About

Kari Kretch, PhD, PT, DPT, is an assistant professor at the USC Division of Biokinesiology and Physical Therapy. She is a physical therapist and developmental psychologist whose research focuses on perceptual-motor skills and processes of developmental change in infants with typical and atypical motor development. Her work includes studying children with or at risk for neurodevelopmental conditions such as cerebral palsy. The overall goal of her research is to promote exploration, learning, and global development in children with physical disabilities.

Research topics

• Medicine
• Psychology
• Developmental psychology
• Computer Science
• Audiology
• Physical medicine and rehabilitation
• Communication
• Medical education
• Neuroscience
• Psychiatry

Selected publications

• Everyday positioning experience in typically developing infants and infants with or at risk for cerebral palsy

  Research in Developmental Disabilities · 2026-04-04

  articleOpen access1st authorCorresponding
  PublisherOA PDFDOI

• Everyday positioning experience in typically developing infants and infants at risk for cerebral palsy

  OSF Preprints (OSF Preprints) · 2026-03-16

  other1st authorCorresponding
  Publisher

• Overground suspension walkers elicit more and higher quality stepping than treadmills: A longitudinal study of pre-walking infants with Down syndrome

  medRxiv · 2026-05-12

  articleOpen accessSenior author

  Abstract Importance Children with Down syndrome (DS), a genetic condition associated with neuromotor impairments, walk ∼1 year later than typically developing peers. Treadmill training is the most successful known intervention for accelerating walking onset in DS. Overground stepping with mobility devices better mimics critical properties of real-world walking, but it is unknown how overground stepping develops in pre-walking infants with DS. Objective We aimed to characterize the developmental trajectory of stepping quantity and quality in supported overground stepping compared to supported treadmill stepping. We also measured infants’ ability to self-propel in the walker. Finally, we assessed caregivers’ perspectives on both devices. Design We tested infants at 10, 13, 16, and/or 19 months of age. Setting This study occurred in a university laboratory in the United States. Participants We tested 31 pre-walking infants with Down syndrome across 69 sessions. Exposure At each session, infants completed four trials per task (treadmill and walker) and a test of self-propulsion in the walker. Main Outcomes and Measures We measured step quantity (overall step rate and alternating step rate), step quality (percentage of steps that were alternating, forward, and flat-landing), the ability to self-propel the walker, and caregiver perspectives on both devices. Results Step quantity increased with age and varied by task—infants took more steps per minute in the walker compared to the treadmill. Moreover, steps were of equal or higher quality in the walker. By 16 months, about half of infants could self-propel. Caregivers viewed both devices favorably, though the majority preferred the walker for home and/or community use. Conclusions Overground walkers promote more stepping than a treadmill in pre-walking infants with DS, with stepping of similar or higher quality. Caregivers feel positively about overground walkers. Relevance Overground stepping using a suspension walker shows promise as an intervention for pre-walking infants with Down syndrome.

  PublisherDOI

• Infant sitting status, sitting age, and everyday positioning experience across the transition to independent sitting

  OSF Preprints (OSF Preprints) · 2026-02-23

  otherSenior author
  Publisher

• Infant Sitting Status, Sitting Age, and Everyday Positioning Experience Across the Transition to Independent Sitting

  Infancy · 2025-11-01 · 1 citations

  articleOpen access1st authorCorresponding

  Positioning-the body's physical configuration and relations to supports and restraints-is a fundamental aspect of infants' everyday experiences. How do everyday positioning experiences (the amount of time spent in different positions during daily life) change with the acquisition of postural skills like sitting? This study investigated relations between sitting status (whether infants have achieved a sitting milestone), sitting age (amount of time before or after that milestone), and everyday positioning experience. Forty-three infants participated at 4, 5, 6, and/or 7 months of chronological age. Everyday experience was measured using Ecological Momentary Assessment: Caregivers reported infants' current position repeatedly throughout their daily activities. The best predictors of everyday sitting experience (proportion of responses in which the infant was in an unrestrained sitting position) were chronological age and overall sitting age, calculated from the first day infants sat using hands for support; hands-free sitting age, calculated from the first day infants sat without hands, did not uniquely contribute. Sitting experience supplanted supine experience, which decreased with overall sitting age; the effect of overall sitting age on prone experience varied with chronological age. Time restrained by an adult decreased only with chronological age, and time restrained by a device was not related to chronological or sitting age. Results suggest that the continuous development of sitting skill changes the positioning composition of infants' everyday unrestrained floor time.

