Low-level Visual Processing Research Articles

Fear improves mental rotation of low-spatial-frequency visual representation.

Previous studies have demonstrated that the brief presentation of a fearful face improves not only low-level visual processing such as contrast and orientation sensitivity but also improves visuospatial processing. In the present study, we investigated whether fear improves mental rotation efficiency (i.e., the mental rotation rate) because of the effect of fear on the sensitivity of magnocellular neurons. We asked 2 groups of participants to perform a mental rotation task with either low-pass or high-pass filtered 3-dimensional objects. Following the presentation of a fearful face, participants mentally rotated objects faster compared with when a neutral face was presented but only for low-pass filtered objects. The results suggest that fear improves mental rotation efficiency by increasing sensitivity to motion-related visual information within the magnocellular pathway.

P1-9: Relationship between Color Shifts in Land's Two-Color Method and Higher- and Lower-Level Visual Information

Land's two-color method gives rise to apparent full-color perception, even though only two colors (e.g., red and gray) are used. Previous studies indicate that chromatic adaptation, color memory, and inductive effects contribute to the shifts of color perception from real to illusory colors (e.g., Kuriki, 2006 Vision Research46 3055–3066). This paper investigates the relationship between the color shifts induced by Land images and the skewness of the luminance histogram. In Experiment 1, several Land images are created based on a yellow ball, and the magnitude of the color shifts of the images are measured. The results of Experiment 1 show a significant correlation between the magnitude of the color shifts and skewness, suggesting that skewness is critical for the color shifts. In Experiment 2, we test the hypothesis that color shifts depends on just skewness; the color shifts should be invariant even if the Land images are scrambled. However, the results of Experiment 2 demonstrate that scrambled Land images exhibit less intense color shifts, suggesting that color shifts are determined by the object's overall shape or surface gloss, not just skewness. Taken together, we conclude that both low-level visual processes, such as those associated with luminance histogram skew, and high-level cognitive functions, such as object interpretation or understanding of surface gloss, are involved in the color shift of Land images.

Studying face processing in autism through the interplay between high and low level visual processes

Studying face processing in autism through the interplay between high and low level visual processes

Abnormal Brain Activation in Neurofibromatosis Type 1: A Link between Visual Processing and the Default Mode Network

Neurofibromatosis type 1 (NF1) is one of the most common single gene disorders affecting the human nervous system with a high incidence of cognitive deficits, particularly visuospatial. Nevertheless, neurophysiological alterations in low-level visual processing that could be relevant to explain the cognitive phenotype are poorly understood. Here we used functional magnetic resonance imaging (fMRI) to study early cortical visual pathways in children and adults with NF1. We employed two distinct stimulus types differing in contrast and spatial and temporal frequencies to evoke relatively different activation of the magnocellular (M) and parvocellular (P) pathways. Hemodynamic responses were investigated in retinotopically-defined regions V1, V2 and V3 and then over the acquired cortical volume. Relative to matched control subjects, patients with NF1 showed deficient activation of the low-level visual cortex to both stimulus types. Importantly, this finding was observed for children and adults with NF1, indicating that low-level visual processing deficits do not ameliorate with age. Moreover, only during M-biased stimulation patients with NF1 failed to deactivate or even activated anterior and posterior midline regions of the default mode network. The observation that the magnocellular visual pathway is impaired in NF1 in early visual processing and is specifically associated with a deficient deactivation of the default mode network may provide a neural explanation for high-order cognitive deficits present in NF1, particularly visuospatial and attentional. A link between magnocellular and default mode network processing may generalize to neuropsychiatric disorders where such deficits have been separately identified.

Skilled Deaf Readers Have an Enhanced Perceptual Span in Reading

Recent evidence suggests that, compared with hearing people, deaf people have enhanced visual attention to simple stimuli viewed in the parafovea and periphery. Although a large part of reading involves processing the fixated words in foveal vision, readers also utilize information in parafoveal vision to preprocess upcoming words and decide where to look next. In the study reported here, we investigated whether auditory deprivation affects low-level visual processing during reading by comparing the perceptual span of deaf signers who were skilled and less-skilled readers with the perceptual span of skilled hearing readers. Compared with hearing readers, the two groups of deaf readers had a larger perceptual span than would be expected given their reading ability. These results provide the first evidence that deaf readers’ enhanced attentional allocation to the parafovea is used during complex cognitive tasks, such as reading.

