Learning to reach with “sticky” or “non-sticky” mittens: A tale of developmental trajectories

Early developmental intervention programmes provided post hospital discharge to prevent motor and cognitive impairment in preterm infants

BACKGROUND

Infants born preterm are at increased risk of cognitive and motor impairments compared with infants born at term. Early developmental interventions for preterm infants are targeted at the infant or the parent-infant relationship, or both, and may focus on different aspects of early development. They aim to improve developmental outcomes for these infants, but the long-term benefits remain unclear. This is an update of a Cochrane review first published in 2007 and updated in 2012 and 2015.

OBJECTIVES

Primary objective To assess the effect of early developmental interventions compared with standard care in prevention of motor or cognitive impairment for preterm infants in infancy (zero to < three years), preschool age (three to < five years), and school age (five to < 18 years). Secondary objective To assess the effect of early developmental interventions compared with standard care on motor or cognitive impairment for subgroups of preterm infants, including groups based on gestational age, birthweight, brain injury, timing or focus of intervention and study quality.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, PsycINFO and trial registries in July 2023. We cross-referenced relevant literature, including identified trials and existing review articles.

SELECTION CRITERIA

Studies included randomised, quasi-randomised controlled trials (RCTs) or cluster-randomised trials of early developmental intervention programmes that began within the first 12 months of life for infants born before 37 weeks' gestational age (GA). Interventions could commence as an inpatient but had to include a post discharge component for inclusion in this review. Outcome measures were not prespecified, other than that they had to assess cognitive outcomes, motor outcomes or both. The control groups in the studies could receive standard care that would normally be provided.

DATA COLLECTION AND ANALYSIS

Data were extracted from the included studies regarding study and participant characteristics, timing and focus of interventions and cognitive and motor outcomes. Meta-analysis using RevMan was carried out to determine the effects of early developmental interventions at each age range: infancy (zero to < three years), preschool age (three to < five years) and school age (five to < 18 years) on cognitive and motor outcomes. Subgroup analyses focused on GA, birthweight, brain injury, time of commencement of the intervention, focus of the intervention and study quality. We used standard methodological procedures expected by Cochrane to collect data and evaluate bias. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

Forty-four studies met the inclusion criteria (5051 randomly assigned participants). There were 19 new studies identified in this update (600 participants) and a further 17 studies awaiting outcomes. Three previously included studies had new data. There was variability in the focus and intensity of the interventions, participant characteristics, and length of follow-up. All included studies were either single or multicentre trials and the number of participants varied from fewer than 20 to up to 915 in one study. The trials included in this review were mainly undertaken in middle- or high-income countries. The majority of studies commenced in the hospital, with fewer commencing once the infant was home. The focus of the intervention programmes for new included studies was increasingly targeted at both the infant and the parent-infant relationship. The intensity and dosages of interventions varied between studies, which is important when considering the applicability of any programme in a clinical setting. Meta-analysis demonstrated that early developmental intervention may improve cognitive outcomes in infancy (developmental quotient (DQ): standardised mean difference (SMD) 0.27 standard deviations (SDs), 95% confidence interval (CI) 0.15 to 0.40; P < 0.001; 25 studies; 3132 participants, low-certainty evidence), and improves cognitive outcomes at preschool age (intelligence quotient (IQ); SMD 0.39 SD, 95% CI 0.29 to 0.50; P < 0.001; 9 studies; 1524 participants, high-certainty evidence). However, early developmental intervention may not improve cognitive outcomes at school age (IQ: SMD 0.16 SD, 95% CI -0.06 to 0.38; P = 0.15; 6 studies; 1453 participants, low-certainty evidence). Heterogeneity between studies for cognitive outcomes in infancy and preschool age was moderate and at school age was substantial. Regarding motor function, meta-analysis of 23 studies showed that early developmental interventions may improve motor outcomes in infancy (motor scale DQ: SMD 0.12 SD, 95% CI 0.04 to 0.19; P = 0.003; 23 studies; 2737 participants, low-certainty evidence). At preschool age, the intervention probably did not improve motor outcomes (motor scale: SMD 0.08 SD, 95% CI -0.16 to 0.32; P = 0.53; 3 studies; 264 participants, moderate-certainty evidence). The evidence at school age for both continuous (motor scale: SMD -0.06 SD, 95% CI -0.31 to 0.18; P = 0.61; three studies; 265 participants, low-certainty evidence) and dichotomous outcome measures (low score on Movement Assessment Battery for Children (ABC) : RR 1.04, 95% CI 0.82 to 1.32; P = 0.74; 3 studies; 413 participants, low-certainty evidence) suggests that intervention may not improve motor outcome. The main source of bias was performance bias, where there was a lack of blinding of participants and personnel, which was unavoidable in this type of intervention study. Other biases in some studies included attrition bias where the outcome data were incomplete, and inadequate allocation concealment or selection bias. The GRADE assessment identified a lower certainty of evidence in the cognitive and motor outcomes at school age. Cognitive outcomes at preschool age demonstrated a high certainty due to more consistency and a larger treatment effect.

