Arlette Streri

Representations of space, time, and number in neonates

Significance Space, time, and number are connected in the world and in the human mind. How do these connections arise? Do we learn to link larger numbers and durations to longer spatial extents because they are correlated in the world, or is the human mind built to capture these relations? We showed that neonates relate both number and duration to spatial length when these dimensions vary in the same direction (number or duration increases as length increases), but not in opposite directions (number or duration increases and length decreases). After being familiarized to a pairing between two magnitudes, newborns expect these dimensions to change in the same direction. At birth, humans are sensitive to the common structure of these fundamental magnitudes. A rich concept of magnitude—in its numerical, spatial, and temporal forms—is a central foundation of mathematics, science, and technology, but the origins and developmental relations among the abstract concepts of number, space, and time are debated. Are the representations of these dimensions and their links tuned by extensive experience, or are they readily available from birth? Here, we show that, at the beginning of postnatal life, 0- to 3-d-old neonates reacted to a simultaneous increase (or decrease) in spatial extent and in duration or numerical quantity, but they did not react when the magnitudes varied in opposite directions. The findings provide evidence that representations of space, time, and number are systematically interrelated at the start of postnatal life, before acquisition of language and cultural metaphors, and before extensive experience with the natural correlations between these dimensions.

Cross-modal recognition of shape from hand to eyes in human newborns.

The hypothesis that the ability to coordinate information between tactual and visual modalities is present at birth and dependent on perceptual inherent structures was tested in human newborns. Using an intersensory paired-preference procedure, we showed that newborns can visually recognize the shape of an object that they have previously manipulated with their right hand, out of sight. This is an experimental evidence that newborns can extract shape information in a tactual format and transform it in a visual format before they have had the opportunity to learn from the pairings of visual and tactual experience. This is contrary to a host of theories and models of perceptual learning, both traditional (empiricist philosophers) and modern (connectionist).

Haptic perception of objects in infancy.

Abstract Four-month-old infants held two rings, one in each hand, out of the field of view. In one condition, the rings could be moved independently; in the other condition, the rings could only be moved rigidly together. After exploring the rings haptically, infants received a haptic or visual test with pairs of rings that were connected or separated. The findings of four experiments provide evidence that infants explored the rings bimanually, producing patterns of rigid or independent motion, that infants discriminated between the two motion patterns, and that this discrimination transferred from touch to vision. Most importantly, the experiments provide evidence that infants perceived the unity and boundaries of objects by detecting the motion patterns they themselves produced. Infants who explored the independently movable rings perceived two distinct objects, whereas those who explored the rigidly movable rings perceived a single object that was connected between the two hands. Since the same motion patterns specify object boundaries in the visual mode, object perception may depend on a relatively central process.

Cross-modal recognition of shape from hand to eyes and handedness in human newborns.

The present research addresses the question of the generality of the ability to transfer shape information from one hand to the eyes recently evidenced in human newborns. Using an intersensory paired-preference procedure, we confirmed that newborns can visually recognize the shape of an object that they have previously manipulated with their right hand, out of sight. However, the results revealed that this ability is absent when the left hand is involved. Handedness in cross-modal transfer task is discussed in relation to other behavioral asymmetries in newborns. Taken together, the present research confirms the existence in some conditions of an early fragile ability to extract shape information in a tactual format and transfer it to a visual format, independent of common experience.

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.

Tactual habituation and discrimination of form in infancy: A comparison with vision.

Tactual discriminative abilities out of the control of vision are studied in 5-month-old infants, and compared with their visual discriminative abilities. The relevance of a habituation/reaction to novelty procedure in the tactual modality is tested. An infant control procedure is used in both modalities on 2 independent samples of 32 infants each. Habituation and discrimination occur tactually as well as visually, the duration of holds decreasing more than the duration of looks. Accumulated holding time is 3 times longer than accumulated looking time. Analogies and discrepancies between tactual and visual habituations are discussed, and the problem of sensory dominance is raised. Such results are basic to studies on cross-modal transfer, from vision to touch as well as from touch to vision.

Recognition of unfamiliar talking faces at birth

Sai (2005) investigated the role of speech in newborns’ recognition of their mothers’ faces. Her results revealed that, when presented with both their mother’s face and that of a stranger, newborns preferred looking at their mother only if she had previously talked to them. The present study attempted to extend these findings to any other faces. By using video films, our results revealed that unfamiliar female faces were recognized in the test phase only if they had previously talked to the baby, but not if they had been silent. These results highlight the importance of an early audiovisual perception which already seems to play an important role in face processing at birth.

Dissociation between small and large numerosities in newborn infants

In the first year of life, infants possess two cognitive systems encoding numerical information: one for processing the numerosity of sets of 4 or more items, and the second for tracking up to 3 objects in parallel. While a previous study showed the former system to be already present a few hours after birth, it is unknown whether the latter system is functional at this age. Here, we adapt the auditory-visual matching paradigm that previously revealed sensitivity to large numerosities to test sensitivity to numerosities spanning the range from 2 to 12. Across studies, newborns discriminated pairs of large numerosities in a 3:1 ratio, even when the smaller numerosity was 3 (3 vs. 9). In contrast, newborn infants failed to discriminate pairs including the numerosity 2, even at the same ratio (2 vs. 6). These findings mirror the dissociation that has been reported with older infants, albeit with a discontinuity situated between numerosities 2 and 3. Two alternative explanations are compatible with our results: either newborn infants have a separate system for processing small sets, and the capacity of this system is limited to 2 objects; or newborn infants possess only one system to represent numerosities, and this system either is not functional or is extremely imprecise when it is applied to small numerosities.

Cues for early social skills: direct gaze modulates newborns' recognition of talking faces.

Previous studies showed that, from birth, speech and eye gaze are two important cues in guiding early face processing and social cognition. These studies tested the role of each cue independently; however, infants normally perceive speech and eye gaze together. Using a familiarization-test procedure, we first familiarized newborn infants (n = 24) with videos of unfamiliar talking faces with either direct gaze or averted gaze. Newborns were then tested with photographs of the previously seen face and of a new one. The newborns looked longer at the face that previously talked to them, but only in the direct gaze condition. These results highlight the importance of both speech and eye gaze as socio-communicative cues by which infants identify others. They suggest that gaze and infant-directed speech, experienced together, are powerful cues for the development of early social skills.

Visual-tactual and tactual-visual transfer between objects and pictures in 2-month-old infants

Previous studies have provided evidence for transfer of perception of object shape from touch to vision, but not from vision to touch, in young infants. Previous studies also indicate that intermodal recognition can produce a preference either for a matching or for a nonmatching object. We investigated the causes of asymmetries in intermodal transfer and of familiarity preference versus novelty preference in transfer tasks. The data support three conclusions: (i) Transfer from vision to touch is possible under certain conditions and is facilitated by the use of two-dimensional (2-D) visual representations rather than three-dimensional (3-D) visual objects, (ii) The direction of preferences in a transfer task depends on the degree of dissimilarity between the haptically and visually presented objects. Familiarity preferences increase with increasing difference between the object to be recognised and the familiar object, (iii) Infants are able to perceive the 3-D shape of an object both visually and haptically, and they are sensitive both to commonalities and to discrepancies between the shapes of 3-D objects and of their 2-D representations. Hierarchical levels of perceptual processing are proposed to account for these findings.