How to construct liquid-crystal spectacles to control vision of real-world objects and environments.

A major challenge in studying naturalistic vision lies in controlling stimulus and scene viewing time. This is especially the case for studies using real-world objects as stimuli (rather than computerized images) because real objects cannot be "onset" and "offset" in the same way that images can be. Since the late 1980s, one solution to this problem has been to have the observer wear electro-optic spectacles with computer-controlled liquid-crystal lenses that switch between transparent ("open") and translucent ("closed") states. Unfortunately, the commercially available glasses (PLATO Visual Occlusion Spectacles) command a high price tag, the hardware is fragile, and the glasses cannot be customized. This led us to explore how to manufacture liquid-crystal occlusion glasses in our own laboratory. Here, we share the products of our work by providing step-by-step instructions for researchers to design, build, operate, and test liquid-crystal glasses for use in experimental contexts. The glasses can be assembled with minimal technical knowledge using readily available components, and they can be customized for different populations and applications. The glasses are robust, and they can be produced at a fraction of the cost of commercial alternatives. Tests of reliability and temporal accuracy show that the performance of our laboratory prototype was comparable to that of the PLATO glasses. We discuss the results of our work with respect to implications for promoting rigor and reproducibility, potential use cases, comparisons with other liquid-crystal shutter glasses, and how users can find information regarding future updates and developments.

A priming study on naming real versus pictures of tools.

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.

Do infants show knowledge of the familiar size of everyday objects?

The current study aimed to examine the age at which infants exhibit knowledge of the familiar size of common everyday objects. A total of 65 7- and 12-month-old infants were presented with familiar-sized and novel-sized (i.e., larger or smaller than the familiar size) common everyday objects (i.e., pacifiers and sippy cups), which were placed out of their reach. Both 7- and 12-month-olds' first looks were more frequently directed toward physically larger objects irrespective of whether they were familiar- or novel-sized objects. This finding indicates that initial visual orientation is contingent on the magnitude of the absolute physical size of an object. However, when the entire duration of presentation of the objects (i.e., 10 s) was examined, 12-month-olds' mean looking durations were found to be longer for novel-sized objects than for familiar-sized objects. Thus, although infants in both age groups were able to discern the physical sizes of objects, only 12-month-olds could successfully discriminate between the familiar and novel sizes of everyday objects. Notably, 12-month-olds demonstrated knowledge of familiar size even though the test objects were out of their reach and, consequently, unamenable to manual exploration.

"Real-life" continuous flash suppression (CFS)-CFS with real-world objects using augmented reality goggles.

Continuous flash suppression (CFS) is a popular method for suppressing visual stimuli from awareness for relatively long periods. Thus far, this method has only been used for suppressing two-dimensional images presented on screen. We present a novel variant of CFS, termed "real-life" CFS, in which a portion of the actual immediate surroundings of an observer-including three-dimensional, real-life objects-can be rendered unconscious. Our method uses augmented reality goggles to present subjects with CFS masks to the dominant eye, leaving the nondominant eye exposed to the real world. In three experiments we demonstrated that real objects can indeed be suppressed from awareness for several seconds, on average, and that the suppression duration is comparable to that obtained using classic, on-screen CFS. As supplementary information, we further provide an example of experimental code that can be modified for future studies. This technique opens the way to new questions in the study of consciousness and its functions.

Dependence of behavioral performance on material category in an object-grasping task with monkeys.

