Human Factors Analysis : Evaluating Safety and Risk Associated With Baby Walkers

As a part of the Human Factors in Product Design class, I completed a project on conducting an ergonomic assessment of a physical product. I decided to evaluate baby walkers for the following reasons:

1. While some countries like Canada have banned baby walkers altogether, they are used widely in the USA, India and many other countries.
2. Although there is some anecdotal evidence and research studies suggesting the detrimental effects of baby walkers, I could not find an exhaustive human factors analysis on the topic.
3. Evaluating baby walkers gave me opportunity to learn the constraints of Human Centered Design for a very specific user group — infants between the age 6 months to 2 years.

This blog post covers some of the background research, the human factors methods that I applied to the analysis and my biggest learnings from the project.

Background

Using Baby Walkers Could Delay Motor Development

Baby walkers are often used by parents for children between the age of 6 and 15 months under the impression that it will assist the baby in learning to walk. When placed in a walker, the baby uses the muscles mostly in the back of the leg. This is especially true in the beginning as they will often push forward leaning their chest on the support surface and rise up on tip-toes to move the device using both feet together. This position does not allow the same use of the muscles at the front of the legs or the use of tummy muscles. Walking requires equal use and strength of both the front and back leg muscles. In a baby walker, the baby’s balance point or center of gravity is low, and it is lower when he or she is leaning forward in the equipment. Further, normal balance reactions and arms are not used in the same manner as normal walking.

They found infants who used walkers sat, crawled and walked later than non-users, and scored lower on Bayley scale of motor and mental skills.

One study on 109 infants between 6 to 15 months of age compared childern using baby walker versus those who did not, and analyzed their motor and mental development. They found infants who used walkers sat, crawled and walked later than non-users, and scored lower on Bayley scale of motor and mental skills. There were many other studies conducted to see the development of these skills in both the groups. This gave more evidence to suggest that baby walker interferes with locomotor skills and may cause development delay.

Using Baby Walkers Could Increase The Risk Of Accidents

Evidence as per world statistics shows that injuries caused by a baby walker are common. In 1999, an estimated 8800 children younger than 15 months were treated in hospital emergency departments in the United States for injuries associated with infant walkers. The vast majority of injuries occur from falls down stairs. This led to Canada banning baby walkers in 2004. But in some countries, more than 75% still use walkers. Walkers can pinch fingers and toes, tip over, collapse, fall into water, plunge down stairs, knock over baby gates, gather speed quickly (up to three feet per second), and make it easier for a baby to reach higher objects that could be dangerous (such as a hot cup of coffee, or a heavy or breakable object on a shelf).

The vast majority of injuries occur from falls down stairs. This led to Canada banning baby walkers in 2004.

While the anecdotal evidence and lab studies suggest the detrimental effects of baby walkers, I could not find an exhaustive human factors analysis of baby walkers. The next sections outline the original analysis that I conducted for the project.

The specific product that was found on Amazon and selected for the analysis was as follows:

Figure 1: Baby Walker Used in this analysis.

Weight: 5 pounds

Dimensions: 61 x 61 x 50.8 cm

Minimum suggested age by manufacturers: 6 months

Human Factors Evaluation: Functional Task Analysis

Task Analysis methods are some of the most important Human Factors methods and rely upon participant observations and expert analysis. Using products requires a complex sequence and hierarchy of actions and decisions. These actions and decisions can be broken into a list of tasks and sub-tasks. Each task and sub-task can then be evaluated for safety, comfort, and risk.

A baby walker consists of a wheeled base supporting a rigid circular frame that holds a fabric seat with leg openings and usually a plastic tray. Wheels on the base of the walker allow free movement in any direction. For the purpose of the Task Analysis, the tasks were defined as follows:

1 Ensuring the walker is stable and straight.

2 Lifting the child.

3 Seating the child in walker.

4 Adjusting each leg in the leg space.

5 Ensuring child’s’ legs point towards the floor.

6 Movement of legs by child.

7 Rotation of wheels of walker.

8 Displacement of walker in the direction in which force is applied and speed corresponding to the speed of movement of the legs.

Depending on the force applied and the smoothness of the service, the walker can move up to one meter per second.

