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•The extrastriate cortex responds to visual symmetry. The extrastriate symmetry activation generates and event related potential (ERP) called the sustained posterior negativity (SPN).•The SPN indicates how the brain processes visual symmetry and constructs extraretinal representations. Some stimulus types may representations even during secondary tasks, contrary to previous beliefs.•Dot patterns and polygons were compared, revealing differences in how the brain represents symmetry.•Polygons reduced the perspective cost compared to dot patterns, affecting extraretinal representation.•Achieving view invariance is more complex than suggested, as perspective cost was not reduced to zero in any case. Symmetrical objects only project a symmetrical image onto the retina when viewed from certain angles. Previous work has investigated the ERP response to visual symmetry in frontoparallel and perspective views. When participants are attending to regularity, the ERPs are the same. When participants are attending to colour, the response to perspective symmetry is reduced. We term this reduction ‘perspective cost’. We predicted that perspective cost would be lessened if the stimuli were polygons rather than dot patterns. This prediction was confirmed in a new experiment. This result suggests some stimuli may support automatic 3D interpretation better than others. However, the facilitatory effect of polygons was relatively small, and perspective cost was not eliminated. Furthermore, this study also revealed that attention to symmetry is not always sufficient to eliminate perspective cost.

When a photograph of the back of a hand with the fingers extended to the depth is observed upside-down, the hand appears vertically squashed, with extremely short fingers. The first aim of this study was to quantitatively measure the “frog hand illusion (FHI)”, named after its bizarre appearance, and the second aim was to examine whether the dominant hand affects the strength of FHI. We measured the apparent shortening of the fingers using the method of constant stimuli. The results showed that the fingers of the inverted hand appeared to be shorter than those of the upright hand by about 5% on average. No effect of the dominant hand was observed. We propose the hypothesis that FHI occurs because of the attenuation of perceptual constancy, which might stem from observing the hand image from an atypical viewpoint.

Rodents rely on their whiskers as vital sensory tools for tactile perception, enabling them to distinguish textures and shapes. Ensuring the reliability and constancy of tactile perception under varying stimulus conditions remains a fascinating and fundamental inquiry. This study explores the impact of stimulus configurations, including whisker movement velocity and object spatial proximity, on texture discrimination and stability in rats. To address this issue, we employed three distinct approaches for our investigation. Stimulus configurations notably affected tactile inputs, altering whisker vibration’s kinetic and kinematic aspects with consistent effects across various textures. Through a texture discrimination task, rats exhibited consistent discrimination performance irrespective of changes in stimulus configuration. However, alterations in stimulus configuration significantly affected the rats’ ability to maintain stability in texture perception. Additionally, we investigated the influence of stimulus configurations on cortical neuronal responses by manipulating them experimentally. Notably, cortical neurons demonstrated substantial and intricate changes in firing rates without compromising the ability to discriminate between textures. Nevertheless, these changes resulted in a reduction in texture neuronal response stability. Stimulating multiple whiskers led to improved neuronal texture discrimination and maintained coding stability. These findings emphasize the importance of considering numerous factors and their interactions when studying the impact of stimulus configuration on neuronal responses and behavior.

In everyday acoustic environments, reverberation alters the speech signal received at the ears. Normal-hearing listeners are robust to these distortions, quickly recalibrating to achieve accurate speech perception. Over the past two decades, multiple studies have investigated the various adaptation mechanisms that listeners use to mitigate the negative impacts of reverberation and improve speech intelligibility. Following the PRISMA guidelines, we performed a systematic review of these studies, with the aim to summarize existing research, identify open questions, and propose future directions. Two researchers independently assessed a total of 661 studies, ultimately including 23 in the review. Our results showed that adaptation to reverberant speech is robust across diverse environments, experimental setups, speech units, and tasks, in noise-masked or unmasked conditions. The time course of adaptation is rapid, sometimes occurring in less than 1 s, but this can vary depending on the reverberation and noise levels of the acoustic environment. Adaptation is stronger in moderately reverberant rooms and minimal in rooms with very intense reverberation. While the mechanisms underlying the recalibration are largely unknown, adaptation to the direct-to-reverberant ratio-related changes in amplitude modulation appears to be the predominant candidate. However, additional factors need to be explored to provide a unified theory for the effect and its applications.

Various studies suggest the importance of sport-specific cognitive and perceptual abilities in soccer. However, the role of general perceptual-cognitive abilities and the relation of age respective to position have not been clarified for soccer in detail. Therefore, it was the objective of the present study to determine the relation of age and position to general perceptual-cognitive abilities. 178 highly talented male soccer players (mean age 16.2, age range 10 to 33 years) were involved. The participants performed computer-based sustained attention and anticipation (using Vienna Test System) tests. 139 subjects (mean age 16.6) took part in visual and acoustic reaction tests (using Talent Diagnostic System). The soccer players, subdivided into age and position groups, were recruited from a youth academy of a professional soccer club and played at the highest and 2nd highest national soccer competition for their age. Group differences were tested using analysis of variance. Correlations were analyzed for age and abilities. Significant correlations and group differences were found for age and sustained attention tasks. Significant differences for position groups were observed with regard to acoustic reaction time (ART). Further, we found statistical tendencies for group differences regarding the visual reaction time (VRT), indicating that midfielders outperform defenders and strikers in simple reaction tasks. Improved skills in sustained attention tasks resulted for defenders, who worked faster and more precisely in figural tasks. Regarding general anticipation tasks differences were not found. No group differences were found in basic anticipation tasks. Our study indicates that additional research is needed to further clarify the development of general perceptual-cognitive abilities and position-specific differences in the above abilities of highly talented soccer players.