AUTHORS' CONCLUSIONS

Early developmental intervention programmes for preterm infants probably improve cognitive and motor outcomes during infancy (low-certainty evidence) while, at preschool age, intervention is shown to improve cognitive outcomes (high-certainty evidence). Considerable heterogeneity exists between studies due to variations in aspects of the intervention programmes, the population and outcome measures utilised. Further research is needed to determine which types of early developmental interventions are most effective in improving cognitive and motor outcomes, and in particular to discern whether there is a longer-term benefit from these programmes.

Sticky Mittens Training to Improve Reaching Skills and Manual Exploration of Full-Term and At-Risk Infants: A Systematic Review

AIM

To systematically review evidence of the effectiveness of sticky mittens training to improve reaching skills and manual exploration of full-term and at-risk infants and optimal training dosage.

METHODS

The Cochrane Collaboration and Preferred Reporting Items for Systematic Reviews and Meta-Analyses guided this systematic review. The electronic search was performed from September 2017 to August 2021 on PubMed, Scopus, Science Direct, and Cochrane databases. Eligibility criteria followed PICO terms: clinical trials investigating the effects of sticky mittens training on reaching skills and manual exploration of full-term and at-risk infants. PEDro scale and GRADE assessed methodological quality and quality of evidence, respectively.

RESULTS

Eight studies (313 children) were included. Five studies found statistically significant differences between experimental and control groups (62.6%). One study presented high methodological quality. Evidence synthesis showed very low and low evidence of the beneficial effects of sticky mittens training in full-term and at-risk infants, respectively.

CONCLUSIONS

Findings suggest that sticky mittens training facilitates reaching skills and manual exploration. However, results should interpretation with caution because studies targeted full-term infants. Future research should focus on infants at risk or with motor impairments since sticky mittens training seems to show positive effects and is easy to apply.

Effect of Contingency Paradigm-Based Interventions on Developmental Outcomes in Young Infants: A Systematic Review

PURPOSE

The purpose of this systematic review was to identify controlled trials evaluating the efficacy of contingency paradigm-based interventions to improve feeding, motor, or cognitive outcomes during the first year of life.

SUMMARY OF KEY POINTS

Seventeen studies, including 10 randomized controlled trials, incorporating contingency paradigm-based interventions were identified. Three of 3 trials reported improvements in nutritive sucking using pacifier-activated lullaby in preterm infants before term age. Seven of 12 trials reported improvements in reaching, manual exploration, and kicking behaviors in term and preterm infants; and 6 of 10 trials reported gains in early cognition using sticky mittens and contingent toys.

CONCLUSION AND RECOMMENDATIONS FOR CLINICAL PRACTICE

Contingency paradigm-based interventions can improve feeding outcomes in the neonatal intensive care unit in very preterm infants, and increase reaching, and perceptual-cognitive behaviors in term infants. Future research is needed to establish contingency paradigms as an effective early intervention strategy.

WHAT THIS ADDS TO THE EVIDENCE

This review synthesizes a body of literature on contingency paradigm-based interventions and highlights its potential paradigm-based interventions to improve developmental outcomes in infants.

