Participants' photos will be taken in a supine position and parts of the initial PT evaluation and re-evaluation sessions will be video recorded for future analyses by an assessor blind to the infants' group assignment. Such analyses will include still photography measurements, assessment of motor development using the Alberta Infant Motor Scale (AIMS), and assessment of symmetrical use of both sides of the body using the Functional Symmetry Observation Scale (FSOS). Treating therapists will perform "live" active head rotation and muscle strength measurements, for which assessor blinding will not be possible. In addition, each infant's behavior exhibited during therapy will be assessed by the treating therapist at intervention sessions 2-4. Results obtained from the two groups will be compared.