Effect of Target Size, Luminance, and Color on Monocular Fixation*

Steinman, Robert M.

doi:10.1364/josa.55.001158

Cited by 297 publications

(214 citation statements)

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“…The overall mean vector magnitude for the shifts of the direction of the line of sight was 3.6 min of arc for 5 R.S. and 4.4 min of arc for S G. H. Shifts of the average direction of the line of sight of this magnitude would be expected even if the fixation stimulus were a diffraction-limited point (Steinman, 1965).…”

Section: Fixation Is Not Influenced By the Shape Of A Visual Displaymentioning

confidence: 82%

“…This comparison was made only if the difference between the two trials in which the S fixated the point was less than 4 min of arc on both meridians. This criterion was chosen on the basis of Steinman's (1965) measurements, which showed that deviations in mean eye position of this magnitude are to be expected when sources of variability due to stimulus parameters are removed. This permitted 203 comparisons to be made for S G.H.…”

Section: Fixation Is Not Influenced By the Shape Of A Visual Displaymentioning

confidence: 99%

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Simple forms and fluctuations of the line of sight: Implications for motor theories of form processing

Murphy

Haddad

Stelnman

1974

Perception & Psychophysics

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A contact lens optical lever was used to measure two-dimensional fixation characteristics when experienced Ss fixated at various positions within simple forms small enough to fall entirely on the foveal floor ( < 80 min). Fixation stability and the average direction of the line of sight were not markedly or systematically affected by the shape of the fixation stimulus. Similar results were obtained when all saccades were suppressed and the line of sight maintained exclusively by means of slow control. These results cast doubt on motor theories of form perception.Eye movements or tendencies toward eye movements have been proposed as the explanatory principle in motor theories of visual illusions and form perception for more than a century (Lotze, 1852; Wundt, 1910;Hebb, 1949;Festinger, 1971). According to these theories, visual perception of form is based on the pattern of oculomotor responses or, more recently, the programming of these responses. The particular eye-movement pattern is determined by the shape of the retinal stimulus. Similarly, illusions are explained by reference to tendencies to eye movements that produce an incongruity between the pattern of oculomotor responses made or programmed and the pattern of retinal stimulation. Despite theorizing and much speculation, very little is actually known about the relationship between tine-grain characteristics of the human oculomotor pattern and the configuration of a visually presented stimulus. Detailed study of this relationship is essential not only for an evaluation of motor theories of form processing but also for complete descriptions of human oculomotor characteristics. The present experiments examine this relationship. METHOD Eye-Movement Recording and AnalysisAn electronic contact-lens optical lever was used to make continuous two-dimensional recordings of eye position. A detailed description of the apparatus has been reported by Haddad and Steinman (\973). As used in the present experiments, the recording limits of this instrument were I deg of arc on both meridians. permitting resolution of eye position to approximately 3 sec of arc. For each trial, the mean and standard deviation of eye position voltages on the horizontal and vertical meridians were calculated on-line by a special-purpose analog device. The time constants of the integrating circuits in this device were chosen empirically such that means and standard deviations estimated by the device from a random sample of fixation trials for each S matched. to within 1%, means and standard deviations calculated from a random sample of brief eye-position voltages taken from the same trials. The output of thc analog device was digitized and printed out at the end of each trial. StimuliThe stimuli were high-contrast (>900/0) photographic transparencies of computer-generated and drawn forms. The transparencies were shown in rear projection on a diffusing screen (Callier's coefficient = 4.6) that had no visible texture at the viewing distance of 2 m. A pellicle was placed in the S's line of sight...

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Section: Fixation Is Not Influenced By the Shape Of A Visual Displaymentioning

confidence: 82%

Section: Fixation Is Not Influenced By the Shape Of A Visual Displaymentioning

confidence: 99%

Simple forms and fluctuations of the line of sight: Implications for motor theories of form processing

Murphy

Haddad

Stelnman

1974

Perception & Psychophysics

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“…deviation in the direction of gaze as measured over sustained (half a second or longer) attempts at fixation is small, estimated to be between 2 and 4 min arc (e.g. Steinman, 1965;Ditchbum, 1973). Snodderly and Kurtz (1985) estimated between-trial variability in the direction of gaze by measuring a final eye position as the mean of samples taken every 5 msec in the last 200 msec of trials lasting many seconds.…”

Section: Specijic Aspects Of the Modelmentioning

confidence: 99%

The relative numbers of long-wavelength-sensitive to middle-wavelength-sensitive cones in the human fovea centralis

