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Perceptual latency priming and illusory line motion: Facilitation by gradients of attention?

100%
Scharlau I., Horstmann G.
Advances in Cognitive Psychology
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2006
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vol. 2
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issue 1
87-97
EN
The phenomena of illusory line motion and perceptual latency priming are both assumed to reflect a facilitation of perceptual latency. The explanation of illusory line motion presupposes that attention is distributed in a gradient fashion whereas this is not a necessary part of the explanation of perceptual latency priming. Two experiments test whether an attentional gradient is present in perceptual latency priming. Evidence for a gradient was found within 2.5° of visual angle around the attended location, but not at a distance of 5° and more.
2
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The effects of spatial and temporal cueing on metacontrast masking

100%
Bruchmann M., Hintze P., Mota S.
Advances in Cognitive Psychology
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2011
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vol. 7
132-141
EN
We studied the effects of selective attention on metacontrast masking with 3 different cueing experiments. Experiments 1 and 2 compared central symbolic and peripheral spatial cues. For symbolic cues, we observed small attentional costs, that is, reduced visibility when the target appeared at an unexpected location, and attentional costs as well as benefits for peripheral cues. All these effects occurred exclusively at the late, ascending branch of theU-shaped metacontrast masking function, although the possibility exists that cueing effects at the early branch were obscured by a ceiling effect due to almost perfect visibility at short stimulus onset asynchronies (SOAs). In Experiment 3, we presented temporal cues that indicated when the target was likely to appear, not where. Here, we also observed cueing effects in the form of higher visibility when the target appeared at the expected point in time compared to when it appeared too early. However, these effects were not restricted to the late branch of the masking function, but enhanced visibility over the complete range of the masking function. Given these results we discuss a common effect for different types of spatial selective attention on metacontrast masking involving neural subsystems that are different from those involved in temporal attention.
3
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Electrophysiological activation by masked primes: Independence of prime-related and target-related activities

100%
Klotz W., Heumann M., Ansorge U., Neumann O.
Advances in Cognitive Psychology
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2007
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vol. 3
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issue 4
449-465
EN
Visual stimuli that are made invisible by metacontrast masking (primes) have a marked influence on behavioral and psychophysiological measures such as reaction time (RT) and the lateralized readiness potential (LRP). 4 experiments are reported that shed light on the effects that masked primes have on the LRP. Participants had a go-nogo task in which the prime was associated with 1 of 2 responses even if the target required participants to refrain from responding. To analyze the electrophysiological responses, we computed the LRP and applied an averaging method separating the activation due to the prime and the target. The results demonstrated that (a) masked primes activate responses even in a nogo situation, (b) this prime-related activation is independent of masking, (c) and is also independent of whether prime and target require the same responses (congruent condition) or different responses (incongruent condition).
4
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Spatial processing and visual backward masking

100%
Herzog M.
Advances in Cognitive Psychology
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2007
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vol. 3
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issue 1-2
85-92
EN
Most theories of visual masking focus primarily on the temporal aspects of visual information processing, strongly neglecting spatial factors. In recent years, however, we have shown that this position is not tenable. Spatial aspects cannot be neglected in metacontrast, pattern and un-masking. Here, we review these results.
5
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An analysis of visual masking, with a defense of 'Stopped Processing'

100%
Reeves A.
Advances in Cognitive Psychology
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2007
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vol. 3
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issue 1-2
57-65
EN
The use of a backward mask (a patterned mask which follows the target in time) to 'stop the processing' of the target illustrates an important application of masking - the study of the 'microgenesis' of visual perception, that is, visual processing over about the first one-fifth of a second. This paper provides evidence for stopped processing and some applications of this to object recognition and letter detection. The paper also discusses the notion of an 'active filter' which may help to account for Type-A masking but at best can only account for Type-B masking in part. I conclude that masking, while illuminating various areas of vision science, is under-utilized, perhaps because the theoretical justification for such masking is still uncertain, and perhaps because of the care needed to establish that the mask does indeed 'stop' processing.
6
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Temporal processes in prime–mask interaction: Assessing perceptual consequences of masked information

