Perception of object shape and texture in human newborns: evidence from cross-modal transfer tasks

The present research investigates newborn infants' perceptions of the shape and texture of objects through studies of the bi-directionality of cross-modal transfer between vision and touch. Using an intersensory procedure, four experiments were performed in newborns to study their ability to transfer shape and texture information from vision to touch and from touch to vision. The results showed that cross-modal transfer of shape is not bi-directional at birth. Newborns visually recognized a shape previously held but they failed to tactually recognize a shape previously seen. In contrast, a bi-directional cross-modal transfer of texture was observed. Taken together, the results suggest that newborn infants, like older children and adults, gather information differently in the visual and tactile modes, for different object properties. The findings provide evidence for continuity in the development of mechanisms for perceiving object properties.     

Temporal order judgements as a sensitive measure of the spatial bias in patients with visuospatial neglect

Visuospatial neglect is not a unitary phenomenon, but can be better considered a syndrome, consisting of a multitude of different spatial and non‐spatial components. In this study, we used a temporal order judgement (TOJ) test in a large sample of stroke patients (n = 73) to scrutinize the contribution of a spatial bias to the performance on shape cancellation and line bisection tests. In the TOJ test, patients were presented with two elements, one in each visual field, after which the one needed to indicate which of the two elements was presented earlier. For each visual field, the presentation of the stimuli was determined by a staircase procedure where the interval between the two stimuli was determined by the performance of the patient. Results indicated that the strength of the spatial bias was strongly correlated with an object cancellation test, but not with a line bisection test. We argue that these findings are explained by differences in the extent to which a spatial bias determines performance on both tasks: In contrast to shape cancellation tests, successful performance on line bisection tests depends primarily on an object‐based, allocentric representation of space, unrelated to any spatial bias in the detection of elements in the contralesional visual field.     

三维图形的客体和空间工作记忆存储时程研究

研究采用单探测变化检测范式,探讨了三维图形在视觉客体和空间工作记忆中的存储时程。实验一的三维图形由不同颜色、形状组成,实验二的图形由不同颜色、图案组成。两个实验的结果均发现:被试的正确率随刺激间隔时间的延长而显著下降; 空间工作记忆任务的正确率显著高于客体工作记忆任务。研究结果表明,视觉刺激消失后,不论是客体信息还是空间信息,均随间隔时间的延长而逐渐衰退,且客体信息衰退的速度比空间信息快。总体来看,三维图形的客体和空间信息在视觉工作记忆满负荷条件下能保持大约3～5秒的时间。     

Recognition of complex object-centred spatial configurations in early infancy

In a series of experiments we tested 4- and 8-month-olds’ ability to represent the spatial layout of an object across changes in its orientation with respect to egocentric spatial coordinates. A fixed-trial familiarization procedure based on visual habituation behaviour shows that both age groups are able to discriminate between different object-centred spatial configurations. Furthermore, both age groups demonstrate the ability to make discriminations of object-centred spatial coordinates that require simultaneous reference to at least two spatial axes of the object. We discuss these findings in relation to theories of the early development of object recognition and spatial reference skills.     

PIGEONS ARE SENSITIVE TO THE SPATIAL ORGANIZATION OF COMPLEX VISUAL STIMULI

Abstract— Two experiments investigated the role of spatial organisation in the discrimination and generalization of complex visual stimuli by pigeons. In Experiment 1, after pigeons had been trained to discriminate line drawings of four objects, they were tested with novel pictures in which the same component parts of the objects were spatially rearranged. The spatially scrambled pictures led to a dramatic drop in recognition accuracy, hut responding remained above chance. In Experiment 2, pigeons reached a high level of discriminative performance when required to choose among four different spatial arrangements of the same object parts. These results confirm Cerella's (1980) conclusion that pigeons discriminate the component parts of complex visual stimuli, but. unless it is assumed that the scrambling deleted or created emergent features, the results disconfirm his conclusion that spatial organization plays no role in pigeons' picture perception.     

Haptic perception in newborns

Two experiments using different procedures were performed in which newborns’ ability to process information about object shape with their hands was explored. In the first experiment, a haptic fixed‐trial procedure was used and a decrease in holding times was found for both right and left hands. In the second experiment, discrimination between objects was studied in which a shifted procedure associated to an infant‐control procedure followed by a dishabituation procedure was used. Habituation to an object and a reaction to the novelty of a new object were shown for both right and left hands, showing that neonates are able to process and encode some information about object shape and then to discriminate between different shapes. It is the first evidence of such an ability in neonates. Methodological procedure and haptic cognition with regard to sensory symmetry are discussed and some developmental perspectives are proposed.     

