Haptic perception of material properties by 3-month-old infants

Prior visual experience increases children's use of effective haptic exploration strategies in audio-tactile sound-shape correspondences

Sound-shape correspondence refers to the preferential mapping of information across the senses, such as associating a nonsense word like bouba with rounded abstract shapes and kiki with spiky abstract shapes. Here we focused on audio-tactile (AT) sound-shape correspondences between nonsense words and abstract shapes that are felt but not seen. Despite previous research indicating a role for visual experience in establishing AT associations, it remains unclear how visual experience facilitates AT correspondences. Here we investigated one hypothesis: seeing the abstract shapes improve haptic exploration by (a) increasing effective haptic strategies and/or (b) decreasing ineffective haptic strategies. We analyzed five haptic strategies in video-recordings of 6- to 8-year-old children obtained in a previous study. We found the dominant strategy used to explore shapes differed based on visual experience. Effective strategies, which provide information about shape, were dominant in participants with prior visual experience, whereas ineffective strategies, which do not provide information about shape, were dominant in participants without prior visual experience. With prior visual experience, poking-an effective and efficient strategy-was dominant, whereas without prior visual experience, uncategorizable and ineffective strategies were dominant. These findings suggest that prior visual experience of abstract shapes in 6- to 8-year-olds can increase the effectiveness and efficiency of haptic exploration, potentially explaining why prior visual experience can increase the strength of AT sound-shape correspondences.

Visuo-haptic processing of unfamiliar shapes: Comparing children and adults

The question of how our sensory perception abilities develop has been an active area of research, establishing trajectories of development from infancy that last well into late childhood and even adolescence. In this context, several studies have established changes in sensory processing of vision and touch around the age of 8 to 9 years. In this experiment, we explored the visual and haptic perceptual development of elementary school children of ages 6-11 in similarity-rating tasks of unfamiliar objects and compared their performance to adults. The participants were presented with parametrically-defined objects to be explored haptically and visually in separate groups for both children and adults. Our results showed that the raw similarity ratings of the children had more variability compared to adults. A detailed multidimensional scaling analysis revealed that the reconstructed perceptual space of the adult haptic group was significantly closer to the parameter space compared to the children group, whereas both groups' visual perceptual space was similarly well reconstructed. Beyond this, however, we found no clear evidence for an age effect in either modality within the children group. These results suggest that haptic processing of unfamiliar, abstract shapes may continue to develop beyond the age of 11 years later into adolescence.

Not only motor skill performance but also haptic function is impaired in children with developmental language disorder

BACKGROUND

Previous studies have found an association between motor immaturity and developmental language impairment in children. However, systematic investigations of somatosensory dysfunctions that might be linked to motor deficits in children with developmental language disorder (DLD) are lacking.

AIMS

Examined haptic perception and motor skills in school-age children with DLD and typically-developing (TD) children.

METHODS

Sixteen children with DLD and sixteen age-matched TD children performed a curvature detection task measuring haptic sensitivity and a curvature discrimination task measuring haptic acuity. The Movement Assessment Battery for Children, 2nd edition (MABC-2) was also conducted to evaluate children's motor ability.

RESULTS

The results revealed elevated thresholds of both haptic detection (67.5%) and haptic discrimination (67.9%) in the DLD group when compared to the TD group. In addition, the children with DLD performed significantly less well on the manual dexterity of MABC-2. Finally, a lower haptic acuity was associated with poorer manual dexterity scores of MABC-2.

CONCLUSIONS

This study demonstrates for the first time that not only motor skills, but also haptic function is altered in children with DLD. The observed association between manual dexterity and haptic acuity suggests a close relationship between haptic and motor skills in school-age children.