Learned Predictiveness Speeds Visual Processing

When humans learn that the presence of a cue predicts the likelihood of an outcome, they can exploit this learned predictiveness, such that formation of subsequent associations between that cue and new outcomes is facilitated. Could such enhanced selection for association arise early enough to facilitate low-level visual processing? In a test of this possibility, adult volunteers first engaged in a value-learning task involving faces that were differentially predictive of monetary wins or losses. Later, in a simple recognition task, these faces were briefly presented for a variable duration and then masked. The critical presentation duration needed to produce criterion-level recognition was measured to index the visual processing speed for each learned face. Critical duration was significantly shorter for stimuli with high learned predictiveness than for stimuli with low learned predictiveness, regardless of whether they were associated with wins or losses. These results show that neural mechanisms involved in predicting future outcomes are able to modulate visual processing efficiency, probably via cortical feedback processes.

Residual effects of ecstasy (3,4‐methylenedioxymethamphetamine) on low level visual processes

'Ecstasy' (3,4-methylenedioxymethamphetamine) induces impaired functioning in the serotonergic system, including the occipital lobe. This study employed the 'tilt aftereffect' paradigm to operationalise the function of orientation-selective neurons among ecstasy consumers and controls as a means of investigating the role of reduced serotonin on visual orientation processing. The magnitude of the tilt aftereffect reflects the extent of lateral inhibition between orientation-selective neurons and is elicited to both 'real' contours, processed in visual cortex area V1, and illusory contours, processed in V2. The magnitude of tilt aftereffect to both contour types was examined among 19 ecstasy users (6 ecstasy only; 13 ecstasy-plus-cannabis users) and 23 matched controls (9 cannabis-only users; 14 drug-naive). Ecstasy users had a significantly greater tilt magnitude than non-users for real contours (Hedge's g = 0.63) but not for illusory contours (g = 0.20). These findings provide support for literature suggesting that residual effects of ecstasy (and reduced serotonin) impairs lateral inhibition between orientation-selective neurons in V1, which however suggests that ecstasy may not substantially affect this process in V2. Multiple studies have now demonstrated ecstasy-related deficits on basic visual functions, including orientation and motion processing. Such low-level effects may contribute to the impact of ecstasy use on neuropsychological tests of visuospatial function.

Abnormal Achromatic and Chromatic Contrast Sensitivity in Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is a monogenic disorder with the majority of patients presenting subtle to moderate cognitive impairments. Visuospatial deficits are considered to be one of the hallmark characteristics of their cognitive profile. However, low-level visual processing has not been previously investigated. Our aim was to study contrast perception in these patients to assess the function of early visual areas. Contrast sensitivity was tested in 19 children and adolescents with NF1 and 33 control children and adolescents and 12 adults with NF1 and 24 control adults. The tasks used probed two achromatic spatiotemporal frequency channels and chromatic red-green and blue-yellow pathways. Individuals with NF1 showed significant contrast sensitivity deficits for the achromatic higher spatial frequency channel [F(₁,₈₃) = 36.1, P < 0.001] and for the achromatic low spatial high temporal (magnocellular) frequency channel [F(₁,₇₂) = 8.0, P < 0.01]. Furthermore, individuals with NF1 presented a significant deficit in chromatic red-green (parvocellular) contrast sensitivity (P < 0.01) but not in blue-yellow (koniocelular) sensitivity. The decrease in achromatic sensitivity for higher spatial frequency was observed throughout the visual field, in both central and peripheral locations. In contrast, central contrast sensitivity for the magnocellular-biased condition was relatively preserved and only peripheral sensitivity was affected. Interestingly, the same pattern of deficits was found in both age groups tested. These findings showed that contrast sensitivity is impaired in patients with NF1, associating for the first time abnormal low-level vision to the cognitive profile of this disorder.