75%
Scharlau I.
Advances in Cognitive Psychology
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2007
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vol. 3
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issue 1-2
241-255
EN
Visual backward masking is frequently used to study the temporal dynamics of visual perception. These dynamics may include the temporal features of conscious percepts, as suggested, for instance, by the asynchronous-updating model (Neumann, 1982) and perceptual-re-touch theory (Bachmann, 1994). These models predict that the perceptual latency of a visual backward mask is shorter than that of a like reference stimulus that was not preceded by a masked stimulus. The prediction has been confirmed by studies using temporal-order judgments: For certain asynchronies between mask and reference stimulus, temporal-order reversals are quite frequent (e.g. Scharlau, & Neumann, 2003a). However, it may be argued that these reversals were due to a response bias in favour of the mask rather than true temporal-perceptual effects. I introduce two measures for assessing latency effects that (1) are not prone to such a response bias, (2) allow to quantify the latency gain, and (3) extend the perceptual evidence from order reversals to duration/interval perception, that is, demonstrate that the perceived interval between a mask and a reference stimulus may be shortened as well as prolonged by the presence of a masked stimulus. Consequences for theories of visual masking such as asynchronous-updating, perceptual-retouch, and reentrant models are discussed.
7
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Metacontrast masking and the cortical representation of surface color: dynamical aspects of edge integration and contrast gain control

63%
Rudd M.
Advances in Cognitive Psychology
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2007
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vol. 3
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issue 1-2
327-347
EN
This paper reviews recent theoretical and experimental work supporting the idea that brightness is computed in a series of neural stages involving edge integration and contrast gain control. It is proposed here that metacontrast and paracontrast masking occur as byproducts of the dynamical properties of these neural mechanisms. The brightness computation model assumes, more specifically, that early visual neurons in the retina, and cortical areas V1 and V2, encode local edge signals whose magnitudes are proportional to the logarithms of the luminance ratios at luminance edges within the retinal image. These local edge signals give rise to secondary neural lightness and darkness spatial induction signals, which are summed at a later stage of cortical processing to produce a neural representation of surface color, or achromatic color, in the case of the chromatically neutral stimuli considered here. Prior to the spatial summation of these edge-based induction signals, the weights assigned to local edge contrast are adjusted by cortical gain mechanisms involving both lateral interactions between neural edge detectors and top-down attentional control. We have previously constructed and computer-simulated a neural model of achromatic color perception based on these principles and have shown that our model gives a good quantitative account of the results of several brightness matching experiments. Adding to this model the realistic dynamical assumptions that 1) the neurons that encode local contrast exhibit transient firing rate enhancement at the onset of an edge, and 2) that the effects of contrast gain control take time to spread between edges, results in a dynamic model of brightness computation that predicts the existence Broca-Sulzer transient brightness enhancement of the target, Type Bmetacontrast masking, and a form of paracontrast masking in which the target brightness is enhanced when the mask precedes the target in time.
8
Content available remote

Common-onset masking simulated with a distributed-code model

63%
Bridgeman B.
Advances in Cognitive Psychology
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2007
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vol. 3
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issue 1-2
33-40
EN
A distributed-coding model incorporating lateral inhibition in a simulated nerve network has been successful in accounting for many properties of backward masking (Bridgeman, 1971, 1978), linking modeling with neurophysiology and psychophysics. Metacontrast is a variety of backward masking that is of particular interest in uncovering properties of visual coding because target and mask do not overlap in time or space, and it is the first stimulus that is reduced in visibility, not the second. The lateral inhibitory model can also simulate common-onset masking, where a target and mask appear simultaneously but the mask disappears after a variable delay, and it can reproduce qualitatively the effects of attention on object substitution by varying the time interval over which sensory codes are analyzed.
9
Content available remote

The role of feedback in visual masking and visual processing

51%
Macknik S., Martinez-Conde S.
Advances in Cognitive Psychology
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2007
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vol. 3
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issue 1-2
125-152
EN
This paper reviews the potential role of feedback in visual masking, for and against. Our analysis reveals constraints for feedback mechanisms that limit their potential role in visual masking, and in all other general brain functions. We propose a feedforward model of visual masking and provide a hypothesis to explain the role of feedback in visual masking and visual processing in general. We review the anatomy and physiology of feedback mechanisms, and propose that the massive ratio of feedback versus feedforward connections in the visual system may be explained solely by the critical need for top-down attentional modulation. We discuss the merits of visual masking as a tool to discover the neural correlates of consciousness, especially as compared to other popular illusions, such as binocular rivalry. Finally, we propose a new set of neurophysiological standards needed to establish whether any given neuron or brain circuit may be the neural substrate of awareness.
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