Material perception is an essential part of our cognitive function that enables us to properly interact with our complex daily environment. One important aspect of material perception is its multimodal nature. When we see an object, we generally recognize its haptic properties as well as its visual properties. Consequently, one must examine behavior using real objects that are perceived both visually and haptically to fully understand the characteristics of material perception. As a first step, we examined whether there is any difference in the behavioral responses to different materials in monkeys trained to perform an object grasping task in which they saw and grasped rod-shaped real objects made of various materials. We found that the monkeys' behavior in the grasping task, which was measured based on the success rate and the pulling force, differed depending on the material category. Monkeys easily and correctly grasped objects of some materials, such as metal and glass, but failed to grasp objects of other materials. In particular, monkeys avoided grasping fur-covered objects. The differences in the behavioral responses to the material categories cannot be explained solely based on the degree of familiarity with the different materials. These results shed light on the organization of multimodal representation of materials, where their biological significance is an important factor. In addition, a monkey that avoided touching real fur-covered objects readily touched images of the same objects presented on a CRT display. This suggests that employing real objects is important when studying behaviors related to material perception. NEW & NOTEWORTHY We tested monkeys using an object-grasping task in which monkeys saw and grasped rod-shaped real objects made of various materials. We found that the monkeys' behavior differed dramatically across the material categories and that the behavioral differences could not be explained solely based on the degree of familiarity with the different materials. These results shed light on the organization of multimodal representation of materials, where the biological significance of materials is an important factor.

Priming tool actions: Are real objects more effective primes than pictures?

Humans are faster to grasp an object such as a tool if they have previewed the same object beforehand. This priming effect is strongest when actors gesture the use of the tool rather than simply move it, possibly because the previewed tool activates action-specific routines in dorsal-stream motor networks. Here, we examined whether real tools, which observers could physically act upon, serve as more potent primes than two-dimensional images of tools, which do not afford physical action. Participants were presented with a prime stimulus that could be either a real tool or a visually matched photograph of a tool. After a brief delay, participants interacted with a real tool target, either by 'grasping to move,' or 'grasping to use' it. The identities of the prime and target tools were either the same (congruent trials; e.g., spatula-spatula) or different (incongruent trials; e.g., whisk-spatula). As expected, participants were faster to initiate grasps during trials when they had to move the tool rather than gesture its use. Priming effects were observed for grasp-to-use, but not grasp-to-move, responses. Surprisingly, however, both pictures of tools and real tools primed action responses equally. Our results indicate that tool priming effects are driven by pictorial cues and their implied actions, even in the absence of volumetric cues that reflect the tangibility and affordances of the prime.

Viewpoint adaptation revealed potential representational differences between 2D images and 3D objects.

For convenience and experimental control, cognitive science has relied largely on images as stimuli rather than the real, tangible objects encountered in the real world. Recent evidence suggests that the cognitive processing of images may differ from real objects, especially in the processing of spatial locations and actions, thought to be mediated by the dorsal visual stream. Perceptual and semantic processing in the ventral visual stream, however, has been assumed to be largely unaffected by the realism of objects. Several studies have found that one key difference accounting for differences between real objects and images is actability; however, less research has investigated another potential difference - the three-dimensional nature of real objects as conveyed by cues like binocular disparity. To investigate the extent to which perception is affected by the realism of a stimulus, we compared viewpoint adaptation when stimuli (a face or a kettle) were 2D (flat images without binocular disparity) vs. 3D (i.e., real, tangible objects or stereoscopic images with binocular disparity). For both faces and kettles, adaptation to 3D stimuli induced stronger viewpoint aftereffects than adaptation to 2D images when the adapting orientation was rightward. A computational model suggested that the difference in aftereffects could be explained by broader viewpoint tuning for 3D compared to 2D stimuli. Overall, our finding narrowed the gap between understanding the neural processing of visual images and real-world objects by suggesting that compared to 2D images, real and simulated 3D objects evoke more broadly tuned neural representations, which may result in stronger viewpoint invariance.

Sex-related preferences for real and doll faces versus real and toy objects in young infants and adults.

Findings of previous studies demonstrate sex-related preferences for toys in 6-month-old infants; boys prefer nonsocial or mechanical toys such as cars, whereas girls prefer social toys such as dolls. Here, we explored the innate versus learned nature of this sex-related preferences using multiple pictures of doll and real faces (of men and women) as well as pictures of toy and real objects (cars and stoves). In total, 48 4- and 5-month-old infants (24 girls and 24 boys) and 48 young adults (24 women and 24 men) saw six trials of all relevant pairs of faces and objects, with each trial containing a different exemplar of a stimulus type. The infant results showed no sex-related preferences; infants preferred faces of men and women regardless of whether they were real or doll faces. Similarly, adults did not show sex-related preferences for social versus nonsocial stimuli, but unlike infants they preferred faces of the opposite sex over objects. These results challenge claims of an innate basis for sex-related preferences for toy real stimuli and suggest that sex-related preferences result from maturational and social development that continues into adulthood.