  PublisherOA PDFDOI

• Effects of sitting support and positioning on infant–parent coordinated attention.

  Developmental Psychology · 2025-09-01 · 1 citations

  articleOpen access1st authorCorresponding

  Infant-parent coordination during play is an important facilitator of the development of language, attention, and social cognition. Although the dynamics of triadic interaction in the second year of life are well documented, less is known about how infants and parents coordinate attention earlier in development. Prior work has shown that pre-sitting infants often play facing away from their parents, making visual access to faces difficult. However, it is not yet known whether and how this might affect their ability to coordinate attention to objects. Twenty 5- to 7-month-old infants (10 sitters, 10 nonsitters; 11 girls; nine Hispanic/Latino) were observed while they played with a parent in two conditions: sitting on the floor and sitting in a supportive infant seat. Infants and parents wore head-mounted eye trackers to record their visual attention, and their manual actions were coded from video. In the seat, parents always placed their infants facing toward them, but when sitting on the floor, parents frequently placed their infants facing away to provide manual support from behind. Surprisingly, coordination of attention was not disrupted, but facilitated, when infants faced away from their parents. This was likely due to greater rates of hand-eye coordination for both infants and parents while facing away, which strengthened the validity of the "hand-following" pathway to coordinated attention. Therefore, infants and parents can maintain high degrees of coordination during play without being able to see each other's faces. This phenomenon may have implications for developmental trends in infant attention throughout the first year of life. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

  PublisherDOI

• Sitting and caregiver speech input in typically developing infants and infants with cerebral palsy

  PLoS ONE · 2025-05-23 · 5 citations

  articleOpen access1st authorCorresponding

  The development of independent sitting is associated with language development, but the learning experiences underlying this relationship are not well understood. Additionally, it is unknown how these processes play out in infants with motor impairments and delays in sitting development. We examined the real-time associations between sitting and caregiver speech input in 28 5-7-month-old infants with typical development and 22 7-16-month-old infants with cerebral palsy who were at a similar stage of early sitting development. We hypothesized that object labels would be more likely to co-occur with moments of optimal attention to the labeled object while sitting than while in other positions. Infants were video recorded in five minutes of free play with a caregiver. Coders transcribed caregivers' speech, identified instances of object labeling, and coded infants' and caregivers' attentional states during object labeling episodes. We found that caregivers labeled more objects while infants were sitting than while they were in other positions. However, object labels were not more likely to co-occur with infant attention, infant multimodal attention, or coordinated visual attention to the labeled object during sitting. Infants with cerebral palsy were exposed to fewer labels and were less likely to be attending to objects as they were labeled than infants with typical development. Our findings shed light on a possible pathway connecting sitting and language in typical and atypical development.

  PublisherDOI

• Development and Initial Outcomes of the Interdisciplinary ‘Early Identification and Intervention for Infants Network’ (Ei3) in Los Angeles