Concurrent processing of spatial relations and objects in two cerebral hemispheres

This study examined hemispheric asymmetry for concurrent processing of object and spatial information. Participants viewed two successive stimuli, each of which consisted of two digits and two pictures that were randomly located and judged them as identical or different. A sample stimulus was presented in a central visual field, followed by a matching stimulus presented briefly in a left or right visual field. The matching stimuli were different from the sample stimuli with respect to the object (digit or picture) or spatial (locations or distances of items) aspect. No visual field asymmetry was found in the detection of object change. However, a left visual field advantage was found in the detection of spatial change. This result can be explained by the double filtering by frequency theory of Ivry and Robertson, who asserted that the left hemisphere has a bias for processing information contained in relatively high spatial frequencies whereas the right hemisphere has a bias for processing information contained in relatively low spatial frequencies. Based upon this evidence, the importance of interhemispheric integration for visual scene perception is discussed.     

Touching for knowing in infancy: The development of manual abilities in very young infants

This aim of this paper was twofold: (1) to display the various competencies of the infant's hands for processing information about the shape of objects; and (2) to show that the infant's haptic mode shares some common mechanisms with the visual mode. Several experiments on infants from birth and up to five months of age using a habituation/dishabituation procedure, intermodal transfer task between touch and vision, and various cognitive tasks revealed that infants may perceive and understand the physical world through their hands without visual control. From birth, infants can habituate to shape and detect discrepancies between shapes. But information exchanges between vision and touch are partial in cross-modal transfer tasks. Plausibly, modal specificities such as discrepancies in information gathering between the two modalities and the different functions of the hands (perceptual and instrumental) limit the links between the visual and haptic modes. In contrast, when infants abstract information from an event not totally felt or seen, amodal mechanisms underlie haptic and visual knowledge in early infancy. Despite various discrepancies between the sensory modes, conceiving the world is possible with hands as with eyes.     

The limits of newborn's grasping to detect texture in a cross-modal transfer task

Three experiments were conducted to investigate human newborns’ ability to perceive texture property tactually, either in a cross-modal transfer task or in an intra-modal tactual discrimination task. In Experiment 1, newborns failed to tactually recognize the texture (smooth vs. granular) of flat objects that they had previously seen, when they held flat objects. This failure was mainly due to a lack of intra-modal tactual discrimination between the two objects (Experiment 2). In contrast, Experiment 3 showed that newborns were able to tactually recognize the texture of previously seen surfaces when they held volumetric objects. Taken together, the results suggest that cross-modal transfer of texture from vision to touch stem from a peripheral mechanism, not a central mechanism. Grasping only allows newborns to perceive the texture of volumetric but not flat objects. As a consequence, this study reveals the limits of newborns’ grasping to detect and process information about texture. The results also suggest that more mature exploratory procedures, such as the “lateral motion” procedure exhibited by adults [Lederman, S. J., & Klatzky, R. (1987). Hand movements: A window into haptic object recognition. Cognitive Psychology, 19, 342–368], might be necessary for detecting the texture of flat objects in newborn infants.     

Le transfert intermodal des objets solides à leurs représentations graphiques chez les enfants : les capacités intermodales s’améliorent-elles avec l’âge ?

Children aged of four to six years participated in two cross-modal transfer tasks. (1) They were tactually familiarized with solid objects and then tested for visual recognition memory with outline drawings of them; (2) they were visually familiarized with drawings of objects and then tested for tactually recognition of solid objects. Six simple geometric shapes were presented to the children and could be named by them. Because a preliminary V-V transfer task was totally mastered by three to four year-old children, the children of this experiment were only subjected to an additional T-T transfer task with solid objects. This task permitted the investigation, in the course of development, of their ability to haptically recognize the correct familiar shape without seeing it. Correct recognitions were recorded. They increase similarly from four to five years in the three tasks. However, V-T cross-modal transfer was really mastered between five and six-years. These results are discussed in relation to the development of sensory modes and educational factors such as the learning of writing and reading in nursery school.     

Understanding the object benefit in visual short-term memory: the roles of feature proximity and connectedness

Past research has identified visual objects as the units of information processing in visual short-term memory (VSTM) and has shown that two features from the same object can be remembered in VSTM as well (or almost as well) as one feature of that object and are much better remembered than the same two features from two spatially separated objects. It is not clear, however, what drives this object benefit in VSTM. Is it the shared spatial location (proximity), the connectedness among features of an object, or both? In six change detection experiments, both location/proximity and connectedness were found to be crucial in determining the magnitude of the object benefit in VSTM. Together, these results indicate that location/proximity and connectedness are essential elements in defining a coherent visual object representation in VSTM.     

Integration of information from multiple element displays

This experiment examined the processing of information from multiple element visual displays, using techniques derived from the theory of signal detectability. The method allows one to specify how observers integrate information from individual elements of a display. The experiment tested numerical and graphical displays having different display sizes, durations, and arrangements of elements. Observer performance increased with the number, m, of display elements, but at less than the ideal √m rate. Observer performance was consistent with a model of information integration constrained by internal noise. Linear arrays of elements resulted in better performance than did square arrays. Graphically coded elements resulted in better performance than did numerical elements. Observer decision weighting of element information from graphical displays was approximately uniform across spatial position, but the weighting of information from numerical displays was concentrated on elements near the fixation point.     

