A tutorial on the physics of light and image shading.

This paper provides an overview of the many different ways that light interacts with surfaces in the natural environment to provide useful information for visual perception. It begins with a discussion of how the concept of light has evolved over the course of human history. It then considers a wide variety of optical phenomena including Lambert's laws of illumination, the effects of microscopic surface structure on patterns of reflection, the bidirectional reflectance distribution function, the refraction of transmitted light, chromatic dispersion, thin film interference, sub-surface scattering, the Fresnel effects, indirect illumination from multiple reflections, caustics, and the structure of the light field.

Building language learning: Relations between infant attention and social contingency in the first year of life.

In Western societies, social contingency, or prompt and meaningful back-and-forth exchanges between infant and caregiver, is a powerful feature of the early language environment. Research suggests that infants with better attentional skills engage in more social contingency during interactions with adults and, in turn, social contingency supports infant attention. This reciprocity is theorized to build infant language skills as the adult capitalizes on and extends the infant's attention during socially contingent interactions.

The effects of socioeconomic status on working memory in childhood are partially mediated by intersensory processing of audiovisual events in infancy.

Socioeconomic status (SES) is a well-established predictor of individual differences in childhood language and cognitive functioning, including executive functions such as working memory. In infancy, intersensory processing-selectively attending to properties of events that are redundantly specified across the senses at the expense of non-redundant, irrelevant properties-also predicts language development. Our recent research demonstrates that individual differences in intersensory processing in infancy predict a variety of language outcomes in childhood, even after controlling for SES.

Infant distractibility from social events mediates the relation between maternal responsiveness and infant language outcomes.

Research demonstrates that contingent and appropriate maternal responsiveness to infant requests and bids for attention leads to better language outcomes. Research also indicates that infants who are less distracted by irrelevant competing stimulation and attend efficiently to audiovisual social events (e.g.

Effects of English versus Spanish language exposure on basic multisensory attention skills across 3 to 36 months of age.

Recent research has demonstrated that individual differences in infant attention to faces and voices of women speaking predict language outcomes in childhood. These findings have been generated using two new audiovisual attention assessments appropriate for infants and young children, the Multisensory Attention Assessment Protocol (MAAP) and the Intersensory Processing Efficiency Protocol (IPEP). The MAAP and IPEP assess three basic attention skills (sustaining attention, shifting/disengaging, intersensory matching), as well as distractibility, deployed in the context of naturalistic audiovisual social (women speaking English) and nonsocial events (objects impacting a surface).

Qualitative perception of 3D shape from patterns of luminance curvature.

A new source of information is proposed for the perception of three-dimensional (3D) shape from shading that identifies surface concavities from the curvature of the luminance field. Two experiments measured the abilities of human observers to identify concavities on smoothly curved shaded surfaces depicted with several different patterns of illumination and several different material properties. Observers were required to identify any apparent concavities along designated cross sections of the depicted objects and to mark each concavity with an adjustable dot.

Intersensory processing of faces and voices at 6 months predicts language outcomes at 18, 24, and 36 months of age.

Intersensory processing of social events (e.g., matching sights and sounds of audiovisual speech) is a critical foundation for language development.

Individual Differences in Multisensory Attention Skills in Children with Autism Spectrum Disorder Predict Language and Symptom Severity: Evidence from the Multisensory Attention Assessment Protocol (MAAP).

Children with autism spectrum disorders (ASD) show atypical attention, particularly for social events. The new Multisensory Attention Assessment Protocol (MAAP) assesses fine-grained individual differences in attention disengagement, maintenance, and audiovisual matching for social and nonsocial events. We investigated the role of competing stimulation on attention, and relations with language and symptomatology in children with ASD and typical controls.

Intersensory matching of faces and voices in infancy predicts language outcomes in young children.

Parent language input is a well-established predictor of child language development. Multisensory attention skills (MASks; intersensory matching, shifting and sustaining attention to audiovisual speech) are also known to be foundations for language development. However, due to a lack of appropriate measures, individual differences in these skills have received little research focus.