The influence of cognitive load on visual perceptual processing

Event Abstract Back to Event The influence of cognitive load on visual perceptual processing Ping Liu1*, Luca Cocchi2, Jason Forte1, David K. Sewell1 and Olivia Carter1 1 The University of Melbourne, School of Psychological Science, Australia 2 University of Queensland, Queensland Brain Institute, Australia Contrary to the majority of dual-task studies, recent studies show that when observers were holding information in working memory, performance on an unrelated visual perceptual task (e.g., grouping-by-proximity) was improved (increased accuracy & reduced reaction time)(Cocchi et al., 2011). These results suggest cognitive control mechanisms supporting working memory may facilitate concurrent but independent visual perceptual processing. To further explore the nature of perceptual facilitation as a function of cognitive load, two studies were run exploring whether cognitive load could influence sensitivity to low-contrast stimuli or modulate surround suppression mechanisms in low-level visual processing. A contrast detection task was employed in the first study, where participants were asked to judge the orientation (horizontal vs. vertical) of a small Gabor of various contrasts presented at one of the four corners of an imaginary square. A visual motion discrimination task eliciting surround-suppression was used in the second study, where participants were asked to judge the motion direction (left vs. right) of a large high-contrast drifting Gabor of various exposure durations presented at fovea. In both studies, the perceptual tasks were conducted during a concurrent no-, low- and high-working memory load task. Preliminary results of the first experiment showed no difference in the contrast thresholds for the detection task across conditions, suggesting that cognitive load does not enhance low-level visual perceptual processing. With data analysis for the second study ongoing, a reduction or increase in exposure thresholds for the motion task under working memory loads would suggest cognitive load either reduces or increases visual surround-suppression respectively. References Cocchi, L., Toepel, U., De Lucia, M., Martuzzi, R., Wood, S. J., Carter, O., and Murray, M. (2011). Working memory load improves early stages of independent visual processing. Neuropsychologia 49, 92-102. Keywords: dual-task performance, cognitive control, top-down modulation, working memory, Visual Perception Conference: ACNS-2012 Australasian Cognitive Neuroscience Conference, Brisbane, Australia, 29 Nov - 2 Dec, 2012. Presentation Type: Poster Presentation Topic: Sensation and Perception Citation: Liu P, Cocchi L, Forte J, Sewell DK and Carter O (2012). The influence of cognitive load on visual perceptual processing. Conference Abstract: ACNS-2012 Australasian Cognitive Neuroscience Conference. doi: 10.3389/conf.fnhum.2012.208.00079 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 25 Oct 2012; Published Online: 07 Nov 2012. * Correspondence: Miss. Ping Liu, The University of Melbourne, School of Psychological Science, Melbourne, Australia, virliu@unimelb.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Ping Liu Luca Cocchi Jason Forte David K Sewell Olivia Carter Google Ping Liu Luca Cocchi Jason Forte David K Sewell Olivia Carter Google Scholar Ping Liu Luca Cocchi Jason Forte David K Sewell Olivia Carter PubMed Ping Liu Luca Cocchi Jason Forte David K Sewell Olivia Carter Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

A neurobehavioral model of flexible spatial language behaviors.

We propose a neural dynamic model that specifies how low-level visual processes can be integrated with higher level cognition to achieve flexible spatial language behaviors. This model uses real-word visual input that is linked to relational spatial descriptions through a neural mechanism for reference frame transformations. We demonstrate that the system can extract spatial relations from visual scenes, select items based on relational spatial descriptions, and perform reference object selection in a single unified architecture. We further show that the performance of the system is consistent with behavioral data in humans by simulating results from 2 independent empirical studies, 1 spatial term rating task and 1 study of reference object selection behavior. The architecture we present thereby achieves a high degree of task flexibility under realistic stimulus conditions. At the same time, it also provides a detailed neural grounding for complex behavioral and cognitive processes.

Object Recognition Can Be Viewpoint Dependent or Invariant – It's Just a Matter of Time and Task

As we move through our environment, we encounter familiar objects from various viewpoints. Despite the ensuing variability of the images projected onto the retina, we have seemingly little difficulty when it comes to recognizing objects we encounter. We can, however, see how the objects are oriented, suggesting that object recognition is to a certain degree dissociable from perception of other object “features” such as orientation. Changes in orientation of objects, particularly inversion, can also affect how we perceive the objects. A particularly illustrative example (shown in Figure ​Figure1)1) is that of the Thatcher illusion (Thompson, 1980), where the grotesque appearance of a face with its inverted eyes and mouth is “hidden” when the whole face is also inverted. The percept itself, therefore, is affected by the change in orientation. In addition, there are also subtle effects of viewpoint changes on object recognition itself. For example, identifying rotated objects is more difficult when they are briefly presented than when viewing time is unlimited (Lawson and Jolicoeur, 2003), and identifying a face is considerably more difficult the face has been inverted (Yin, 1969), as is discrimination between characters “b” and “d,” or “p” and “q” which requires (physical or mental) rotation of the characters to upright, before we can be certain which letter we are looking at (Corballis and McLaren, 1984). Figure 1 Unaltered and “thatcherized” version of Margaret Thatcher's face. The grotesque appearance of the face when its eyes and mouth are inverted is hidden by the inversion of the whole image. Rotating the pictures to upright makes discrimination ... These subtle, yet persistent, effects of viewpoint changes on perception and recognition arise as a consequence of how visual object processing is handled by the brain. Here, I discuss how neural mechanisms underlying visual processing give rise to perception and recognition which can be both viewpoint dependent and viewpoint invariant depending on the timing of those processes, as well as specific task demands or current “perceptual goals” of an individual. To do so, I will firstly explain how temporal dynamics of low-level visual processing may give rise to impaired recognition at short viewing latencies and suggest that this may also relate to effects of viewpoint changes on perceptual experience. I will then discuss how the perceptual goals of an individual determines whether recognition is accomplished in viewpoint invariant or dependent manner with a particular focus on cognitive operations thought to be subserved by ventral and dorsal visual streams, namely object recognition and mental rotation, respectively.