Training of 7-month-old infants' manual object exploration skills: Effects of active and observational experience

In the present study, a fine motor training was developed and evaluated in which infants were trained to manually explore objects in an advanced manner. Fifty 7-month-old infants were randomly assigned to three different training conditions: (1) to an active manual exploration training, in which they learned to explore objects efficiently, (2) to an observational manual exploration training, in which they observed how an adult performed sophisticated actions on objects, or (3) to a control group receiving no training. The results impressively indicate that infants with a low level of object exploration skill prior to the training showed the most training effects as compared to infants with proficient object exploratory actions. Interestingly, this differential training effect was true for both the active and observational training, highlighting the role of social learning in infancy. Importantly, our study shows for the first time the impact of normal individual variation in infants' manual object exploration skills on the effects of a fine motor training.

Fragility of haptic memory in human full-term newborns

BACKGROUND

Numerous studies have established that newborns can memorize tactile information about the specific features of an object with their hands and detect differences with another object. However, the robustness of haptic memory abilities has already been examined in preterm newborns and in full-term infants, but not yet in full-term newborns. This research is aimed to better understand the robustness of haptic memory abilities at birth by examining the effects of a change in the objects' temperature and haptic interference.

METHODS

Sixty-eight full-term newborns (mean postnatal age: 2.5 days) were included. The two experiments were conducted in three phases: habituation (repeated presentation of the same object, a prism or cylinder in the newborn's hand), discrimination (presentation of a novel object), and recognition (presentation of the familiar object). In Experiment 1, the change in the objects' temperature was controlled during the three phases.

RESULTS AND CONCLUSION

Results reveal that newborns can memorize specific features that differentiate prism and cylinder shapes by touch, and discriminate between them, but surprisingly they did not show evidence of recognizing them after interference. As no significant effect of the temperature condition was observed in habituation, discrimination and recognition abilities, these findings suggest that discrimination abilities in newborns may be determined by the detection of shape differences. Overall, it seems that the ontogenesis of haptic recognition memory is not linear. The developmental schedule is likely crucial for haptic development between 34 and 40 GW.

Depressed and non-depressed mothers' touching during social interactions with their infants

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Depressed mothers engage in less touching that is playful and interactive in nature.

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Depressed mothers touch their infants less during face-to-face interactions.

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Nondepressed mothers maintain high levels of touch following a perturbation period.

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Depressed mothers decrease playful/stimulating touch after a perturbation period.

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Implications for intervention programs of early touch stimulation for at-risk dyads.

Touch is a critical channel of communication used by mothers to communicate and interact with their infants and to contribute to their infants’ socio-emotional development. The present study examined maternal touching in 41 mothers with and without depressive symptomatology. Mothers and their 4-month-old infants participated in the Still-Face (maternal emotional unavailability) and Separation (maternal physical unavailability) procedures. Maternal touching behaviours were video-recorded and coded using the Caregiver Infant Touch Scale (CITS). Results indicated that mothers with higher levels of depressive symptoms engaged in less touching following the perturbation period in the Still-Face procedure, whereas mothers with lower levels of depressive symptoms maintained stable levels of touching across both interaction periods. Mothers with higher levels of depressive symptoms displayed less playful/stimulating types of touching. Taken together, these results underscore the importance of touch and suggest key differences in touching behaviour between dyads with maternal depressive symptomatology and those without.

Sound effects: Multimodal input helps infants find displaced objects

Before 9 months, infants use sound to retrieve a stationary object hidden by darkness but not one hidden by occlusion, suggesting auditory input is more salient in the absence of visual input. This article addresses how audiovisual input affects 10-month-olds' search for displaced objects. In AB tasks, infants who previously retrieved an object at A subsequently fail to find it after it is displaced to B, especially following a delay between hiding and retrieval. Experiment 1 manipulated auditory input by keeping the hidden object audible versus silent, and visual input by presenting the delay in the light versus dark. Infants succeeded more at B with audible than silent objects and, unexpectedly, more after delays in the light than dark. Experiment 2 presented both the delay and search phases in darkness. The unexpected light-dark difference disappeared. Across experiments, the presence of auditory input helped infants find displaced objects, whereas the absence of visual input did not. Sound might help by strengthening object representation, reducing memory load, or focusing attention. This work provides new evidence on when bimodal input aids object processing, corroborates claims that audiovisual processing improves over the first year of life, and contributes to multisensory approaches to studying cognition. Statement of contribution What is already known on this subject Before 9 months, infants use sound to retrieve a stationary object hidden by darkness but not one hidden by occlusion. This suggests they find auditory input more salient in the absence of visual input in simple search tasks. After 9 months, infants' object processing appears more sensitive to multimodal (e.g., audiovisual) input. What does this study add? This study tested how audiovisual input affects 10-month-olds' search for an object displaced in an AB task. Sound helped infants find displaced objects in both the presence and absence of visual input. Object processing becomes more sensitive to bimodal input as multisensory functions develop across the first year.

