortical blindness, the pupil responses in the majority matched the psychophysical findings for the sensitive spatial frequencies, indicating that it is useful to carry out pupillometry in cortical blind fields as a predictor of intact visual psychophysical function for further rehabilitation procedures.

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Color Dynamics of the Pupil

Cited by 79 publications

References 14 publications

Visual processing levels revealed by response latencies to changes in different visual attributes

Visual processing levels revealed by response latencies to changes in different visual attributes

A linear chromatic mechanism drives the pupillary response

Pupil response as a predictor of blindsight in hemianopia

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