Successful categorization requires listeners to represent the incoming sensory information, resolve the “blooming, buzzing confusion” inherent to noisy sensory signals, and leverage the accumulated evidence towards making a decision. Despite decades of intense debate, the neural systems underlying speech categorization remain unresolved. Here we assessed the neural representation and categorization of lexical tones by native Mandarin speakers (N = 31) across a range of acoustic and contextual variabilities (talkers, perceptual saliences, and stimulus-contexts) using functional magnetic imaging (fMRI) and an evidence accumulation model of decision-making. Univariate activation and multivariate pattern analyses reveal that the acoustic-variability-tolerant representations of tone category are observed within the middle portion of the left superior temporal gyrus (STG). Activation patterns in the frontal and parietal regions also contained category-relevant information that was differentially sensitive to various forms of variability. The robustness of neural representations of tone category in a distributed fronto-temporoparietal network is associated with trial-by-trial decision-making parameters. These findings support a hybrid model involving a representational core within the STG that operates dynamically within an extensive frontoparietal network to support the representation and categorization of linguistic pitch patterns.

[...]in the contribution of Krishnamurthy et al., the authors go beyond vision considering a model of the smell signal in the brain. Bertoni et al. propose a convolutional neural network architecture with biological constraints and show the emergence of spontaneous symmetries, analogously to those in the visual system, in the early layers during learning on natural images. [...]the work of Barbieri takes a more classical signal processing point of view and considers the problem of reconstructing an image that is downsampled in the space of a wavelet transform based on the SE(2) group.

It is a familiar experience to perceive a material object as maintaining a stable shape even though it projects differently shaped images on our retina as we move with respect to it, or as maintaining a stable color throughout changes in the way the object is illuminated. We also perceive sounds as maintaining constant timbre and loudness when the context and the spatial relations between us and the sound source change over time. But where does this perceptual invariance ‘come from’? What is it about our perceptual systems that makes them able to ‘transform’ incoming unstable and fluctuating sensory inputs into generally stable and coherent conscious experiences? And what exactly do we experience as invariant in cases like those described above? There are two main approaches to the Problem of Perceptual Invariance: the Local-Inferential approach and the Global-Structural approach. Although both approaches include an account of the sub-personal perceptual mechanisms ‘stabilizing’ variant and invariant components in incoming sensory stimulation and a proposal regarding the phenomenology of perceptual invariance, in this paper I argue that the latter provides a better solution to the problem overall.

Depth constancy is the ability to perceive a fixed depth interval in the world as constant despite changes in viewing distance and the spatial scale of depth variation. It is well known that the spatial frequency of depth variation has a large effect on threshold. In the first experiment, we determined that the visual system compensates for this differential sensitivity when the change in disparity is suprathreshold, thereby attaining constancy similar to contrast constancy in the luminance domain. In a second experiment, we examined the ability to perceive constant depth when the spatial frequency and viewing distance both changed. To attain constancy in this situation, the visual system has to estimate distance. We investigated this ability when vergence, accommodation and vertical disparity are all presented accurately and therefore provided veridical information about viewing distance. We found that constancy is nearly complete across changes in viewing distance. Depth constancy is most complete when the scale of the depth relief is constant in the world rather than when it is constant in angular units at the retina. These results bear on the efficacy of algorithms for creating stereo content. This article is part of the themed issue 'Vision in our three-dimensional world'.

Perceptual constancy refers to the fact that the perceived geometrical and physical characteristics of objects remain constant despite transformations of the objects such as rigid motion. Perceptual constancy is essential in everything we do, like recognition of familiar objects and scenes, planning and executing visual navigation, visuomotor coordination, and many more. Perceptual constancy would not exist without the geometrical and physical permanence of objects: their shape, size, and weight. Formally, perceptual constancy and permanence of objects are invariants, also known in mathematics and physics as symmetries. Symmetries of the Laws of Physics received a central status due to mathematical theorems of Emmy Noether formulated and proved over 100 years ago. These theorems connected symmetries of the physical laws to conservation laws through the least-action principle. We show how Noether's theorem is applied to mirror-symmetrical objects and establishes mental shape representation (perceptual conservation) through the application of a simplicity (least-action) principle. This way, the formalism of Noether's theorem provides a computational explanation of the relation between the physical world and its mental representation.