Sticky mittens, prickly Velcro, and infants' transition into independent reaching: Response to Williams, Corbetta, and Guan (2015)

Williams, Corbetta, and Guan (2015) report findings on the effects of active and passive motor training in three-month-old infants and argue that passive task exposure is sufficient to encourage future reaching behaviors. In this commentary, we relate these new findings to our body of published work using sticky mittens and describe important differences in the materials and procedures used. In particular, Williams et al. (2015) used modified sticky mittens that allowed infants' fingers to make direct contact with prickly Velcro on the toys, and they used a different training procedure that required infants to discover the hidden functionality of the sticky mittens by themselves. We argue that these differences explain the apparent conflicts between our prior work and the results reported by Williams et al. (2015). The Williams study presented infants with a learning context that was quite different from the one infants encountered in our research, and so it is not surprising that infants in their study showed such different patterns of behavior.

Three Lessons Learned

In this article, I describe varied observations from the past 60 years that motivated three significant changes in the assumptions I held as a young psychologist interested in the development of children. Aspects of these early assumptions penetrate a great deal of current research. The new beliefs are (a) a greater willingness to base concepts on patterns of measurements rather than single independent or dependent variables, (b) learning to include the physical features of the observational setting, including the procedure that generated the evidence, as well as the participants' gender, social class, and cultural background, as part of the concept, and (c) remaining aware of the possibility that the relations among continuous variables can change as a function of brain maturation during the early stages of childhood.

Physically developed and exploratory young infants contribute to their own long-term academic achievement

A developmental cascade defines a longitudinal relation in which one psychological characteristic uniquely affects another psychological characteristic later in time, separately from other intrapersonal and extrapersonal factors. Here, we report results of a large-scale (N = 374), normative, prospective, 14-year longitudinal, multivariate, multisource, controlled study of a developmental cascade from infant motor-exploratory competence at 5 months to adolescent academic achievement at 14 years, through conceptually related and age-appropriate measures of psychometric intelligence at 4 and 10 years and academic achievement at 10 years. This developmental cascade applied equally to girls and boys and was independent of children's behavioral adjustment and social competence; mothers' supportive caregiving, verbal intelligence, education, and parenting knowledge; and the material home environment. Infants who were more motorically mature and who explored more actively at 5 months of age achieved higher academic levels as 14-year-olds.

Disappearing Décalage: Object Search in Light and Dark at 6 Months

Infants search for an object hidden by an occluder in the light months later than one hidden by darkness. One explanation attributes this décalage to easier action demands in darkness versus occlusion, whereas another attributes it to easier representation demands in darkness versus occlusion. However, search tasks typically confound these two types of demands. This article presents a search task that unconfounds them to better address these two explanations of the "dark advantage." Objects were hidden by submersion in liquid instead of occlusion with a screen, allowing infants to search with equally simple actions in light versus dark. In Experiment 1, 6-month-olds unexpectedly showed a dark disadvantage by discriminating when an object was hidden in the light but not the dark. Experiment 2 addressed the possibility that representation demands were higher in the dark than the light and showed that infants' search in the dark increased to match that in the light, but not exceed it. Six-month-olds can thus search for a hidden object both when action demands are simplified and when a noncohesive substance rather than a cohesive occluder hides the object, supporting aspects of both action-demand and representation-demand explanations of décalage in search behavior.

