Upper and lower visual field differences in perceptual asymmetries

Elias, Lorin

doi:10.1016/j.brainres.2011.02.063

Cited by 72 publications

(74 citation statements)

References 158 publications

(494 reference statements)

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“…The estimated parameters of g(x, y) are listed in Table 3 and shown in Figure 7. We note that the summation field is, on average, displaced slightly to the lower left visual field, consistent with previous results showing higher contrast sensitivity for low to moderate spatial frequencies in the lower visual field (Rijsdijk et al, 1980;Thomas and Elias, 2011), and the general finding that tasks with a lower visual field advan-tage also tend to be biased to the left visual field (Christman and Niebauer, 1997;Thomas and Elias, 2011). We find that incorporating this global attenuation function to capture the falloff in sensitivity seen in our classification images also leads to an improvement in the trial-by-trial consistency of human and model responses (see below, Evaluation and comparison with competing models).…”

Section: Estimating the Local Energy Modelsupporting

confidence: 92%

Local Visual Energy Mechanisms Revealed by Detection of Global Patterns

Morgenstern

Elder

2012

J. Neurosci.

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A central goal of visual neuroscience is to relate the selectivity of individual neurons to perceptual judgments, such as detection of a visual pattern at low contrast or in noise. Since neurons in early areas of visual cortex carry information only about a local patch of the image, detection of global patterns must entail spatial pooling over many such neurons. Physiological methods provide access to local detection mechanisms at the single-neuron level but do not reveal how neural responses are combined to determine the perceptual decision. Behavioral methods provide access to perceptual judgments of a global stimulus but typically do not reveal the selectivity of the individual neurons underlying detection. Here we show how the existence of a nonlinearity in spatial pooling does allow properties of these early mechanisms to be estimated from behavioral responses to global stimuli. As an example, we consider detection of large-field sinusoidal gratings in noise. Based on human behavioral data, we estimate the length and width tuning of the local detection mechanisms and show that it is roughly consistent with the tuning of individual neurons in primary visual cortex of primate. We also show that a local energy model of pooling based on these estimated receptive fields is much more predictive of human judgments than competing models, such as probability summation. In addition to revealing underlying properties of early detection and spatial integration mechanisms in human cortex, our findings open a window on new methods for relating system-level perceptual judgments to neuron-level processing.

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Section: Estimating the Local Energy Modelsupporting

confidence: 92%

Local Visual Energy Mechanisms Revealed by Detection of Global Patterns

Morgenstern

Elder

2012

J. Neurosci.

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“…Interestingly, there is growing evidence for perceptual and neural asymmetries between the dorsal and ventral visual fields, with improved motion, global processing, and coordinate spatial judgments in the lower visual field and improved visual search, local processing, and categorical judgments in the upper visual field, especially for the left visual field (49)(50)(51)(52)(53). Such variations would not be apparent in our measurements based on eccentricity from fixation, which grouped the polar angles.…”

Section: Comparisons With Studies On the Cortical Effects Of Other Rementioning

confidence: 69%

fMRI of the rod scotoma elucidates cortical rod pathways and implications for lesion measurements

