Synonyms

PDMS; PDMS-II; PDMS-2

Description

The Peabody Developmental Motor Scales-2 (PDMS-2; Folio & Fewell, 2000) is a criterion-referenced and norm-referenced developmental assessment comprised of two scales: the Gross Motor Scale and the Fine Motor Scale. The Gross Motor Scale includes four categories: reflexes, stationary gross motor skills, locomotion, and object manipulation. The reflex subtest is administered to children from birth through 11 months. It contains eight items that measure reactions to environmental events. The stationary subtest includes 30 items that measure equilibrium and sustained control of the body within the center of gravity. The locomotion subtest measures the child’s skills in moving from one place to another through 89 items that cover the developmental progression of various modes of movement. The object manipulation subtest includes 24 items that measure the ability to manipulate balls. Test items specifically measure skills such as:

  • Reflex integration and postural adjustments

  • Balancing on one foot and on tiptoes

  • Crawling, walking, running, jumping, and skipping

  • Throwing, catching, and kicking a ball

The Fine Motor Scale is comprised of two categories: grasping and visual-motor integration. The grasping subtest includes 26 items that measure the ability of the child to use hands independently or together. The visual-motor integration subtest contains 72 items that measure visual perceptual skills and eye-hand coordination. Test items specifically measure skills such as:

  • Demonstrating various grasp patterns as appropriate for different objects

  • Stacking or configuring blocks to replicate a demonstrated design

  • Manipulating buttons, using scissors, folding paper, and drawing to copy designs

A child’s performance on each test item is scored a 0, 1, or 2. A score of 0 indicates no success on the item, 1 indicates emerging abilities to complete the item, and 2 indicates mastery or success in meeting all criteria for the test item. Test scores can be calculated as percentiles, standard scores, and age equivalents for the Gross Motor Quotient, Fine Motor Quotient, and Total Motor Quotient.

As a performance-based measure, the PDMS-2 can be administered in approximately 20–30 min per scale and 45–60 min for the total test (Folio & Fewell, 2000).

Historical Background

The Peabody Developmental Motor Scales (PDMS; Folio & Fewell, 1983), originally published in 1983, consisted of a Gross Motor Scale and Fine Motor Scale which were normed for children ages 1–83 months. The scales could be used separately to measure the respective motor domain or used together to obtain an overall motor performance composite score. The test was widely used throughout North America and frequently referenced in the published literature. The PDMS was revised in the late 1990s in order to update test items and establish contemporary norms. Normative data were collected between 1997 and 1998 using a sample of 2,003 North American children representing four major geographic regions from 46 states and one Canadian province. The test continues to be widely used by occupational and physical therapists and can also be administered by diagnosticians, early intervention specialists, psychologists, and others with training in motor skill assessment.

Psychometric Data

Characteristics of the normative sample for the PDMS-2 were consistent with the 1997 US Census demographic data with respect to geographical area, gender, race, residence location (rural, suburban, urban), ethnicity, and socioeconomic status. Overall, the sample is considered representative of the US population at the time the test was developed. Scoring norms are available for typically developing children from birth through age 5 (1–84 months). No normative data are available for children with disability conditions.

Reliability. Internal consistency was evaluated using Cronbach’s coefficient alphas. Values ranged from 0.84 to 0.98 indicating strong associations among test items within the same construct (e.g., fine motor, gross motor). Measures of test-retest reliability were limited to two groups of young children ages 2 through 11 months (n = 20) and 12 through 17 months (n = 30). Resulting correlation coefficients ranged from 0.73 to 0.96, suggesting acceptable test-retest reliability within the items applicable to these age groups. Inter-rater reliability for test scores yielded coefficient values of 0.96 to 0.98. Inter-rater reliability for individual test items has not been examined.

Validity. Content validity of the PDMS-2 is supported through developmental theory and various item analysis techniques including item response theory and logistic regression. Age-related trends, such as increases in mean test scores occurring with increasing age, have been observed. The various subtests within each composite are supported through confirmatory factor analysis. Concurrent validity was examined between the PDMS-2 and the initial version of the test, the PDMS. The resulting correlations were strong with 0.84 for the fine motor composite and 0.91 for the gross motor composite. Moderate to strong correlations were also noted with scores from the gross and fine motor scales of the Mullen Scales of Early Learning: AGS Edition.

Clinical Uses

The PDMS-2 is often used in clinical and educational settings to assess gross and fine motor skills along the developmental trajectory (Richardson, 2010). The tool can be used to identify children with delays in motor skills and to plan intervention.