Marathon adaptation to spatial contrast: Saturation in sight

Magnussen, Svein; Greenlee, Mark W.

doi:10.1016/0042-6989(85)90218-4

Cited by 58 publications

(67 citation statements)

References 16 publications

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“…served in both experiments we can compare the time courses of the threshold elevation and tilt Fig. 1 [lower panel the contrast threshold elevation data for this subject are reproduced from Magnussen and Greenlee (1985). Considering the differences in stimulus patterns and test exposers in the two experiments (large field gratings vs single lines; 5 vs 1.5 set test duration) the agreement is remarkable.…”

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confidence: 69%

“…In a recent experiment (Magnussen and Greenlee, 1985) we measured the growth of the threshold elevation aftereffect well beyond the saturation point during a 3 hr adapting session, and tracked its subsequent decay. We have conducted a similar experiment on the tilt aftereffect, and are now able to compare the time-courses of the complete growth and recovery from continuous adaptation routines for these two aftereffects.…”

Section: Afterekects Saturation Psychophysicsmentioning

confidence: 99%

“…The main experimental session was modelled after Magnussen and Greenlee (1985): after completing 10 baseline settings, the subject initiated a 2-2 i hr session of continuous adaptation, interrupted by tests of aftereffect size at 10-30 min intervals. The first readings were collected after 10 min (for S.M.)…”

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Saturation of the tilt aftereffect

Greenlee

Magnussen

1987

Vision Research

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Abatraet-The tilt aftereffect increases as a logarithmic function of adapting time, reaches saturation after approx 1 hr and decays on a symmetric, logarithmic time-course. This is similar to the time-course of contrast threshold elevation, suggesting that threshold and suprathreshold aftereffects are based on similar type of adaptation processes. AftereKects Saturation PsychophysicsAn economical theory of spatial aftereffects nussen and Johnsen (1986). The adapting and suggests that the variety of perceptual changes test patterns, shown in a scaled-down representhat result from prolonged inspection of high-tation in inset to Fig. 1, were black lines contrast patterns are based on adaptation in presented on an approx 70cd/m2 background similar or closely analogous mechanisms. Thus with a line/background contrast of approx. 0.9. a common basis might be found for the orienChanges in perceived orientation were measured tation and spatial frequency selective elevation by setting the orientation of a micrometerof contrast thresholds, the reduction of apparcontrolled comparison line C to match a physient contrast of suprathreshold stimuli, and cally vertical test line T, and the tilt aftereffect the shifts in perceived spatial frequency and is the difference between the mean settings beorientation (Braddick et al., 1978). However, fore and after adapting to a 12 deg clockwise discrepancies between aftereffects have been tilted adapting line A. The test pattern was occasionally noted (e.g. Magnussen and Kur-presented in 1.0 set exposures, interleaved with tenback, 1979; Wolfe and Held, 1981; Parker, either 1.5 set blanks (for baseline measurements 1981; Magnussen and Johnsen, 1986), and it has and testing during the decay phase) or 10 set been suggested that threshold and suprareadaptation periods (for testing during the threshold aftereffects have different origins build-up phase). During adaptation the subject (Klein et al., 1974;Parker, 1981; Wolfe and scanned a horizontal fixation bar to avoid after-O'Connell, 1986). The present note reports evi-images. He was comfortably seated with his dence for a unitary mechanism.head supported by a chin-and forehead rest. In a recent experiment (Magnussen and Greenlee, 1985) we measured the growth of the threshold elevation aftereffect well beyond the saturation point during a 3 hr adapting session, and tracked its subsequent decay. We have conducted a similar experiment on the tilt aftereffect, and are now able to compare the time-courses of the complete growth and recovery from continuous adaptation routines for these two aftereffects.The tachistoscopic arrangement for measuring the tilt aftereffect has been described in several previous papers, most recently by Mag_

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confidence: 69%

Section: Afterekects Saturation Psychophysicsmentioning

confidence: 99%

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Saturation of the tilt aftereffect