A Pre-registered sticky mittens study: active training does not increase reaching and grasping in a swedish context

Several studies have previously investigated the effects of sticky mittens training on reaching and grasping development. However, recent critique casted doubts on the robustness of the motor effect of this training. The current study presents a pre-registered report that aimed to generalize these effects to Swedish infants. Three-month-old infants N = 96, 51 females, mostly White middle class in Uppsala, received daily, parent-led sticky mittens or observational training for 2 weeks or no training in 2019. Reaching and grasping abilities were assessed before and after training, using motion tracking and a 4-step reaching task. Sticky mittens training did not facilitate successful reaching. These results indicate that beneficial motor effects of sticky mittens training did not generalize to this sample.

Changes in cortical hemodynamics with the emergence of skilled motor ability in infants: An fNIRS study

The brain activity changes during infancy that underpin the emergence of functional motor skills, such as reaching and stepping, are not well understood. The current study used functional near-infrared spectroscopy (fNIRS) to examine the hemodynamic response across the frontal, mid-coronal plane (sensorimotor cortex) and external occipital protuberance (cerebellar cortex) regions of typically developing infants (5 to 13 months) during reach-to-grasp or supported treadmill stepping behaviour. Motor ability was assessed using the third edition of the Motor Subscale of the Bayley Scales of Infant Development (BSID-III). Infants with enhanced motor ability demonstrated greater oxy-hemoglobin (HbO) concentration in the contralateral anterior mid-coronal and frontal-dorsal areas during right-handed reach-to-grasp. During bilateral reaching behavior, infants with enhanced motor ability showed greater HbO increases in right frontal-dorsal regions and lower HbO increases in left anterior mid-coronal areas. In contrast, infants' motor ability was associated with changes in de-oxyhemoglobin (HbR) concentration in the ipsilateral anterior mid-coronal, contralateral frontal and left external occipital protuberance regions during left-handed reaching behavior. These relationships between upper limb hemodynamics and infant motor ability are consistent with increased lateralization and cognitive-motor coupling as motor skills emerge. During stepping behavior, infants with enhanced motor ability demonstrated smaller increases in HbR concentration in the bilateral external occipital protuberance region consistent with an emerging efficiency as cruising and independent stepping behavior is still nascent. Together, the current results identify several distinct neural markers of functional motor ability during infancy that may be relevant to diagnostic testing and rehabilitation of developmental movement disorders.

Spatial, But Not Temporal, Kinematics of Spontaneous Upper Extremity Movements Are Related to Gross and Fine Motor Skill Attainment in Infancy

Background: Spontaneous upper extremity movements in infancy provide insight on neuromotor development. Spatiotemporal kinematics have been used to evaluate typical development of reaching, a foundational motor skill in infancy. This study evaluates the relationship between spontaneous upper extremity movements, not elicited by a toy, and motor skill attainment. Methods: N = 12 healthy infants (2–8 months) participated in this longitudinal study (one to four sessions). Motor skills were assessed with the Bayley Scales of Infant and Toddler Development, 3rd Edition: gross motor subtest (GM) and fine motor subtest. Spontaneous upper extremity movements were collected using 3D motion capture technology. Infants were placed in supine for three to twelve 30-s trials, and their movements were recorded. Repeated measure correlation coefficients (Rmcorr) were used to evaluate relationships between variables. Results: There were significant, moderate, positive relationships between the straight distance from start to end of a movement and (a) fine motor score (Rmcorr = .55, p = .03), (b) GM score (Rmcorr = .63, p = .01), and (c) age (Rmcorr = .56, p = .02). There was a significant, moderate, negative relationship between straightness ratio and GM score (Rmcorr = −.52, p = .047). Discussion: Fine and GM skills are related to the straight distance from start to end of a movement and the straightness ratio of underlying spontaneous upper extremity movements.

Scaffolded reaching can encourage motor development: Commentary on van den Berg & gredebäck (2020)

Recent findings regarding the effectiveness of sticky mittens training as a motor intervention have been mixed. This commentary argues that despite inconsistent results, overall patterns suggest that sticky mittens may facilitate reaching behavior. More research on this topic is needed.