Are mirror-symmetric objects of special importance for 3D shape perception? A reply to Sawada and Pizlo (2022).

Yu, Todd, and Petrov (2021) and Yu, Petrov, and Todd (2021) investigated failures of shape constancy that occur when objects are viewed stereoscopically at different distances. Although this result has been reported previously with simple objects such as pyramids or cylinders, we examined more complex objects with bilateral symmetry to test the claim by Li, Sawada, Shi, Kwon, and Pizlo (2011) that the perception of those objects is veridical. Sawada and Pizlo (2022) offer several criticisms of our experiments, but they seem to suggest that the concept of shape is defined by what is computable by their model.

Remote Data Collection During a Pandemic: A New Approach for Assessing and Coding Multisensory Attention Skills in Infants and Young Children.

In early 2020, in-person data collection dramatically slowed or was completely halted across the world as many labs were forced to close due to the COVID-19 pandemic. Developmental researchers who assess looking time (especially those who rely heavily on in-lab eye-tracking or live coding techniques) were forced to re-think their methods of data collection. While a variety of remote or online platforms are available for gathering behavioral data outside of the typical lab setting, few are specifically designed for collecting and processing looking time data in infants and young children.

The many facets of shape.

Shape is an interesting property of objects because it is used in ordinary discourse in ways that seem to have little connection to how it is typically defined in mathematics. The present article describes how the concept of shape can be grounded within Euclidean and non-Euclidean geometry and also to human perception. It considers the formal methods that have been proposed for measuring the differences among shapes and how the performance of those methods compares with shape difference thresholds of human observers.

Bilateral Symmetry Has No Effect on Stereoscopic Shape Judgments.

A single experiment is reported that measured the apparent stereoscopic shapes of symmetric and asymmetric objects at different viewing distances. The symmetric stimuli were specifically designed to satisfy the minimal conditions for computing veridical shape from symmetry. That is to say, they depicted complex, bilaterally symmetric, plane-faced polyhedra whose symmetry planes were oriented at an angle of 45° relative to the line of sight.

Failures of stereoscopic shape constancy over changes of viewing distance and size for bilaterally symmetric polyhedra.

Two shape matching experiments examined the effects of viewing distance and object size on observers' judgments of 3D metric shape under binocular viewing. Unlike previous studies on this topic, the stimuli were specifically designed to satisfy the minimal conditions for computing veridical shape from symmetry. Concretely, the stimuli were complex, mirror-symmetric polyhedra whose symmetry planes were oriented at an angle of 45o relative to the line of sight in a shape-matching task.

On the Ambient Optic Array: James Gibson's Insights About the Phenomenon of Chiaroscuro.

In 1966, James Gibson first presented his theory of the ambient optic array, and he proposed a new field of ecological optics that he hoped would advance our knowledge on this topic. This study will consider how his ideas have largely come to fruition over the past 50 years. It reviews the research on the visual perception of three-dimensional shape from shading, the effects of ambient light from surface interreflections on observers' perceptions, the perception of the light field, and the perception of surface materials.

Contours produced by internal specular interreflections provide visual information for the perception of glass materials.

Two experiments are reported that investigated how the perceptual identification of glass is influenced by banding contours formed by internal specular interreflections within glass materials. Observers made material categorization judgments for images depicting glass, chrome, shiny black and shiny white objects, and for contour drawings that were created by edge filtering images of glass, chrome or textured objects. Observers rated each stimulus by adjusting four sliders to indicate their confidence that the depicted material was glass, metal, shiny black, or something else, and these adjustments were constrained so that the sum of all four settings was always 100%.

Effects of illumination on the categorization of shiny materials.

The present research was designed to examine how patterns of illumination influence the perceptual categorization of metal, shiny black, and shiny white materials. The stimuli depicted three possible objects that were illuminated by five possible high-dynamic-range imaging light maps, which varied in their overall distributions of illuminant directions and intensities. The surfaces included a low roughness chrome material, a shiny black material, and a shiny white material with both diffuse and specular components.