Evidence of amodal representation of small numbers across visuo-tactile modalities in 5-month-old infants

Two experiments investigated 5-month-old infants’ amodal sensitivity to numerical correspondences between sets of objects presented in the tactile and visual modes. A classical cross-modal transfer task from touch to vision was adopted. Infants were first tactually familiarized with two or three different objects presented one by one in their right hand. Then, they were presented with visual displays containing two or three objects. Visual displays were presented successively (Experiment 1) or simultaneously (Experiment 2). In both experiments, results showed that infants looked longer at the visual display which contained a different number of objects from the tactile familiarization phase. Taken together, the results revealed that infants can detect numerical correspondences between a sequence of tactile and visual stimulation, and they strengthen the hypothesis of amodal and abstract representation of small numbers of objects (two or three) across sensory modalities in 5-month-old infants.     

Visual discrimination of delayed self-generated movement reveals the temporal limit of proprioceptive–visual intermodal integration

This study examined the intermodal integration of visual–proprioceptive feedback via a novel visual discrimination task of delayed self-generated movement. Participants performed a goal-oriented task in which visual feedback was available only via delayed videos displayed on two monitors—each with different delay durations. During task performance, delay duration was varied for one of the videos in the pair relative to a standard delay, which was held constant. Participants were required to identify and use the video with the lesser delay to perform the task. Visual discrimination of the lesser-delayed video was examined under four conditions in which the standard delay was increased for each condition. A temporal limit for proprioceptive–visual intermodal integration of 3–5 s was revealed by subjects’ inability to reliably discriminate video pairs.     

Bounding of letter sequences and the integration of visually presented words

Ss wrote down letters that were presented briefly in various temporal and geometric arrangements. Results reveal marked impairment in processing more than one temporally extended word in parallel. The impairment cannot be attributed to spatial separation of letters by itself, to sequence, or to inability to discriminate the letters. The concept of ‘bounding’ is introduced to account for the perception of familiar words in a continuing flow of information; the results suggest that only one object can be bounded at a time. They also suggest that the information that guides the eyes' movements in reading is qualitatively different from the information extracted from the printed text.     

The tactile perception of size: Some relationships with distance and direction

The results of a series of experiments carried out by Bartley (1953) demonstrated a tendency for the size of a tactually perceived object to be underestimated with increased distance of the object from the eyes. He took this to indicate that visual imagery played a part in the spatial organization of tactile data. In the present investigation this effect of distance was further examined under various conditions with sighted and blind subjects. The tendency was found to exist, but there is clear evidence that it is not due to the participation of visual imagery. No hypothesis was found to explain the tendency adequately. An interesting difference emerges between the situation where the subject extends his arm when making the comparison and that in which the arm is retracted when making the comparison.     

A computational framework for attentional object discovery in RGB-D videos

We present a computational framework for attention-guided visual scene exploration in sequences of RGB-D data. For this, we propose a visual object candidate generation method to produce object hypotheses about the objects in the scene. An attention system is used to prioritise the processing of visual information by (1) localising candidate objects, and (2) integrating an inhibition of return (IOR) mechanism grounded in spatial coordinates. This spatial IOR mechanism naturally copes with camera motions and inhibits objects that have already been the target of attention. Our approach provides object candidates which can be processed by higher cognitive modules such as object recognition. Since objects are basic elements for many higher level tasks, our architecture can be used as a first layer in any cognitive system that aims at interpreting a stream of images. We show in the evaluation how our framework finds most of the objects in challenging real-world scenes.     

Parallel perceptual/cognitive functions in humans and rats: space and time

The nature of the evidence on the role played by early stimulation history in perceptual development related to an appreciation of intermodal attributes involving space and time is reviewed. In conjunction with this analysis, an examination was undertaken of the effect of early visual deprivation on the ability of dark- (DR) and light-reared (LR) rats to learn discriminations involving location of sounds or lights and to abstract the intersensory correspondence involved from the initial modality-specific training. Visually inexperienced DR rats were somewhat slower to acquire a discrimination involving the location of visual events under some stimulus/response arrangements. More importantly, such animals were not as effective as their visually experienced LR counterparts in demonstrating cross-modal transfer (CMT) to signals in a new modality. The present study also revealed that CMT involving location of signals was less salient than CMT of duration information in rats regardless of their rearing condition. Finally, findings are discussed more generally, providing contextual information that bears on issues related to parallel cognitive functions in rats and human neonates and on the role of early visual experience in the ontogeny of intersensory perceptual competence in mammals.