The sticky mittens paradigm: A critical appraisal of current results and explanations

Almost two decades ago, the sticky mittens paradigm was demonstrated as a way to train reaching and grasping behaviors in pre‐reaching infants, and consequently improve visual attentional abilities. In that first study, Needham and colleagues fitted 3‐month‐old infants with Velcro loop‐covered mittens and allowed them to interact with Velcro hook‐covered toys over the course of 2 weeks. In this review, we scrutinize the 17 studies that have followed those first sticky mittens results in regards to the motor, social perception, and visual attentional domains. Furthermore, we discuss the proposed mechanisms of the sticky mittens training. Current evidence strongly suggests that sticky mittens training facilitates social perception, which is consistent with prior correlational work showing links between action production and action perception. However, studies targeting motor and visual attentional abilities have too diverse results to warrant firm conclusions. We conclude that future research should focus on uncovering if there is a connection between sticky mittens training and motor behavior.

Play enhances visual form perception in infancy-an active training study

Motor experiences and active exploration during early childhood may affect individual differences in a wide range of perceptual and cognitive abilities. In the current study, we suggest that active exploration of objects facilitates the ability to process object forms and magnitudes, which in turn impacts the development of numerosity perception. We tested our hypothesis by conducting a preregistered active exploration intervention with 59 8-month-old infants. The minimal intervention consisted of actively playing with and exploring blocks once a day for 8 weeks. In order to control for possible training effects on attention, we used book reading as a control condition. Pre- and post-test assessments using eye-tracking showed that block play improved visual form perception, where infants became better at detecting a deviant shape. Furthermore, using three control tasks, we showed that the intervention specifically improved infants' ability to process visual forms and the effect could not be explained by a domain general improvement in attention or visual perception. We found that the intervention did not improve numerosity perception and suggest that because of the sequential nature of our hypothesis, a longer time frame might be needed to see improvements in this ability. Our findings indicate that if infants are given more opportunities for play and exploration, it will have positive effects on their visual form perception, which in turn could help their understanding of geometrical concepts.

Increasing task precision demands reveals that the reach and grasp remain subject to different perception-action constraints in 12-month-old human infants

The reach and grasp follow different developmental trajectories, but are often considered to have achieved nearly adult-like precision and integration by 12 months of age. This study used frame-by-frame video analysis to investigate whether increasing precision demands, by placing small reaching targets on a narrow pedestal rather than on a flat table, would influence the reach and grasp movements of 12-month-old infants in a complementary or differential fashion. The results reveal that placing the target atop a pedestal impaired the infants's ability to direct an appropriate digit towards the small target, but did not produce a corresponding decrease in the frequency with which they used an index-thumb pincer grip to grasp the target. This was due to the fact that, although infants were more likely to contact the target with a suboptimal part of the hand in the pedestal condition, a greater proportion of these suboptimal contacts ultimately transitioned to a successful index-thumb pincer grip. Thus, increasing task precision demands impaired reach accuracy, but facilitated index-thumb grip formation, in 12-month-old infants. The differential response of the reach and grasp to the increased precision demands of the pedestal condition suggests that the two movements are not fully integrated and, when precision demands are great, remain sensitive to different perception-action constraints in 12-month-old infants.

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.

Brief reaching training with "sticky mittens" in preterm infants: Randomized controlled trial

OBJECTIVE

To examine whether a brief reaching training with sticky mittens was effective to improve reaching behavior in newly reaching preterm infants.

METHODS

In this randomized controlled trial, twenty four 5-month-old (±16-week-old corrected age) preterm infants were randomly allocated into experimental or control groups. Infants were assessed three times in a single session: pretraining (immediately before training), posttraining (immediately after training), and retention (4 min after the posttraining). During training, infants in the experimental group wore open fingers Velcro covered mittens. Training consisted of one 4-minute session of stimulated reaching using Velcro covered toys. Controls did not receive the training. During assessments, infants were placed in a baby chair and toys without Velcro were offered at their midline for 2 min. Number of total reaches, proximal adjustments and distal adjustments of reaching were primary outcomes. Grasping was a secondary outcome.

RESULTS

Groups were similar in the pretraining. In the posttraining, trained infants performed greater amount of total reaches and bimanual reaches than untrained infants. Greater amount of bimanual reaches in trained infants was maintained in the retention test. Distal adjustments and grasping outcome were not influenced by the training.