Reflections on glass.

An important phenomenon in the study of human perception is the ability of observers to identify different types of surface materials. The present article will consider a wide range of factors that can influence the perceptual identification of glass, including the structural complexity of an object, whether it is hollow or solid, and the pattern of illumination. Several illumination techniques used in the field of photography are described, and examples are provided to show how they interact with structural complexity.

The Multisensory Attention Assessment Protocol (MAAP): Characterizing individual differences in multisensory attention skills in infants and children and relations with language and cognition.

Multisensory attention skills provide a crucial foundation for early cognitive, social, and language development, yet there are no fine-grained, individual difference measures of these skills appropriate for preverbal children. The Multisensory Attention Assessment Protocol (MAAP) fills this need. In a single video-based protocol requiring no language skills, the MAAP assesses individual differences in three fundamental building blocks of attention to multisensory events-the duration of attention maintenance, the accuracy of intersensory (audiovisual) matching, and the speed of shifting-for both social and nonsocial events, in the context of high and low competing visual stimulation.

Assessing individual differences in the speed and accuracy of intersensory processing in young children: The intersensory processing efficiency protocol.

Detecting intersensory redundancy guides cognitive, social, and language development. Yet, researchers lack fine-grained, individual difference measures needed for studying how early intersensory skills lead to later outcomes. The intersensory processing efficiency protocol (IPEP) addresses this need.

The visual perception of metal.

The present research was designed to examine how the presence or absence of ambient light influences the appearance of metal. The stimuli depicted three possible objects that were illuminated by three possible patterns of illumination. These were generated by a single point light source, two rectangular area lights, or projecting light onto a translucent white box that contained the object (and the camera) so that the object would be illuminated by ambient light in all directions.

Binocular stereo acuity affects monocular three-dimensional shape perception in patients with strabismus.

Background/aims: To evaluate the perception of three-dimensional (3D) shape in patients with strabismus and the contributions of stereopsis and monocular cues to this perception.

Methods: Twenty-one patients with strabismus with and 20 without stereo acuity as well as 25 age-matched normal volunteers performed two tasks: (1) identifying the closest vertices of 3D shapes from monocular shading (3D-SfS), texture (3D-SfT) or motion cues (3D-SfM) and from binocular disparity (3D-SfD), (2) discriminating 1D elementary features of these cues.

Results: Discrimination of the elementary features of luminance, texture and motion did not differ across groups.

Temporal Dependency and the Structure of Early Looking.

Although looking time is used to assess infant perceptual and cognitive processing, little is known about the temporal structure of infant looking. To shed light on this temporal structure, 127 three-month-olds were assessed in an infant-controlled habituation procedure and presented with a pre-recorded display of a woman addressing the infant using infant-directed speech. Previous individual look durations positively predicted subsequent look durations over a six look window, suggesting a temporal dependency between successive infant looks.

Enhanced attention to speaking faces versus other event types emerges gradually across infancy.

The development of attention to dynamic faces versus objects providing synchronous audiovisual versus silent visual stimulation was assessed in a large sample of infants. Maintaining attention to the faces and voices of people speaking is critical for perceptual, cognitive, social, and language development. However, no studies have systematically assessed when, if, or how attention to speaking faces emerges and changes across infancy.

The darker-is-deeper heuristic for the perception of 3D shape from shading: Is it perceptually or ecologically valid?

The darker-is-deeper heuristic was originally proposed by Langer and Zucker (1994) for approximating 3D shape from shading under conditions of diffuse illumination that typically occur for outdoor scenes on a cloudy day, and it is based on the assumption that vignetting is the primary source of luminance variation under those conditions. It was later rejected as a model of human perception by Langer and Bülthoff (2000), because points in concavities that appear to be the deepest are most often located on local luminance maxima. Despite that result, this heuristic has continued to be described in the literature as a viable model of human perception (e.