Necker cube: Stimulus-related (low-level) and percept-related (high-level) EEG signatures early in occipital cortex

During observation of an ambiguous Necker cube, our percept changes spontaneously although the external stimulus does not. An EEG paradigm allowing time-resolved EEG measurement during endogenous perceptual reversals recently revealed a chain of ERP correlates beginning with an early occipital positivity at around 130 ms (Reversal Positivity, "RP"). In order to better understand the functional role of this RP, we investigated its relation to the P100, which is spatiotemporally close, typically occurring 100 ms after onset of a visual stimulus at occipital electrodes. We compared the relation of the ERP amplitudes to varying sizes of ambiguous Necker cubes. The main results are: (1) The P100 amplitude increases monotonically with stimulus size but is independent of the participants' percept. (2) The RP, in contrast, is percept-related and largely unaffected by stimulus size. (3) A similar pattern to RP was found for reaction times: They depend on the percept but not on stimulus size. We speculate that the P100 reflects processing of elementary visual features, while the RP is related to a processing conflict during 3D interpretation that precedes a reversal. The present results indicate that low-level visual processing (related to stimulus size) and (relative) high-level processing (related to perceptual reversal) occur in close spatial and temporal vicinity.

No evidence for a fundamental visual motion processing deficit in adolescents with autism spectrum disorders

It has been suggested that atypicalities in low-level visual processing contribute to the expression and development of the unusual cognitive and behavioral profile seen in autism spectrum disorders (ASD). However, previous investigations have yielded mixed results. In the largest study of its kind (ASD n = 89; non-ASD = 52; mean age 15 years 6 months) and testing across the spectrum of IQ (range 52-133), we investigated performance on three measures of basic visual processing: motion coherence, form-from-motion and biological motion (BM). At the group level, we found no evidence of differences between the two groups on any of the tasks, suggesting that there is no fundamental visual motion processing deficit in individuals with an ASD, at least by adolescence. However, we identified a tail of individuals with ASD (18% of the sample) who had exceptionally poor BM processing abilities compared to the non-ASD group, and who were characterized by low IQ. For the entire sample of those both with and without ASD, performance on the BM task uniquely correlated with performance on the Frith-Happé animations, a higher-level task that demands the interpretation of moving, interacting agents in order to understand mental states. We hypothesize that this association reflects the shared social-cognitive characteristics of the two tasks, which have a common neural underpinning in the superior temporal sulcus.

Excitatory repetitive transcranial magnetic stimulation over the dorsolateral prefrontal cortex does not affect perceptual filling-in in healthy volunteers

Collinear flankers increase the reports of the target present, an effect attributed to excitatory activation induced by the flankers on the target location, which consequently induces the filling-in effect ( Polat & Sagi, 2007). Repetitive transcranial magnetic stimulation (rTMS) is a powerful tool for non-invasive investigation of neural processing in the human brain. We explored how rTMS over the left dorsolateral prefrontal cortex (LDLPFC) affects filling-in perception in normal controls. Active and Sham rTMS were used over the DLPFC (90% of the subjects’ motor threshold (MT)) using 10-Hz pulses for 5- and 20-s intertrain intervals. We used the filling-in paradigm to probe hit rates (pHit) and false-positive reports (false alarm, pFA). We found that the changes in the filling-in effect (pHit, pFA) were not significantly different between the groups. However, the reaction time (RT) was significantly reduced in the rTMS group but not in the Sham group. Our results suggest that neural processing in this area is not critical in the processing of the filling-in effect, probably because this process is mediated by lower-level visual processing.

Similar neural adaptation mechanisms underlying face gender and tilt aftereffects

Visual aftereffects have been found for a wide variety of stimuli, ranging from oriented lines to human faces, but previous results suggested that face aftereffects were qualitatively different from orientation (tilt) aftereffects. Using computational models, we predicted that these differences were due to the limited range of faces used in previous studies. Here we report psychophysical results verifying this prediction. We used the same paradigm to test tilt aftereffects (TAE) and face gender aftereffects (FAE) and found that they exhibited qualitatively similar aftereffect curves, when a sufficiently large range of test faces was used. Overall, the results suggest that similar adaptation mechanisms may underlie both high-level and low-level visual processing.