CONCLUSIONS

A brief-term training with open fingers sticky mittens benefited reaching behavior and favored retention of increased bimanual reaches in newly reaching late preterm infants. However, it was not sufficient to influence hand openness and early grasping.

Touch the table before the target: contact with an underlying surface may assist the development of precise visually controlled reach and grasp movements in human infants

Multiple motor channel theory posits that skilled hand movements arise from the coordinated activation of separable neural circuits in parietofrontal cortex, each of which produces a distinct movement and responds to different sensory inputs. Prehension, the act of reaching to grasp an object, consists of at least two movements: a reach movement that transports the hand to a target location and a grasp movement that shapes and closes the hand for target acquisition. During early development, discrete pre-reach and pre-grasp movements are refined based on proprioceptive and tactile feedback, but are gradually coordinated together into a singular hand preshaping movement under feedforward visual control. The neural and behavioural factors that enable this transition are currently unknown. In an attempt to identify such factors, the present descriptive study used frame-by-frame video analysis to examine 9-, 12-, and 15-month-old infants, along with sighted and unsighted adults, as they reached to grasp small ring-shaped pieces of cereal (Cheerios) resting on a table. Compared to sighted adults, infants and unsighted adults were more likely to make initial contact with the underlying table before they contacted the target. The way in which they did so was also similar in that they generally contacted the table with the tip of the thumb and/or pinky finger, a relatively open hand, and poor reach accuracy. Despite this, infants were similar to sighted adults in that they tended to use a pincer digit, defined as the tip of the thumb or index finger, to subsequently contact the target. Only in infants was this ability related to their having made prior contact with the underlying table. The results are discussed in relation to the idea that initial contact with an underlying table or surface may assist infants in learning to use feedforward visual control to direct their digits towards a precise visual target.

Early human motor development: From variation to the ability to vary and adapt

This review summarizes early human motor development. From early fetal age motor behavior is based on spontaneous neural activity: activity of networks in the brainstem and spinal cord that is modulated by supraspinal activity. The supraspinal activity, first primarily brought about by the cortical subplate, later by the cortical plate, induces movement variation. Initially, movement variation especially serves exploration; its associated afferent information is primarily used to sculpt the developing nervous system, and less to adapt motor behavior. In the next phase, beginning at function-specific ages, movement variation starts to serve adaptation. In sucking and swallowing, this phase emerges shortly before term age. In speech, gross and fine motor development, it emerges from 3 to 4 months post-term onwards, i.e., when developmental focus in the primary sensory and motor cortices has shifted to the permanent cortical circuitries. With increasing age and increasing trial-and-error exploration, the infant improves its ability to use adaptive and efficicient forms of upright gross motor behavior, manual activities and vocalizations belonging to the native language.

The Embodied Origins of Infant Reaching: Implications for the Emergence of Eye-Hand Coordination

This article reviews the literature on infant reaching, from past to present, to recount how our understanding of the emergence and development of this early goal-directed behavior has changed over the decades. We show that the still widely-accepted view, which considers the emergence and development of infant reaching as occurring primarily under the control of vision, is no longer sustainable. Increasing evidence suggests that the developmental origins of infant reaching is embodied. We discuss the implications of this alternative view for the development of eye-hand coordination and we propose a new scenario stressing the importance of the infant body-centered sensorimotor experiences in the months prior to the emergence of reaching as a possible critical step for the formation of eye-hand coordination.

Precursors to language development in typically and atypically developing infants and toddlers: the importance of embracing complexity

In order to understand how language abilities emerge in typically and atypically developing infants and toddlers, it is important to embrace complexity in development. In this paper, we describe evidence that early language development is an experience-dependent process, shaped by diverse, interconnected, interdependent developmental mechanisms, processes, and abilities (e.g. statistical learning, sampling, functional specialization, visual attention, social interaction, motor ability). We also present evidence from our studies on neurodevelopmental disorders (e.g. Down syndrome, fragile X syndrome, Williams syndrome) that variations in these factors significantly contribute to language delay. Finally, we discuss how embracing complexity, which involves integrating data from different domains and levels of description across developmental time, may lead to a better understanding of language development and, critically, lead to more effective interventions for cases when language develops atypically.