Greenlee

Magnussen

1987

Vision Research

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“…The elevation in contrast threshold following adaptation has been shown to depend on the spatial frequency (Blakemore & Campbell, 1969;Pantle & Sekuler, 1968) and orientation (Blakemore & Nachmias, 1971) difference between the adapting and test gratings. The magnitude of this threshold elevation further depends on the adapting contrast (Bjiirklund & Magnussen, 1981;Blakemore & Campbell, 1969;Georgeson & Harris, 1984) and the duration of adaptation (Bjtirklund & Magnussen, 1981;Blakemore & Campbell, 1969;Magnussen & Greenlee, 1985;Rose & Evans, 1983). Although it was originally suggested that the effect of adaptation to contrast saturates after as little as 40 set (Blakemore *To whom correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

“…Although it was originally suggested that the effect of adaptation to contrast saturates after as little as 40 set (Blakemore *To whom correspondence should be addressed. & Campbell, 1969), Magnussen and Greenlee (1985) demonstrated that, for an adapting contrast of 0.6, thresholds continue to rise for up to 30-60 min of adaptation for different subjects. The time course of the dynamic range of the buildup and decay of this adaptation was found to be best fitted by a power function (i.e.…”

Section: Introductionmentioning

confidence: 99%

The time course of adaptation to spatial contrast

et al. 1991

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Abstract-We explored the buildup and decay of threshold elevation during and after adaptation to sinewave gratings in a series of experiments investigating the effects of adapting time, adapting contrast, spatial frequency and retinal eccentricity. Contrast thresholds for vertical sinewave gratings truncated in space by a one-dimensional Gaussian envelope were measured before and after adaptation to a full-field suprathreshold grating of the same spatial frequency and orientation. Thresholds were measured intermittently after adaptation in a "seen/not-seen" single presentation procedure until these thresholds returned to baseline values. The first test grating was presented 300 msec after the offset of the adapting stimulus, and thereafter at regular intervals. At different times after adaptation, contrast thresholds were estimated by off-line analysis of the data using the QUEST algorithm. Adapting time was either 1, 10, 108 or 1000 set and adapting contrast was either 9, 19, 29 or 39 dB (re. 1%). The test gratings were presented centered either at the fixation point or at 5 and 10 deg eccentricity along the horizontal meridian. The results suggest that up to the saturation level the buildup and the decay of adaptation to contrast is well described by a power function of time. The slope of the best fitting line on log-log axes is fairly constant for the adaptation times tested. As reported earlier, thresholds increased with adapting contrast and these contrast-dependent differences were evident 3OOmsec after the termination of adaptation. Adaptation at 10 deg eccentricity yielded slightly higher threshold elevations than for central vision. Based on these results, a description is given of the dynamic response of the underlying neural mechanisms.

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Modulating the global orientation bias of the visual system changes population receptive field elongations

Merkel

Hopf

Schoenfeld

2019

Human Brain Mapping

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The topographical structure of the visual system in individual subjects can be visualized using fMRI. Recently, a radial bias for the long axis of population receptive fields (pRF) has been shown using fMRI. It has been theorized that the elongation of receptive fields pointing toward the fovea results from horizontal local connections bundling orientation selective units mostly parallel to their polar position within the visual field. In order to investigate whether there is a causal relationship between orientation selectivity and pRF elongation the current study employed a global orientation adapter to modulate the orientation bias for the visual system while measuring spatial pRF characteristics. The hypothesis was that the orientation tuning change of neural populations would alter pRF elongations toward the fovea particularly at axial positions parallel and orthogonal to the affected orientation. The results indeed show a different amount of elongation of pRF units and their orientation at parallel and orthogonal axial positions relative to the adapter orientation. Within the lower left hemifield, pRF radial bias and elongation showed an increase during adaptation to a 135° grating while both parameters decreased during the presentation of a 45° adapter stimulus. The lower right visual field showed the reverse pattern. No modulation of the pRF topographies were observed in the upper visual field probably due to a vertical visual field asymmetry of sensitivity toward the low contrast spatial frequency pattern of the adapter stimulus. These data suggest a direct relationship between orientation selectivity and elongation of population units within the visual cortex.

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Marathon adaptation to spatial contrast: Saturation in sight

Cited by 58 publications

References 16 publications

Saturation of the tilt aftereffect

Saturation of the tilt aftereffect

The time course of adaptation to spatial contrast

Modulating the global orientation bias of the visual system changes population receptive field elongations

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