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For this study, we started from the observation that the poor adequacy of a script to the requirements of the human visual system strongly impacts some aspects of reading expertise (e.g., fluent reading). Here we investigated another of these aspects, namely the ability to break mirror invariance, which makes it hard for readers to ignore the mirrored contrasts of letters even if this hinders performance. In particular, we hypothesized that this ability would be preserved for the visually presented letters of the Braille alphabet despite their poor fit to the constraints of the human visual system, as it did for congenital Braille readers when they explored the same letters through the tactile modality (de Heering, Collignon, & Kolinsky, 2018). To test so, we measured visual Braille readers' mirror costs, indexing for their difficulty to consider mirrored items as identical compared to strictly identical items, for three materials: Braille letters, geometrical shapes and Latin letters, which invariant properties are typically considered as having been selected through cultural evolution because they match the requirements of the visual system. Contrary to people having never experienced Braille, Braille readers' mirror cost was of the same magnitude for Latin letters and Braille letters and steadily increased the more they had experience with the latter material. Both these costs were also stronger than what was observed for geometrical shapes. Overall these results suggest that the poor adequacy of the Braille alphabet to the visual system does not impede Braille readers to break mirror invariance for the Braille material. [ABSTRACT FROM AUTHOR]

Humans form mental images and manipulate them in ways that mirror physical transformations of objects. Studies of nonhuman animals will inform our understanding of the evolution and distribution among species of mental imagery. Across three experiments, we found mostly converging evidence that rhesus monkeys formed and rotated mental images. In Experiment 1, monkeys discriminated rotations of sample images from mirror images, and showed longer response latencies with greater rotation as is characteristic of human mental rotation. In Experiment 2 monkeys used a rotation cue that indicated how far to mentally rotate sample images before tests, indicating a precision of better than 30° in discriminating rotations. Experiment 3 yielded mixed evidence on whether the rotation cue shortened decision times as has been found in humans. These results show that rhesus monkeys manipulate mental images. [ABSTRACT FROM AUTHOR]

Highlights: [•] We test a non-retinotopic, object-centered mechanism in exogenous attention. [•] Performance is enhanced at the non-retinotopic, same relative location as the cue. [•] Exogenous attention generalizes across both translation and mirror reflection. [•] These results reveal a object-centered structural mechanism in exogenous attention. [•] Provides an attentional correlate of perceptual generalization across mirror images. [Copyright &y& Elsevier]

Abstract: Participants decided when somebody, Janine, could see their face in a horizontal row of adjacent mirrors mounted flat on the same wall. They saw real mirrors and a shop-dummy representing Janine. Such coplanar mirrors reflect different, non-overlapping areas of a scene. However, almost everybody made an unexpected error: they claimed that Janine would see her face reflected in multiple mirrors simultaneously. They therefore responded as if each mirror showed similar information and thus grossly overestimated how much each mirror revealed. Further studies established that this multiple reflection error also occurred for vertical rows of mirrors and for different areas of a single, large mirror. The error was even common if the participant themselves sat in front of a set of covered-up mirrors and indicated where they would be able to see their own reflection. In the latter case, people often made multiple reflection errors despite having seen all the mirrors uncovered immediately before they responded. People’s gross overestimation of how much of a scene a mirror reflects and their inability to learn to correct this false belief explains why, despite a lifetime’s experience of mirrors, they incorrectly think they will see themselves in all nearby mirrors. [Copyright &y& Elsevier]

Abstract: Perceiving the orientation of objects is important for interacting with the world, yet little is known about the mental representation or processing of object orientation information. The tendency of humans and other species to confuse mirror images provides a potential clue. However, the appropriate characterization of this phenomenon is not entirely clear, in part because the stimuli used in most previous studies were not adequate for distinguishing various forms of mirror-image and non-mirror-image error. In the present study we explore the nature of mirror-image confusion and what the phenomenon can reveal about object-orientation representations. We report several experiments in which participants reported the orientations of pictures. In all of the experiments mirror-reflection errors were more frequent than other orientation errors. However, whereas mirror-image confusion has previously been described as a tendency to confuse stimuli that are related by reflection across an extrinsic (usually vertical) axis, the vast majority of mirror-image errors in our experiments were reflections across an object axis. This finding calls into question several hypotheses proposed to explain mirror-image confusion. We describe a coordinate-system orientation representation (COR) hypothesis that can account for our results (). COR assumes that orientation representations map an object-centered reference frame onto a reference frame extrinsic to the object, with this mapping specified by several parameters. According to COR, mirror-image confusions and other orientation errors arise from failures in representing or processing specific parameters. Considered in light of COR, our results suggest that orientation representations are compositional, and that object-centered reference frames play a central role in orientation representation. [Copyright &y& Elsevier]

Abstract: As observed by Gombrich [Gombrich, E. H. (1960). Art and illusion. Oxford: Phaidon Press], we confirm that most people are unaware of the size of their own image on mirrors. Specifically we have documented the knowledge that people have of the size of their own head and of the size of the mirror image of their own head. In addition we have explored naive beliefs about how the size of mirror images changes with distance. The main pattern of findings is consistent with a focus on target distance and a difficulty in factoring the observer''s vantage point correctly when people reason about the problem. The issue of information about vantage point is discussed in relation to other literatures. [Copyright &y& Elsevier]

Learning a script with mirrored graphs (e.g., d ≠ b) requires overcoming the evolutionary-old perceptual tendency to process mirror images as equivalent. Thus, breaking mirror invariance offers an important tool for understanding cultural re-shaping of evolutionarily ancient cognitive mechanisms. Here we investigated the role of script (i.e., presence vs. absence of mirrored graphs: Latin alphabet vs. Tamil) by revisiting mirror-image processing by illiterate, Tamil monoliterate, and Tamil-Latin-alphabet bi-literate adults. Participants performed two same-different tasks (one orientation-based, another shape-based) on Latin-alphabet letters. Tamil monoliterate were significantly better than illiterate and showed good explicit mirror-image discrimination. However, only bi-literate adults fully broke mirror invariance: slower shape-based judgments for mirrored than identical pairs and reduced disadvantage in orientation-based over shape-based judgments of mirrored pairs. These findings suggest learning a script with mirrored graphs is the strongest force for breaking mirror invariance. [ABSTRACT FROM AUTHOR]