1989

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Abstrset-The determination of the relative numbers of different cone types in the human retina is fundamental to our understanding of visual sensitivity and color vision; yet direct measurements which provide this basic information have not previously been made for ail cone types. Here we present a model which links the detection of a test light of small dimension to the number of cones contributing to detecfon of the light. We selectively isolated either the long-wavelength-sensitive (L) or the middle-wavelengthsensitive (M) cones, by choosing combinations of wavelengths of adapting backgrounds and tests to favor detection by the cone class of interest. Our model was applied to the detection functions measured for six color normal observers to obtain estimates of the relative numbers of L to M cones. Our estimates ranged between 1.46 and 2.36 for our observers with a mean value near two L cones for every M cone in human fovea centralis. ConesHuman fovea centralis Relative numbers of L to M cones ~RODU~ONThe determination of the relative numbers of different cone types in the retina is fundamental to our understanding of human visual sensitivity and color vision, and this information would be required for any quantitative models of human vision. Direct measurements which provide this basic information have not been previously made for all cone types. There continues to be a gratifying convergence of psychophysically derived evidence from humans ~Williams et al., 1981) and anatomically derived evidence from baboon (Marc and Sperling, 1977), macaque (deMonasterio et al., 1985), and human (Ahnelt et al., 1987) on the numerosity and distribution of the shortwavelength-sensitive (S) cones in the primate retina.In the cases of the long-wavelength-sensitive (L) and middle-wavelength-sensitive (M) cones, there are no previous direct psychophysical measurements from which the relative numbers of L and M cones can be derived, and estimates based on various indirect means vary widely. To our knowledge, DeVries (1946DeVries ( , 1948 was the first to suggest that the individual variability in luminosity functions could be related to individual variability in the relative numbers of different cone types. Rushton and Baker (1964) subsequently reported that retinal densitometric measurements yielding the density of M and L cone pigments could be correlated to the flicker photometric matches between red and green lights made by their observers. Rushton and Baker's estimates, based on densitometric measurements, of the relative numbers of L to M cones in normal trichromatic observers spanned a wide range of three times more L as compared to M cones to one third as many L as compared to h4 cones. Another approach has been based on estimates deriving from curve fits required to make various sets of psychophysical data consistent one to another. Examples of this kind of analysis include Walraven's (1974) and Smith and Pokorny's (1975) estimates based on fits of the cone primaries to the luminosity function; Vos and Walraven's (1971)...

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“…A visual function reportedly not affected by luminance is the discrimination of a target's meridian in the visual field, which Grant (1955a, 1955b) found to be as good at the light detection threshold as at much higher luminances. Oculomotor functions such as fixation, smooth tracking, and optokinetic nystagmus have been reported also to survive substantial reductions of target luminance with little or no performance decrement (Boyce, 1967;Steinman, 1965;Valciukas, 1972;Winterson & Steinman, 1978).The significance of Leibowitz's findings is their implication that the mechanismts) by which target meridian is determined differ fundamentally from mechanisms that process other aspects of visual stimuli, which depend importantly upon stimulus luminance. Because of this important implication for how different aspects of the visual scene may be processed, we sought to replicate and extend the results of the Leibowitz et al studies, using a task complementary to theirs.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Precision and accuracy of oculocentric direction for targets of different luminances

Bedell

Johnson

Barbeito

1985

Perception & Psychophysics

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The precision and accuracy of specifying oculocentric directions were assessed by successively partitioning an 8.3 0 space in the right field into a series of perceptually equal fractional spaces and then matching each partitioning target's direction in the left field. Three observers performed this task for four target luminances, ranging from 0.04 to 43 cd/m", The results show that luminance has virtually no effect on either the precision or accuracy of spatial partitioning; essentially no effect was obtained even when, for one observer, target luminance was reduced to nearly the absolute threshold. We interpret these data in terms of oculocentric direction's role in mediating visual behaviors.That visual functioning is reduced when illumination is reduced has been documented and quantified in over a century of scientific research. For example, resolution of fine detail and identification of form (Koenig, 1897, cited in Helmholtz, 1924/1925, 1925Schlaer, 1937), discrimination of color (Weale, 1951), and detection of temporal and spatial luminance contrast (Kelly, 1961;van Nes & Bouman, 1967) are all impaired substantially as the luminance of targets is decreased. A visual function reportedly not affected by luminance is the discrimination of a target's meridian in the visual field, which Grant (1955a, 1955b) found to be as good at the light detection threshold as at much higher luminances. Oculomotor functions such as fixation, smooth tracking, and optokinetic nystagmus have been reported also to survive substantial reductions of target luminance with little or no performance decrement (Boyce, 1967;Steinman, 1965;Valciukas, 1972;Winterson & Steinman, 1978).The significance of Leibowitz's findings is their implication that the mechanismts) by which target meridian is determined differ fundamentally from mechanisms that process other aspects of visual stimuli, which depend importantly upon stimulus luminance. Because of this important implication for how different aspects of the visual scene may be processed, we sought to replicate and extend the results of the Leibowitz et al. studies, using a task complementary to theirs. Specifically, we investigated the effect of target luminance on observers' precision and accuracy in specifying the oculocentric direction of targets with respect to the fixation locus and other visual targets along a single (the horizontal) meridian of the field. Precision is defined as the fineness or sensitivity of direcThis work was supported by National Eye Institute Research Grant EY 03694 to Merton C. F1om. We thank Stan Klein for the program used to psychometrically fit our data and Gale Pedersen for assistance in analyzing the results.The authors' mailing address is: College of Optometry, University of Houston, University Park, Houston, TX 77004. tion judgments; imprecision is measured as the variability of these judgments. Accuracy refers to how closely judgments of direction agree with physical directions; inaccuracy is determined by the magnitude of observers' constant errors....

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Effect of Target Size, Luminance, and Color on Monocular Fixation*

Cited by 297 publications

References 9 publications

Simple forms and fluctuations of the line of sight: Implications for motor theories of form processing

Simple forms and fluctuations of the line of sight: Implications for motor theories of form processing

The relative numbers of long-wavelength-sensitive to middle-wavelength-sensitive cones in the human fovea centralis

Precision and accuracy of oculocentric direction for targets of different luminances

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