Manual exploration of objects is related to 7-month-old infants' visual preference for real objects.

The present study examined whether infants' visual preferences for real objects and pictures are related to their manual object exploration skills. Fifty-nine 7-month-old infants were tested in a preferential looking task with a real object and its pictorial counterpart. All of the infants also participated in a manual object exploration task, in which they freely explored five toy blocks. Results revealed a significant positive relationship between infants' haptic scan levels in the manual object exploration task and their gaze behavior in the preferential looking task: The higher infants' haptic scan levels, the longer they looked at real objects compared to pictures. Our findings suggest that the specific exploratory action of haptically scanning an object is associated with infants' visual preference for real objects over pictures.

The Treachery of Images: How Realism Influences Brain and Behavior.

Although the cognitive sciences aim to ultimately understand behavior and brain function in the real world, for historical and practical reasons, the field has relied heavily on artificial stimuli, typically pictures. We review a growing body of evidence that both behavior and brain function differ between image proxies and real, tangible objects. We also propose a new framework for immersive neuroscience to combine two approaches: (i) the traditional build-up approach of gradually combining simplified stimuli, tasks, and processes; and (ii) a newer tear-down approach that begins with reality and compelling simulations such as virtual reality to determine which elements critically affect behavior and brain processing.

The influence of object similarity on real object-based attention: The disassociation of perceptual and semantic similarity.

Perceptual and semantic similarity have an impact on object-based attention for the geometric objects. However, no previous studies have disassociated perceptual properties from the semantic ones of real objects that combine perceptual and semantic properties. It is unclear whether the perceptual and semantic similarity of real objects jointly or independently guides attentional deployment. The aim of the present study was to explore the influence of object similarity on object-based attention by using a variant of the two-rectangle paradigm and disassociating the perceptual and semantic similarity of real objects. The results indicated that when the semantic of objects was similar, the object-based effect was larger for the perceptually dissimilar condition than for the perceptually similar condition, because of slower response to invalid different-object location in a dissimilar condition. Moreover, when the perception of objects was similar, the object-based effect was larger for the semantically dissimilar condition than for the semantically similar condition, due to slower response to invalid different-object location in a dissimilar condition. These results suggest that perceptual and semantic similarity can independently guide attentional allocation to real objects and the similarity may constrain the object-based attention in a way of grouping. The current study implies that the attentional prioritization hypothesis is more flexible and effective to explain the real object-based attention and also has some implication to advertising design.

Manual Grasparatus: A nifty tool for presenting real objects in fMRI research.

One of the greatest challenges in functional magnetic resonance imaging (fMRI) research using real objects as stimuli is their timely delivery and (pseudo)randomized presentation. To this end, we designed an apparatus which solves the majority of problems that fMRI researchers may encounter during testing. The display apparatus - here: delivering objects for manual exploration and grasping (hence the "Grasparatus") - is equipped with semi-attachable stimulus belts and, therefore, allows for presentation of numerous 3D objects in a pre-ordered sequence. Although the presentation is controlled manually and synchronized with fMRI scanning events via commands delivered to the experimenter, it is very reliable in conveying targets to their destination in different configurations and numbers. The stimuli are easily accessible to study participants either for manual or simple visual interactions because the device is highly adjustable. The main advantages of using this apparatus involve: •The easiness of its setup prior to a study and simplicity of its control during experimental functional MRI runs.•The possibility to use real size, magnet-friendly objects, firmly or semi-attached, so that different interactions are possible.•Fast exchange of stimulus sets between runs.

Getting a grip on reality: Grasping movements directed to real objects and images rely on dissociable neural representations.

