Probability summation and regional variation in contrast sensitivity across the visual field

Robson, J. G.; Graham, Norma

doi:10.1016/0042-6989(81)90169-3

Cited by 600 publications

(396 citation statements)

References 16 publications

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“…5 indicate that contrast thresholds in the periphery continue to decrease with increasing number of grating cycles up to as much as 64 cycles. Robson and Graham (1981) obtained the same result. They were able to show that their results for both fovea and periphery could be expcplained by probability summation over the full spatial extent of the stimulus, with a probability summation exponent of 3.5.…”

Section: Discussionsupporting

confidence: 64%

“…Note that the curves marked with triangles and squares have been shifted downwards by factors of 2 and 4 respectively. The dashed lines indicate a slope of -lj3.5, corresponding to the probability summation exponent of 3.5 which Robson and Graham (1981) used to fit their results from similar experiments. Our results are in good agreement with those of Robson and Graham.…”

Section: Resultsmentioning

confidence: 99%

“…To ensure that the stimuli were presented in an approximately homogeneous part of the retina we used vertical strips of horizontal grating having widths of 2 and 4deg at eccentricities of 12 and 18 deg respectively. [A similar stimulus con~guration was used by Robson and Graham (1981) for measuring peripheral spatial summation in a threshold contrast task.] The height of the grating (and thus the number of grating cycles contained in it) was varied.…”

Section: For An Em-gratingmentioning

confidence: 99%

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The sensitivity of the peripheral visual system to amplitude-modulation and frequency-modulation of sine-wave patterns

1984

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Abstract-The det~tabi~~ty ofamp~itud~ modulation and spat% frequency modulation ofsuprat~resh~~ld sine-wave gratings was measured at retinal eccentricities ranging from 0 to 30 deg. The main conclusions to be drawn from the experimental results are: (I) for this visual task it is not possible to bring peripherai sensitivity to the same level as fovea1 sensitivity by scaling the stimuli with the inverse of the cortical magnification factor M. (2) Increasing the number of cycles in the carrier grating improves modulation detectability. For gratings in the periphery this holds up to the largest stimulus size used (6-l cyclrs). In earlier investigations it has been shown that for central vision the improvement ends at about I6 cycles.

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Section: Discussionsupporting

confidence: 64%

Section: Resultsmentioning

confidence: 99%

Section: For An Em-gratingmentioning

confidence: 99%

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The sensitivity of the peripheral visual system to amplitude-modulation and frequency-modulation of sine-wave patterns

1984

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“…Robson and Graham (1981) reported a log-log slope, s, of threshold vs number of bars of -0.29 for gratings of various spatial frequencies presented in a region of uniform sensitivity. We may summarize these estimates of the log-log slope for s~mation by the corresponding value of B = -l/s = 3.5 f 0.8.…”

Section: Summationmentioning

confidence: 99%

On the relation between summation and facilitation

Pelli

1987

Vision Research

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“…As we mentioned earlier, the visual cortex in the HVS can be thought of as a spatial frequency filter-bank with octave spacing of subbands in radial frequency, and angular bands of roughly 30 degree spacing. The presence of a signal component in one of these subbands will raise the detection threshold for other signal components in the same subband [61][62][63] or even neighboring subbands.…”

Section: Contrast Maskingmentioning

confidence: 99%