Manual exploration of consistency (soft vs hard) and handedness in infants from 4 to 6 months old

In infants the developmental course of haptic perception is constrained by the development of attention to object properties and of the ability to execute various movements with the hands. The purpose of this study is to consider how infants, aged 4 to 6 months, become able to use their hands to assess qualities of objects such as consistency (softness vs hardness). The object that the infants explored was a cylinder, divided into four equal parts that were alternately hard and soft. It was tactually heterogeneous but visually homogeneous. Two aspects of exploration according to age, hand used, and consistency touched were considered: (1) the mode of exploration, contact, pressure, and tapping; and (2) the means of exploration, whole hand or fingers. The results show that infants adjust their movements to the quality of the object they are testing. That is, the infant varies the distribution of investigative and manipulative behaviours according to the nature of the specific object being explored. Pressure movements were the predominant exploratory procedures used for the soft parts, whereas passive contacts were the predominant movements for the hard parts. Concerning manual laterality, the results show that the left hand is used for touching objects (passive contact) more than the right one, whereas the right hand is used to press the soft parts and tap the hard parts more than the left hand.

Exploring objects with feet advances movement in infants born preterm: a randomized controlled trial

BACKGROUND

Previous work has shown that full-term infants who were healthy contacted a toy with their feet several weeks before they did so with their hands and that movement training advanced feet reaching. Certain populations of preterm infants are delayed in hand reaching; however, feet reaching has not been investigated in any preterm population.

OBJECTIVE

The primary purpose of this study was to determine whether preterm infants born at less than 33 weeks of gestational age contacted a toy with their feet at 2 months of corrected age, before doing so with their hands, and whether movement training advanced feet reaching.

DESIGN

This study was a randomized controlled trial.

METHODS

Twenty-six infants born preterm were randomly assigned to receive daily movement training or daily social training. During the 8-week training period, the infants were videotaped in a testing session every other week from 2 to 4 months of age.

RESULTS

Both groups contacted the toy with their feet at 2 months of age during the first testing session prior to training, at an age when no infants consistently contacted the toy with their hands. After 8 weeks of training, the movement training group displayed a greater number and longer duration of foot-toy contacts compared with the social training group.

CONCLUSIONS

These results suggest that movement experiences advance feet reaching as they do for hand reaching. For clinicians, feet-oriented play may provide an early intervention strategy to encourage object interaction for movement impairments within the first months of postnatal life. Future studies can build on these results to test the long-term benefit of encouraging early purposeful leg movements.

Relation of stable hand-use preferences to the development of skill for managing multiple objects from 7 to 13 months of age

Expression of multiple object management skills (manual acquisition and storage of objects) was examined longitudinally at 7, 9, 11, and 13 months for 38 infants (19 females) whose hand use preference was either stable (consistently right or left across the ages) or nonstable (either no hand-use preference exhibited or inconsistent preference across the ages). Four separate sets of four distinctive objects each were presented singly to the infant's right and left side, with the presentation of each subsequent object contingent on the infant manipulating the previous object. Expression of multiple object management skills significantly increased with age. Infants with stable hand-use preferences produced more object acquisition and storage acts than those without a stable hand-use preference. Older infants with stable hand-use preferences exhibited more "sophisticated" sequences of multiple object management acts than those without. The role of stable hand-use preference in the development of manual skill and cognition is discussed.

WEIGHT PERCEPTION IN NEONATE INFANTS

A recent research revealed the capacity of the newborn to haptically detect, the weight of an object [12]. In this research, we tried to determine the means by which newborn infants, not having yet exploratory procedures, are able to treat this object property. We support the assumption that tactile perceptive capacities of the newborn infants derive from a fundamental property of the sensorimotor system: its primary variability. After a period of habituation with a heavy or light object, an object of new weight is presented (period test). Three parameters of the sensorimotor activity were analyzed during these two periods: holding times, amplitude of the pressure exerted on the object and frequency of the pressure. Analyses of these parameters demonstrate the neonate's capacity to discriminate objects weight.