In the current era of touchscreen technology, humans commonly execute visually guided actions directed to two-dimensional (2D) images of objects. Although real, three-dimensional (3D), objects and images of the same objects share high degree of visual similarity, they differ fundamentally in the actions that can be performed on them. Indeed, previous behavioral studies have suggested that simulated grasping of images relies on different representations than actual grasping of real 3D objects. Yet the neural underpinnings of this phenomena have not been investigated. Here we used functional magnetic resonance imaging (fMRI) to investigate how brain activation patterns differed for grasping and reaching actions directed toward real 3D objects compared to images. Multivoxel Pattern Analysis (MVPA) revealed that the left anterior intraparietal sulcus (aIPS), a key region for visually guided grasping, discriminates between both the format in which objects were presented (real/image) and the motor task performed on them (grasping/reaching). Interestingly, during action planning, the representations of real 3D objects versus images differed more for grasping movements than reaching movements, likely because grasping real 3D objects involves fine-grained planning and anticipation of the consequences of a real interaction. Importantly, this dissociation was evident in the planning phase, before movement initiation, and was not found in any other regions, including motor and somatosensory cortices. This suggests that the dissociable representations in the left aIPS were not based on haptic, motor or proprioceptive feedback. Together, these findings provide novel evidence that actions, particularly grasping, are affected by the realness of the target objects during planning, perhaps because real targets require a more elaborate forward model based on visual cues to predict the consequences of real manipulation.

Distinct Visual Processing of Real Objects and Pictures of Those Objects in 7- to 9-month-old Infants.

The present study examined 7- and 9-month-old infants' visual habituation to real objects and pictures of the same objects and their preferences between real and pictorial versions of the same objects following habituation. Different hypotheses would predict that infants may habituate faster to pictures than real objects (based on proposed theoretical links between behavioral habituation in infants and neuroimaging adaptation in adults) or to real objects vs. pictures (based on past infant electrophysiology data). Sixty-one 7-month-old infants and fifty-nine 9-month-old infants were habituated to either a real object or a picture of the same object and afterward preference tested with the habituation object paired with either the novel real object or its picture counterpart. Infants of both age groups showed basic information-processing advantages for real objects. Specifically, during the initial presentations, 9-month-old infants looked longer at stimuli in both formats than the 7-month olds but more importantly both age groups looked longer at real objects than pictures, though with repeated presentations, they habituated faster for real objects such that at the end of habituation, they looked equally at both types of stimuli. Surprisingly, even after habituation, infants preferred to look at the real objects, regardless of whether they had habituated to photos or real objects. Our findings suggest that from as early as 7-months of age, infants show strong preferences for real objects, perhaps because real objects are visually richer and/or enable the potential for genuine interactions.

Real-world objects are more memorable than photographs of objects.

Research studies in psychology typically use two-dimensional (2D) images of objects as proxies for real-world three-dimensional (3D) stimuli. There are, however, a number of important differences between real objects and images that could influence cognition and behavior. Although human memory has been studied extensively, only a handful of studies have used real objects in the context of memory and virtually none have directly compared memory for real objects vs. their 2D counterparts. Here we examined whether or not episodic memory is influenced by the format in which objects are displayed. We conducted two experiments asking participants to freely recall, and to recognize, a set of 44 common household objects. Critically, the exemplars were displayed to observers in one of three viewing conditions: real-world objects, colored photographs, or black and white line drawings. Stimuli were closely matched across conditions for size, orientation, and illumination. Surprisingly, recall and recognition performance was significantly better for real objects compared to colored photographs or line drawings (for which memory performance was equivalent). We replicated this pattern in a second experiment comparing memory for real objects vs. color photos, when the stimuli were matched for viewing angle across conditions. Again, recall and recognition performance was significantly better for the real objects than matched color photos of the same items. Taken together, our data suggest that real objects are more memorable than pictorial stimuli. Our results highlight the importance of studying real-world object cognition and raise the potential for applied use in developing effective strategies for education, marketing, and further research on object-related cognition.