Barton

Brewer

2015

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

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Are silencing, ectopic shifts, and receptive field (RF) scaling in cortical scotoma projection zones (SPZs) the result of long-term reorganization (plasticity) or short-term adaptation? Electrophysiological studies of SPZs after retinal lesions in animal models remain controversial, because they are unable to conclusively answer this question because of limitations of the methodology. Here, we used functional MRI (fMRI) visual field mapping through population RF (pRF) modeling with moving bar stimuli under photopic and scotopic conditions to measure the effects of the rod scotoma in human early visual cortex. As a naturally occurring central scotoma, it has a large cortical representation, is free of traumatic lesion complications, is completely reversible, and has not reorganized under normal conditions (but can as seen in rod monochromats). We found that the pRFs overlapping the SPZ in V1, V2, V3, hV4, and VO-1 generally (i) reduced their blood oxygen level-dependent signal coherence and (ii) shifted their pRFs more eccentric but (iii) scaled their pRF sizes in variable ways. Thus, silencing, ectopic shifts, and pRF scaling in SPZs are not unique identifiers of cortical reorganization; rather, they can be the expected result of short-term adaptation. However, are there differences between rod and cone signals in V1, V2, V3, hV4, and VO-1? We did not find differences for all five maps in more peripheral eccentricities outside of rod scotoma influence in coherence, eccentricity representation, or pRF size. Thus, rod and cone signals seem to be processed similarly in cortex. can adult human visual cortex reorganize after the removal of visual input?" This question can be studied through the effects of retinal lesions (causing scotomas), in which input from the retina has been removed, but cortical representations of the scotoma projection zone (SPZ) remain intact. Accordingly, emphasis must be placed on teasing apart effects of scotomas that relate to short-term cortical adaptation from those of long-term cortical plasticity (1) (terminology review is in ref.2). Here, we investigate this question in human cortex by using functional MRI (fMRI) to measure the immediate cortical SPZ responses in the unique paradigm of the naturally occurring rod scotoma.The photoreceptors in humans can be divided into two classes: cones, which are primarily responsible for vision under high-luminance (photopic) conditions, and rods, which are primarily responsible for vision under low-luminance (scotopic) conditions when the cones are inactive. The cones are an order of magnitude more highly concentrated in the fovea relative to the periphery, where they inform our most detailed visual experience (3). In contrast, the greatest concentrations of rods are more than ∼10°e ccentric from fixation and become increasingly sparse toward fixation until they are completely absent. This roughly circular rodfree zone covers a radius of ∼0.6-0.8°of visual angle about the fixation point (diameter = ∼1.25-1.7°) (4, 5). Under scotopic conditions, a...

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“…When this factor is controlled, the apparent bias for the upper part of words vanishes completely, as we revealed in Experiment 2. Hence, the bias for the upper part of objects that occurs in the visual perception of particular features in faces (e.g., Caldara & Seghier, 2009) and objects (Thomas & Elias, 2011) does not seem to affect the automatic detection of letter features during visual-word recognition.…”

Section: Discussionmentioning

confidence: 98%

“…One explanation is that this bias parallels the upward biases that occur in the visual perception of features of objects and faces (see Caldara et al, 2006, andElias, 2011, for recent evidence regarding these biases). As Huey (1908) indicated, "we habitually find most meanings in the upper part of objects; we ourselves are so placed and so oriented as to bring this about" (p. 65).…”

mentioning

confidence: 90%

Is there a genuine advantage to the upper part of words during lexical access? Evidence from the Stroop task

2014

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A number of recent visual-word recognition and reading experiments have concluded that the upper part of words is more important for lexical access than is the lower part, which conforms with Huey's (1908) observation. Here, we examined whether this phenomenon may simply be due to the fact that words in Indo-European languages tend to have a higher number of confusable letters in the lower than in the upper part. We manipulated the letter ambiguity of the upper and lower parts of words in two experiments in which we asked participants to report the presentation color of the upper and lower parts of color words and noncolor words, and in a baseline condition, of strings of &s (Stroop task). In Experiment 1, the lower part of noncolor words was more ambiguous than the upper part (upward-unbalanced words), whereas in Experiment 2, the ambiguities of the two parts of the noncolor words were similar (balanced words). For the upward-unbalanced noncolor words, the magnitude of lexical interference (relative to the baseline condition) was greater for the upper than for the lower part. Critically, the differences vanished when this factor was controlled (i.e., balanced words; Exp. 2). Thus, the apparent bias in favor of the upper part of words can be parsimoniously described as an idiosyncratic feature of the words' component letters.

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Upper and lower visual field differences in perceptual asymmetries

Cited by 72 publications

References 158 publications

Local Visual Energy Mechanisms Revealed by Detection of Global Patterns

Local Visual Energy Mechanisms Revealed by Detection of Global Patterns

fMRI of the rod scotoma elucidates cortical rod pathways and implications for lesion measurements

Is there a genuine advantage to the upper part of words during lexical access? Evidence from the Stroop task

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