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Copyright of Canadian Journal of Anaesthesia / Journal Canadien d'Anesthésie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• The Poggendorff illusion decreases with age in typically developing children. • Maturation of the illusion depends on sensory and cognitive development. • Two theories on the illusion, which are not mutually exclusive, are supported. We examined how the strength of the Poggendorff illusion changes with age in typically developing children. To this end, we recruited children aged 6 to 14 years and quantified the degree to which they experienced the illusion. The illusion was strongest in the youngest children and decreased with age logarithmically—reaching adult levels (as established by an earlier study) by 21.6 years, as determined by nonlinear interpolation. We also measured the ability to align two lines together in a nonillusory condition, receptive language, and abstract reasoning to determine whether changes in illusion strength were also associated with these factors. Alignment-matching abilities, receptive language, and abstract reasoning increased with age. However, only receptive language and abstract reasoning were correlated with illusion strength. Abilities in alignment matching were not related to illusion strength and reached adult levels (as established by a previous study) earlier at 14.7 years, as determined by nonlinear interpolation. A multiple regression analysis further revealed that receptive language and abstract reasoning did not contribute beyond their shared variance with age. Based on these findings, we suggest that the illusion is exaggerated in early development and attenuates as low-level and high-level processes mature. The theoretical implications of these findings are discussed. [ABSTRACT FROM AUTHOR]

The size-weight illusion is a phenomenon where a smaller object is perceived heavier than an equally weighted larger object. The sensorimotor mismatch theory proposed that this illusion occurs because of a mismatch between efferent motor commands and afferent sensory feedback received when lifting large and small objects (i.e., the application of too little and too much lifting force, respectively). This explanation has been undermined by studies demonstrating a separation between the perceived weight of objects and the lifting forces that are applied on them. However, this research suffers from inconsistencies in the choice of lifting force measures reported. Therefore, we examined the contribution of sensorimotor mismatch in the perception of weight in the size-weight illusion and in non-size-weight illusion stimuli and evaluated the use of a lifting force aggregate measure comprising the four most common lifting force measures used in previous research. In doing so, the sensorimotor mismatch theory was mostly supported. In a size-weight illusion experiment, the lifting forces correlated with weight perception and, contrary to some earlier research, did not adapt over time. In a non-size-weight illusion experiment, switches between lifting light and heavy objects resulted in perceiving the weight of these objects differently compared to no switch trials, which mirrored differences in the manner participants applied forces on the objects. Additionally, we reveal that our force aggregate measure can allow for a more sensitive and objective examination of the effects of lifting forces on objects. [ABSTRACT FROM AUTHOR]

Typically developing adults with low and high Autism Spectrum Quotient (AQ) scores made rapid social evaluations of neutral faces when these were primed by briefly presented emotional faces. High AQ participants rated neutral faces as more threatening than low AQ participants, regardless of the prime condition. Both groups rated target neutral faces as more threatening with fearful compared with neutral primes, while neither group demonstrated an effect of happy primes on the ratings of neutral target faces. These results demonstrate subtle anomalies in rapid visual processing of emotional faces across the broader autism spectrum. They suggest that higher autism traits may be associated with a generalized threat bias in rapid social evaluations. [ABSTRACT FROM AUTHOR]

Size constancy is the ability to perceive objects as remaining constant in size regardless of their distance from the observer. Emmert's law demonstrates that viewing distance determines the perceived size of afterimages according to the amount of depth cues that are available. Using an afterimage paradigm, we examined to what extent removing stereopsis and other depth cues affects size–distance scaling. Thirty participants 'projected' afterimages onto a surface presented at different distances under binocular, monocular, and eyes-closed conditions. The perceived size of the afterimages closely followed the size–distance scaling predictions made by Emmert's law under binocular testing conditions, when all depth cues were available. In contrast, monocular testing decreased adherence to Emmert's law, while the eyes-closed condition resulted in a greater breakdown of size–distance scaling. Because we used an afterimage paradigm, this study provides the first demonstration of how perceived size is modulated by the availability of depth cues under conditions with a constant retinal image stimulus. [ABSTRACT FROM AUTHOR]