  Journal of Clinical Medicine · 2024-12-06 · 3 citations

  articleOpen access

  Background/Objectives: The Early Identification and Intervention for Infants (Ei3) Network is an interdisciplinary team dedicated to improving early detection and intervention of cerebral palsy (CP) in California. This paper describes the key (1) awareness-building and (2) capacity-building strategies utilized by the Ei3 Network in the first two years. Methods: Awareness-building methods included interactive conference discussions, resource deliverable creation, and the creation of a framework for dissemination. Capacity-building methods were hosting assessment training, gathering stakeholder feedback, and implementation training. All deliverables were created with a minimum of 3 review and revision cycles. We planned, hosted, and provided scholarships for training, including the Hammersmith Infant Neurological Examination (HINE), Prechtl’s GMA, and an implementation conference. Preliminary descriptive statistics and paired samples t-tests were performed on HINE training surveys. Results: Seven resource deliverables were created and distributed. A professional website, @steps2home.org, was launched. Online channels gained followers (146, Instagram; 198, X; 298, Mailchimp). Providers participated in various trainings: the Sykes Symposium on early detection and intervention (70), HINE (211), GMA Basic or Advanced (46), and Implementation Conference (six facilities from April 2023 to June 2024). HINE training participants reported increased ability to identify CP (p = 0.001), knowledge of (p = 0.004) early detection, ability to implement early detection guidelines (p < 0.001), and confidence in performing the HINE on the post-test (79.87%). Conclusions: The first two years of Ei3 resulted in increased awareness of the early detection guidelines through resources to help providers and families navigate complex care systems and dissemination through online and in-person strategies. We built capacity by training an increased number of providers to identify infants at risk of CP and implement the early detection guidelines. Engagement of stakeholders in focus groups, reviewing documents, and including a parent panel throughout the process increased the value of this work and should support the expansion of the network in the next year.

  PublisherOA PDFDOI

• Early Mobility and Crawling: Beliefs and Practices of Pediatric Physical Therapists in the United States

  Pediatric Physical Therapy · 2023-12-21 · 3 citations

  articleOpen access1st authorCorresponding

  PURPOSE: To characterize beliefs of pediatric physical therapists (PTs) in the United States regarding the role of crawling in infant development and clinical practice. METHODS: Pediatric PTs reported their beliefs about early mobility and crawling, clinical approaches related to early mobility and crawling, and agreement with the removal of crawling from the Centers for Disease Control and Prevention (CDC)'s updated developmental milestone checklists in an online survey. Analyses examined associations between information sources and beliefs, between beliefs and clinical approaches, and between beliefs and CDC update opinions. RESULTS: Most participants believed that crawling was important (92%) and linked to a variety of positive developmental outcomes (71%-99%) and disagreed with its removal from the CDC checklists (79%). Beliefs were linked with clinical approaches focused on promoting crawling and discouraging other forms of mobility. CONCLUSIONS: Further research is needed to determine whether pediatric PTs' beliefs and clinical practices are supported by evidence.

  PublisherOA PDFDOI

• START-Play Physical Therapy Intervention Indirectly Impacts Cognition Through Changes in Early Motor-Based Problem-Solving Skills

  Pediatric Physical Therapy · 2023-04-18 · 8 citations

  article

  PURPOSE: This study tested whether the Sitting Together and Reaching to Play (START-Play) physical therapy intervention indirectly impacts cognition through changes in perceptual-motor skills in infants with motor delays. METHODS: Participants were 50 infants with motor delays randomly assigned to START-Play plus Usual Care Early Intervention (UC-EI) or UC-EI only. Infants' perceptual-motor and cognitive skills were assessed at baseline and 1.5, 3, 6, and 12 months post-baseline. RESULTS: Short-term changes in sitting, fine motor skills, and motor-based problem-solving, but not reaching, predicted long-term changes in cognition. START-Play indirectly impacted cognition through motor-based problem-solving but not sitting, reaching, or fine motor skills. CONCLUSIONS: This study provided preliminary evidence that early physical therapy interventions that blend activities across developmental domains and are supported by an enriched social context can place infants on more optimal developmental trajectories.

  PublisherDOI

Frequent coauthors

• Sandra L. Willett

  Nebraska Medical Center

  33 shared

• Stacey C. Dusing

  University of Southern California

  33 shared

• Regina T. Harbourne

  Duquesne University

  32 shared

• Lin‐Ya Hsu

  32 shared

• Barbara Sargent

  28 shared

• Karen E. Adolph

  American Academy of Child and Adolescent Psychiatry

  16 shared

• Natalie A. Koziol

  6 shared

• John M. Franchak

  University of California, Riverside

  6 shared

Labs

• Learning, Development, and Rehabilitation LaboratoryPI

Education

• Other, Physical Therapy

  University of Southern California

  2010

• Ph.D., Biokinesiology

  University of Southern California

  2015