Motor training at 3 months affects object exploration 12 months later

The development of new motor skills alters how infants interact with objects and people. Consequently, it has been suggested that motor skills may initiate a cascade of events influencing subsequent development. However, only correlational evidence for this assumption has been obtained thus far. The current study addressed this question experimentally by systematically varying reaching experiences in 40 three-month-old infants who were not reaching on their own yet and examining their object engagement in a longitudinal follow-up assessment 12 months later. Results revealed increased object exploration and attention focusing skills in 15-month-old infants who experienced active reaching at 3 months of age compared to untrained infants or infants who only passively experienced reaching. Further, grasping activity after - but not before - reaching training predicted infants' object exploration 12 months later. These findings provide evidence for the long-term effects of reaching experiences and illustrate the cascading effects initiated by early motor skills.

Assessing the Impact of Movement Consequences on the Development of Early Reaching in Infancy

Prior research on infant reaching has shown that providing infants with repeated opportunities to reach for objects aids the emergence and progression of reaching behavior. This study investigated the effect of movement consequences on the process of learning to reach in pre-reaching infants. Thirty-five infants aged 2.9 months at the onset of the study were randomly assigned to 1 of 3 groups. Two groups received a 14-day intervention to distinct reaching tasks: (1) in a contingent group, a toy target moved and sounded upon contact only, and (2) in a continuous group, the toy moved and sounded continuously, independent of hand-toy contact. A third control group did not receive any intervention; this group's performance was assessed only on 2 days at a 15-day interval. Results revealed that infants in the contingent group made the most progress over time compared to the two other groups. Infants in this group made significantly more overall contacts with the sounding/moving toy, and they increased their rate of visually attended target contacts relative to non-visually attended target contacts compared to the continuous and control groups. Infants in the continuous group did not differ from the control group on the number of hand-toy contacts nor did they show a change in visually attended target versus non-visually attended target contacts ratio over time. However, they did show an increase in movement speed, presumably in an attempt to attain the moving toy. These findings highlight the importance of contingent movement consequences as a critical reinforcer for the selection of action and motor learning in early development. Through repeated opportunities to explore movement consequences, infants discover and select movements that are most successful to the task-at-hand. This study further demonstrates that distinct sensory-motor experiences can have a significant impact on developmental trajectories and can influence the skills young infants will discover through their interactions with their surroundings.

fNIRS: An Emergent Method to Document Functional Cortical Activity during Infant Movements

The neural basis underlying the emergence of goal-directed actions in infants has been severely understudied, with minimal empirical evidence for hypotheses proposed. This was largely due to the technological constraints of traditional neuroimaging techniques. Recently, functional near-infrared spectroscopy (fNIRS) technology has emerged as a tool developmental scientists are finding useful to examine cortical activity, particularly in young children and infants due to its greater tolerance to movements than other neuroimaging techniques. fNIRS provides an opportunity to finally begin to examine the neural underpinnings as infants develop goal-directed actions. In this methodological paper, I will outline the utility, challenges, and outcomes of using fNIRS to measure the changes in cortical activity as infants reach for an object. I will describe the advantages and limitations of the technology, the setup I used to study primary motor cortex activity during infant reaching, and example steps in the analyses processes. I will present exemplar data to illustrate the feasibility of this technique to quantify changes in hemodynamic activity as infants move. The viability of this research method opens the door to expanding studies of the development of neural activity related to goal-directed actions in infants. I encourage others to share details of techniques used, as well, including analyticals, to help this neuroimaging technology grow as others, such as EEG and fMRI have.

Postural variability and sensorimotor development in infancy

Infants develop skills through a coupling between their sensory and motor systems. Newborn infants must interpret sensory information and use it to modify movements and organize the postural control system based on the task demands. This paper starts with a brief review of evidence on the use of sensory information in the first months of life, and describes the importance of movement variability and postural control in infancy. This introduction is followed by a review of the evidence for the interactions between the sensory, motor, and postural control systems in typically development infants. The paper highlights the ability of young infants to use sensory information to modify motor behaviors and learn from their experiences. Last, the paper highlights evidence of atypical use of sensory, motor, and postural control in the first months of life in infants who were born preterm, with neonatal brain injury or later diagnosed with cerebral palsy (CP).

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.