The presence of pictorial depth cues in virtual environments is important for minimising distortions driven by unnatural viewing conditions (e.g., vergence-accommodation conflict). Our aim was to determine how different pictorial depth cues affect size constancy in virtual environments under binocular and monocular viewing conditions. We systematically removed linear perspective cues and textures of a hallway in a virtual environment. The experiment was performed using the method of constant stimuli. The task required participants to compare the size of 'far' (10 m) and 'near' (5 m) circles displayed inside a virtual environment with one or both or none of the pictorial depth cues. Participants performed the experiment under binocular and monocular viewing conditions while wearing a virtual reality headset. ANOVA revealed that size constancy was greater for both the far and the near circles in the virtual environment with pictorial depth cues compared to the one without cues. However, the effect of linear perspective cues was stronger than textures, especially for the far circle. We found no difference between the binocular and monocular viewing conditions across the different virtual environments. We conclude that linear perspective cues exert a stronger effect than textures on the perceptual rescaling of far stimuli placed in the virtual environment, and that this effect does not vary between binocular and monocular viewing conditions. [ABSTRACT FROM AUTHOR]

The article discusses the relation between primary visual cortex and visual phenomenology of object size. Topics discussed include studies related to functional magnetic resonance imaging (fMRI), optical illusion displays in experiments and patterns of activation in the primary visual cortex. Also mentions that a behavioral experiment wa performed to determine exposure to an adapter stimulus causing presented test stimulus as larger or smaller than an identically sized.

The relationship between autistic traits, stress, and anxiety experienced by the general population was investigated using an adult sample that evaluated the suitability of three theoretical models proposed by Green and Ben-Sasson. Participants completed online questionnaires that were analysed using structural equation modelling and partial correlation analyses. Of the models tested, the model that proposed SOR and stress as mediators of the relationship between autistic traits and anxiety was able to explain the variance in the data better than the other models. Based on these findings, we suggest that sensory neutral environments should be considered for the prevention and management of anxiety and stress symptoms for people in the general population with higher levels of autistic traits. [ABSTRACT FROM AUTHOR]

This article reviews theoretical and empirical arguments for and against various theories that explain the classic Ponzo illusion and its variants from two different viewpoints concerning the role of perceived depth in size distortions. The first viewpoint argues that all Ponzo-like illusions are driven by perceived depth. The second viewpoint argues that the classic Ponzo illusion is unrelated to depth perception. This review will give special focus to the first viewpoint and consists of three sections. In the first section, the role of the number of pictorial depth cues and previous experience in the strength of all Ponzo-like illusions are discussed. In the second section, we contrast the first viewpoint against the theories that explain the classic Ponzo illusion with mechanisms that are unrelated to depth perception. In the last section, we propose a Bayesian-motivated reconceptualization of Richard Gregory's misapplied size constancy theory that explains Ponzo-variant illusions in terms of prior information and prediction errors. The new account explains why some studies have provided inconsistent evidence for misapplied size constancy theory. [ABSTRACT FROM AUTHOR]

There is a growing body of literature demonstrating the relationship between the activation of sensorimotor processes in object recognition. It is unclear, however, if these processes are influenced by the differences in how real (3D) tools and two-dimensional (2D) images of tools are processed by the brain. Here, we examined if these differences could influence the naming of tools. Participants were presented with a prime stimulus that was either a picture of a tool, or a real tool, followed by a target stimulus that was always a real tool. They were then required to name each tool as they appeared. The functional use action required by the target tool was either the same (i.e., squeegee–paint roller) or different (i.e. knife–whisk) to the prime. We found that the format in which the prime tool was presented (i.e., a picture or real tool) had no influence on the participants' response times to naming the target tool. Furthermore, participants were faster at naming target tools relative to prime tools when the exact same tool was presented as both the prime and target. There was no difference in response times to naming the target tool relative to the prime when they were different tools, regardless of whether the tools' functional actions were the same or different. We also found more errors in naming target tools relative to the primes when different tools had a different functional action compared to when the same tool was presented as both the prime and the target. Taken together, our results highlight that the functional actions associated with tools do not facilitate or interfere with the recognition of tools for the purposes of naming. The theoretical implications of these results are discussed. [ABSTRACT FROM AUTHOR]

We examined whether functional and structural variability in the primary visual area (V1) correlated with autism traits. Twenty-nine participants (16 males; MAge = 26.4 years, SDAge = 4.0 years) completed the autism-spectrum quotient (AQ) questionnaire prior to a magnetic resonance imaging session. The total AQ scores was used to assess the degree of self-reported autism traits. The average functional activation in V1 to visual stimulation and its average grey-matter thickness were calculated. There were no correlations between functional activation in V1 and autism traits. Conversely, grey-matter thickness of the left but not the right V1 correlated with autism traits. We conclude that structural changes in the left V1 could be a marker for the presence of autism traits. [ABSTRACT FROM AUTHOR]