Active touch in late-preterm and early-term neonates.

An infant-controlled tactile habituation without visual control procedure was used to evaluate the ability of 32 late-preterm neonates (mean gestational age: 34 weeks) and 32 early-term neonates (mean gestational age: 38 weeks) to actively explore with hands objects varying in texture (smooth, granular). Holding time and Hand Pressure Frequency (HPF) were recorded. Holding time decreased as habituation progressed in both group of neonates. Holding time increased from habituation trials to test trials only in early-term neonates. A reaction to novelty was only observed in early-term neonates. During habituation, HPF remained unchanged in late-preterm infants whereas HPF decreased in early-term infants. HPF increased from habituation trials to test trials in early-term neonates and in late-preterm infants. However, reaction to novelty was only observed for early-term infants. The significance of these results is discussed in reference to brain maturation in preterm infants.

Haptic processing in newborns of depressed and nondepressed mothers.

This study was conducted to compare how newborns of depressed mothers and newborns of nondepressed mothers gather tactile information about texture. Spontaneous manual activity on objects with a smooth or rough texture was recorded in 20 newborns born of mothers with a high risk of depression or a low risk of depression. An important result of the present study is that texture-based modulation of hand-pressing frequency was observed in both neonates born of depressed mothers and neonates born of nondepressed mothers. Moreover, hand-pressing frequency did not depend on the pressure exerted on the object, since all neonates displayed comparable pressure on the held object. Lastly, the results revealed that newborns of depressed mothers held the rough object twice as long as newborns of nondepressed mothers. These results are analyzed in reference to deregulated biochemical functions in neonates born of mothers with a high risk of depression.

Newborn infants perceive abstract numbers.

Although infants and animals respond to the approximate number of elements in visual, auditory, and tactile arrays, only human children and adults have been shown to possess abstract numerical representations that apply to entities of all kinds (e.g., 7 samurai, seas, or sins). Do abstract numerical concepts depend on language or culture, or do they form a part of humans' innate, core knowledge? Here we show that newborn infants spontaneously associate stationary, visual-spatial arrays of 4-18 objects with auditory sequences of events on the basis of number. Their performance provides evidence for abstract numerical representations at the start of postnatal experience.

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.

Inter-manual transfer of object texture and shape in human neonates.

Two experiments, using habituation/reaction to novelty procedure, were performed to assess human neonates' ability to process and exchange information about texture (Experiment 1) or shape (Experiment 2) between their hands, without visual control. Forty-eight newborn infants (24 per experiment) received a haptic habituation either with their right or left hand followed by a haptic discrimination test in the opposite hand. Results revealed two patterns of behaviour, according to the object property to be processed. After a tactual habituation to a texture in one hand, newborns held the novel texture longer in the other hand. On the contrary, after a tactual habituation to a shape in one hand, the familiar shape was held longer in the opposite hand. The findings suggest that inter-manual transfer is possible at birth despite of the relative immaturity of the corpus callosum. The discrepancies of performances between object properties are discussed in relation to the possibility of a different haptic processing of texture and shape in the newborn brain.

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.