Emotion and perception: the role of affective information

Visual perception and emotion are traditionally considered separate domains of study. In this article, however, we review research showing them to be less separable than usually assumed. In fact, emotions routinely affect how and what we see. Fear, for example, can affect low-level visual processes, sad moods can alter susceptibility to visual illusions, and goal-directed desires can change the apparent size of goal-relevant objects. In addition, the layout of the physical environment, including the apparent steepness of a hill and the distance to the ground from a balcony can both be affected by emotional states. We propose that emotions provide embodied information about the costs and benefits of anticipated action, information that can be used automatically and immediately, circumventing the need for cogitating on the possible consequences of potential actions. Emotions thus provide a strong motivating influence on how the environment is perceived. WIREs Cogni Sci 2011 2 676-685 DOI: 10.1002/wcs.147 This article is categorized under: Psychology > Emotion and Motivation.

Pupil size changes during recognition memory

Pupils dilate to a greater extent when participants view old compared to new items during recognition memory tests. We report three experiments investigating the cognitive processes associated with this pupil old/new effect. Using a remember/know procedure, we found that the effect occurred for old items that were both remembered and known at recognition, although it was attenuated for known compared to remembered items. In Experiment 2, the pupil old/new effect was observed when items were presented acoustically, suggesting the effect does not depend on low-level visual processes. The pupil old/new effect was also greater for items encoded under deep compared to shallow orienting instructions, suggesting it may reflect the strength of the underlying memory trace. Finally, the pupil old/new effect was also found when participants falsely recognized items as being old. We propose that pupils respond to a strength-of-memory signal and suggest that pupillometry provides a useful technique for exploring the underlying mechanisms of recognition memory.

Is it a he or a she? Behavioral and computational approaches to sex categorization

Can people categorize the sex of neonate faces? Our experiment tested the sex categorization of neonate faces by adult participants. We used a set of 120 Caucasian faces (adults and 4-day-old neonates) that were presented just once to a large sample of participants. A computational model of low-level visual processing, based on Gabor filters, was used to explore the relation between spatial-frequency information and sex categorization. The results showed that participants were able to categorize the sex of the faces, but were less accurate with neonate (d' = 0.36, β = -.97) than with adult (d' = 3.02, β = -.93) faces. Moreover, faces were more frequently categorized as boys' than girls' faces. The computational model suggests that specific spatial-frequency channels carry most of the useful information for the categorization task. Overall, the findings reveal that subtle differences in neonate facial structure were enough to allow the sex categorization of neonate faces, although accuracy was low in both adults and the computational model of low-level visual processing.

Humans and monkeys share visual representations

Conceptual abilities in animals have been shown at several levels of abstraction, but it is unclear whether the analogy with humans results from convergent evolution or from shared brain mechanisms inherited from a common origin. Macaque monkeys can access "non-similarity-based concepts," such as when sorting pictures containing a superordinate target category (animal, tree, etc.) among other scenes. However, such performances could result from low-level visual processing based on learned regularities of the photographs, such as for scene categorization by artificial systems. By using pictures of man-made objects or animals embedded in man-made or natural contexts, the present study clearly establishes that macaque monkeys based their categorical decision on the presence of the animal targets regardless of the scene backgrounds. However, as is found with humans, monkeys performed better with categorically congruent object/context associations, especially when small object sizes favored background information. The accuracy improvements and the response-speed gains attributable to superordinate category congruency in monkeys were strikingly similar to those of human subjects tested with the same task and stimuli. These results suggest analogous processing of visual information during the activation of abstract representations in both humans and monkeys; they imply a large overlap between superordinate visual representations in humans and macaques as well as the implicit use of experienced associations between object and context.

Fast saccades toward numbers: Simple number comparisons can be made in as little as 230 ms

Visual psychophysicists have recently developed tools to measure the maximal speed at which the brain can accurately carry out different types of computations (H. Kirchner & S. J. Thorpe, 2006). We use this methodology to measure the maximal speed with which individuals can make magnitude comparisons between two single-digit numbers. We find that individuals make such comparisons with high accuracy in 306 ms on average and are able to perform above chance in as little as 230 ms. We also find that maximal speeds are similar for "larger than" and "smaller than" number comparisons and in a control task that simply requires subjects to identify the number in a number-letter pair. The results suggest that the brain contains dedicated processes involved in implementing basic number comparisons that can be deployed in parallel with processes involved in low-level visual processing.