Measurements of chromatic and achromatic afterimages

Kelly, D. H.; Martinez-Uriegas, Eugenio

doi:10.1364/josaa.10.000029

Cited by 51 publications

(78 citation statements)

References 10 publications

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“…Thus, the retinal model output after the adapting grating was turned off is the same as would have been produced by visual presentation of a reversed, lower contrast grating. Generation of this negative afterimage by the model followed an exponential time course with a time constant of 3.0 s, and its decay follows a like time course, in agreement with the literature (Burbeck, 1986;Kelly & Martinez-Uriegas, 1993) and eqn. (6) above.…”

Section: Negative Afterimagessupporting

confidence: 89%

“…The model produces this spatial-frequency doubling by temporal averaging of the spatial distortions evident in the top panel of Fig. 20. 1990), changes in spatial and temporal CSFs with mean luminance (Kelly, 1971(Kelly, , 1972, the Westheimer (1967) effect, and negative afterimage formation (Virsu & Laurinen, 1977;Burbeck, 1986;Kelly & Martinez-Uriegas, 1993). Physiological predictions of model ganglion cell responses have been compared with single-cell recordings to show that the spatial and temporal tuning of the model cells is consistent with reported data.…”

Section: Discussionmentioning

confidence: 77%

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A neural model of foveal light adaptation and afterimage formation

Wilson

1997

Vis Neurosci

141

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Psychophysical research has documented the existence of three processes in light adaptation: a fast subtractive process, a divisive process that is fast at light onset and slower at light offset, and a very slow subtractive process (Hayhoe et al., 1987). In the neural model developed here, the fast subtractive process is identified with horizontal cell feedback onto cones and the divisive process with amacrine cell feedback onto bipolar cells. The very slow subtractive process is identified with the modulatory feedback circuit from amacrines via interplexiform cells to horizontal cells. A nonlinear dynamical model is developed incorporating these aspects of retinal circuitry along with both ON-and OFF-center M and P pathways. This model is shown to account for many aspects of foveal light adaptation, including negative afterimage formation, and to explain a number of the physiological differences between M and P ganglion cells, including their differing contrast-response functions.

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Section: Negative Afterimagessupporting

confidence: 89%

Section: Discussionmentioning

confidence: 77%

A neural model of foveal light adaptation and afterimage formation

Wilson

1997

Vis Neurosci

141

View full text Add to dashboard Cite

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“…The model also predicts that the signal level in the luminance channel that is based on summation of L-and M-signals remains unaffected during the modulation. This explains the absence of perceived achromatic afterimages when adapting to isoluminant stimuli (27 cone signals (L Ϫ M), as shown in Fig. 3C.…”

Section: Resultsmentioning

confidence: 67%

The unseen color aftereffect of an unseen stimulus: Insight from blindsight into mechanisms of color afterimages

Barbur

Weiskrantz

Harlow

1999

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

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We show here that, in the absence of a direct geniculostriate input in human subjects, causing loss of sight in the visual half-field contralateral to the damage, the pupil responds selectively to chromatic modulation toward the long-wavelength (red) region of the spectrum locus even when the stimulus is isoluminant for both rods and cones and entirely restricted to the subjects' ''blind'' hemifields. We also show that other colors are less or wholly ineffective. Nevertheless, red afterimages, generated by chromatic modulation toward the green region of the spectrum locus, also cause constrictions of the pupil even when green stimuli are themselves completely ineffective in the blind hemifield. Moreover, human subjects with damage to or loss of V1 are typically completely unaware of the stimulus that generates the aftereffect or of the aftereffect itself, both of which can be seen clearly in normal vision. The results show that pupillary responses can reveal the processing of color afterimages in the absence of primary visual cortex and in the absence of acknowledged awareness. This phenomenon is therefore a striking example of ''blindsight'' and makes possible the formulation of a model that predicts well the observed properties of color afterimages.

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“…By itself, this predicts a stronger afterimage in high-attention condition. We furthermore assume that the afterimage decays with a time constant of several seconds (25,64), and that increased levels of selective attention reduce this time constant. This means that a neuron that has been modulated by increased levels of attention will return quicker from an adapted state to baseline (i.e., reduced time constants) than a neuron not modulated by attention.…”

Section: Discussionmentioning

confidence: 99%

Opposing effects of attention and consciousness on afterimages

Boxtel¹,

Tsuchiya

Koch

2010

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

123

131

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The brain's ability to handle sensory information is influenced by both selective attention and consciousness. There is no consensus on the exact relationship between these two processes and whether they are distinct. So far, no experiment has simultaneously manipulated both. We carried out a full factorial 2 × 2 study of the simultaneous influences of attention and consciousness (as assayed by visibility) on perception, correcting for possible concurrent changes in attention and consciousness. We investigated the duration of afterimages for all four combinations of high versus low attention and visible versus invisible. We show that selective attention and visual consciousness have opposite effects: paying attention to the grating decreases the duration of its afterimage, whereas consciously seeing the grating increases the afterimage duration. These findings provide clear evidence for distinctive influences of selective attention and consciousness on visual perception.ince the latter part of the past century, interest in the influences of selective attention and consciousness on perception has steadily increased. This discussion has raised the question of the relationship between attention and consciousness. By attention, we refer to selective perceptual attention and not vigilance or arousal; by consciousness, we refer to the content of consciousness (sometimes also referred to as awareness), and not to states of consciousness (e.g., wakefulness, dreamless sleep, or coma). Though some claim that both processes are inextricably connected (1-4), others suggest a certain level of independence (5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Psychophysical studies show that observers can pay attention to an invisible stimulus (15,16), and that a stimulus can be clearly seen in the (near) absence of attention (4,17). Though these data could be explained by arguing that these two processes covary and therefore any increase (respectively decrease) in one is associated with a similar but smaller increase (respectively decrease) in the other, this argument fails if attention and consciousness were to have opposing perceptual effects on the same stimulus. Finding such opponency would considerably strengthen the hypothesis that these processes are distinct (5).Afterimage duration is a well-suited measure for the study of attention and consciousness. Changes in afterimage durations reflect the attentional and visibility manipulations during the afterimage induction phase. This permits the temporal separation of the attentional/visibility manipulations on the afterimage inducer and their subjective monitoring, and the measurement of the resultant effects (e.g., on afterimage appearance). This procedure effectively obviates the need for a simultaneous dual-task procedure.Many afterimage and aftereffect studies are devoted to the influences of attention or consciousness in isolation. For example, removing stimuli from conscious content via various masking techniques that manipulate visibility decreases the motion aftereffect durations ...

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Measurements of chromatic and achromatic afterimages

Cited by 51 publications

References 10 publications

A neural model of foveal light adaptation and afterimage formation

A neural model of foveal light adaptation and afterimage formation

The unseen color aftereffect of an unseen stimulus: Insight from blindsight into mechanisms of color afterimages

Opposing effects of attention and consciousness on afterimages

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