Tactual perception: a review of experimental variables and procedures <s> Children <s> The robustness of infant haptic memory was assessed in terms of its capacity to withstand either a brief delay or potential retroactive “interference” from other haptic input. 48 infants (mean age 8 months) were familiarized haptically to a small cube or sphere with smooth or rough surface texture and subsequently tested for recognition of the shape and texture of this stimulus in terms of the relative level of haptic response to 3 test stimuli, comprising the familiar stimulus, a new-shape stimulus, and a new-texture stimulus. The test stimuli were presented (a) immediately, (b) after a 5-min delay, or (c) after a second familiarization or “interference” phase involving another haptic stimulus different in shape and texture to the first. The infants demonstrated recognition of shape and texture in the No Delay condition, of shape and (marginally) of texture in the Delay condition, but only of texture in the Interference condition. The greater susceptibility of shape to interference was considered in terms of the degree of similarity among the shapes employed in the study. <s> BIB001 </s> Tactual perception: a review of experimental variables and procedures <s> Children <s> 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. <s> BIB002 </s> Tactual perception: a review of experimental variables and procedures <s> Children <s> Five-year-old children explored multidimensional objects either haptically or visually and then were tested for recognition with target and distractor items in either the same or the alternative modality. In Experiments 1 and 2, haptic, visual, and cross-modal recognition were all nearly with familiar objects; haptic and visual recognition were also excellent with unfamiliar objects, but cross-modal recognition was less accurate. In Experiment 3, cross-modal recognition was also less accurate than within-mode recognition with familiar objects that were members of the same basic-level category. The results indicate that children's haptic recognition is remarkably good, that cross-modal recognition is otherwise constrained, and that cross-modal recognition may be accomplished differently for familiar and unfamiliar objects. <s> BIB003 </s> Tactual perception: a review of experimental variables and procedures <s> Children <s> Tactile memory systems are involved in the storage and retrieval of information about stimuli that impinge on the body surface and objects that people explore haptically. Here, the authors review the behavioral, neuropsychological, neurophysiological, and neuroimaging research on tactile memory. This body of research reveals that tactile memory can be subdivided into a number of functionally distinct neurocognitive subsystems, just as is the case with auditory and visual memory. Some of these subsystems are peripheral and short lasting and others are more central and long lasting. The authors highlight evidence showing that the representation of tactile information interacts with information about other sensory attributes (e.g., visual, auditory, and kinaesthetic) of objects/events that people perceive. This fact suggests that at least part of the neural network involved in the memory for touch might be shared among different sensory modalities. In particular, multisensory/amodal information-processing networks seem to play a leading role in the storage of tactile information in the brain. <s> BIB004 </s> Tactual perception: a review of experimental variables and procedures <s> Children <s> Abstract Researchers agree that infants must learn from prior sensory-motor experiences to plan, perform, and fine-tune their actions to the environment. Yet, little is known about the actual influences of these experiences on the development of infants’ perception and action. This study investigated how repeated experiences of seeing, reaching for, touching, grasping, and manipulating objects of same sizes and textures contributed to the refinement of subsequent object-oriented motor responses in 6–9-month old infants. In addition, to understand whether infants relied on vision, touch, or both to tailor their motor response to objects, we analyzed the reach-to-grasp sequences. Results show that the youngest infants did not benefit from the repeated experiences. Seemingly stereotypical motor responses appeared to interfere with the process of perceptual-motor mapping. The older infants relied more effectively on prior experience, on touch initially and then vision, to match their motor responses to objects. Consistent with a dynamic systems approach, we interpret the observed developmental progression as a change in tensions between perception and action. <s> BIB005
Developmental approach to touch is interesting to understand how human perception evolves through life span and can also provide some insight into how information acquired by touch is processed and weighted at different ages. Studies with very young children (before the development of language) are relevant because they allow access to truly perceptual tactile features, since young children are not capable of semantically or verbally encode or rehearse the stimuli BIB004 . There are some studies regarding touch in newborns and infants, mainly recurring to the novelty paradigm. This paradigm is based on the conclusion that babies tend to be attracted by new stimuli and was designed on the assumption that the time a child spends exploring a stimulus provides a measure of its novelty. Longer exploration times indicate the stimulus is being perceived as new. With the novelty paradigm, the existence of some form of tactile memory has been reported in children as young as two months old  , and even newborns were capable of detecting changes in two stimuli with either hand BIB002 . Also, BIB001 , in a study with infants with about eight months of age, showed retention of tactile information for both shape and texture with immediate recognition, for shape and to lesser extent texture after a delay and only for texture in interference conditions. BIB005 highlighted the role of touch in early development, considering that coordination between touch and vision is crucial to maintain an interaction with the surrounding stimuli, and trying to analyse the relative weight of tactile and visual experience in the modulation of grasping, reaching and other objectoriented motor responses of six-to nine-month-old children. Results showed that younger children did not adapt their movements according to previous experience with the stimuli, but older children did, relying first on touch information and later more in visual cues to match their movements to the specific objects, based on previous experience with them BIB005 .  reported a study with two groups of children, one with children around two and a half years old and the other with children of 5 years old and asked them to haptically identify miniatures of small objects (e.g., doll's spoon), miniatures of large objects (e.g., doll's sofa) and small objects in real size (e.g., key). Older children were better than younger children in all conditions, and both groups were better at identifying small objects in real size than either of the two other object sets. Curiously, the younger children were able to identify more small miniaturised objects than large miniaturised objects, a pattern that was not observed in older children. The author concluded that younger children had more difficulty in haptically perceiving and exploring objects they cannot compare in real size, and the greater difficulty in identifying the miniatures of large objects was a consequence of lack of experience of haptic exploration of the objects in real life. As for the older children, their crossmodal abilities were more developed, and they were able to identify the objects by translating the visual information from real life to haptic information. BIB003 in a recognition study with familiar (e.g., toothbrush) and unfamiliar (e.g., feather boa) objects with a group of 5-year-old children reported a ''remarkably good'' haptic memory, nearly perfect for familiar objects and excellent for unfamiliar objects as well. The exploratory procedures of children up to 11 years old did not seem to be strictly object-or property-dependent  , with children performing the same movements, independently of the given instruction, while adults adjusted the exploratory procedures both to object and to task specificity. Haptic perception relies highly on movements and intentional exploration, and as such is dependent on the development of the motor system; likewise, the development of cognitive abilities like working memory is important to adjust, maintain and bind acquired information that allows haptic perception and motor optimisation of the manipulation procedures  . Children show the ability to retain haptic specific information from birth and seem to initially use mainly motor and haptic features to guide objects' exploration. However, the accuracy in haptic recognition of unfamiliar items and the ability to adjust exploration procedures seem to develop later.