The environment in which the baby walker is used does not have any impact in preventing the motor and cognitive changes that might be associated with the use of Baby Walkers. However, such factors can have significant impact on inducing injuries and accidents. Some of the environmental factors that were identified for safe operation of the Baby Walker are as follows:

1. First of all, the floor needs to be smooth, with no loose rugs that can catch on the wheels or bunch up beneath the walker. It is also a good idea to make sure that there is enough open area so that the baby walker doesn’t get stuck.
2. Check the playing area for anything dangerous or fragile that will be within the baby’s reach.
3. Any stairs should be blocked with a door or a sturdy baby gate to prevent the baby from accidentally going down them while in the walker.
4. Making sure there are no sharp edges that the baby could run into.
5. A baby walker should never replace parental supervision. In fact, as parents, we should stay in the room with a baby that is using a walker to prevent them from getting stuck or injured. The added mobility can allow the baby to get to places and reach things that were not accessible while crawling.

Human Factors Issues Identified From Task Analysis

Once the tasks were identified using the Functional Task Analysis, the next step was to break the tasks that had a dominant physical or cognitive component, and check if the Baby Walker under analysis met the recommended human factors criteria for those tasks. The criteria were determined using prior research evidence from the literature.

Physical Human Factors Issues

1. The product allows for free movement to an infant whose body system and strength may not be fully developed to carry his/her weight and move his/her legs in a walking pattern. Their legs are often hanging, putting extra strain on their hips and spine.
2. The wheels at the base can allow movement up to three feet per second depending upon the force applied, which can lead to accidents and injuries.
3. The product is available in standard sizes, and does not take into account that a child’s body grows significantly fast from 6 months to 15 months
4. It teaches babies to lean forward against the walker and push off on their toes, which is not natural.

Cognitive Human Factors Issues

• Baby walkers put babies in an unnatural standing position, which does not allow child to see where his/her feet are, when they walk. Being able to see our hands and feet as they move is important for brain development and proprioception

• A baby walker encourages infants to discover their environment at a different height before they can identify hidden dangers. This could potentially impact how children make sense of their physical environment and what sensory organs they use to do so.

Product Evaluation Summary

Based on the human factor concerns of the product, standard metrics have been used to evaluate the physical, cognitive and emotional ergonomics of the product.

Table 1: Physical Human Factors checklist

Cognitive Human Factors Checklist

Discussion

The first round of Task Analysis and Human Factors Evaluation showed several concerning issues about the motor development concerns that previous researchers have suggested as well as the safety concerns that have led countries like Canada to ban baby walkers. While a more granular Task Analysis could have been conducted, the identification of several high priority human factors issues did not deem a further analysis necassary.

Overall, the baby walker analyzed for this product was not designed to aid the infant in learning how to walk naturally, rather puts them in an odd position where they prematurely use their leg muscles to move around, which has proven to have a negative impact on the mental and motor development of kids. It can also lead to long term spinal implications (i.e., asymmetrical muscular imbalance). Apart from the developmental hazards, the product also poses the risk of getting injured in case the walker tips over or plunges down the staircase. Although certain design features have been improvised over a period of time to make the product more attractive, comfortable, user focused and safe with respect to managing speed, the basic mechanics of operation remains same and is unable to assist the child in walking in a natural manner.

Hence, based on this analysis, parents should reconsider their use of baby walkers and if they chose to use them, they should ensure that they increase the size of the baby walkers as the child develops between 6 months to 18 months.

Hence, based on this analysis, parents should reconsider their use of baby walkers and if they chose to use them, they should ensure that they increase the size of the baby walkers as the child develops between 6 months to 18 months.

Lessons Learnt

When I started my MS coursework in Human Factors and Ergonomics, my biggest assumption was that designing User Centered products would always require to interact with users. The biggest takeaways from this project was that

1. There are many techniques that make use of existing research and can be used to analyze and evaluate existing design solutions without necessarily talking to the users or asking for their feedback. Given that the users for baby walkers happen to be 1 year old toddlers, asking for feedback would not have worked anyways.
2. Therefore, relying on observations, prior research and holistic knowledge of Human Factors methods could be an important tool of analysis in product development.

Bibliography

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Karwowski, Waldemar, Marcelo M. Soares, and Neville A. Stanton. 2011. Human Factors and Ergonomics in Consumer Product Design: Uses and Applications. CRC Press.

“Limiting Time in ‘Walker’ Devices May Avoid Back Pain Later in Life.” 2017. http://www.pediatricservices.com/parents/pc-21.htm.

Lueder, Rani, and Valerie J. Berg Rice. 2007. Ergonomics for Children: Designing Products and Places for Toddler to Teens. CRC Press.

McCauley-Bush, Pamela. 2011. Ergonomics: Foundational Principles, Applications, and Technologies. CRC Press.

“Physical Characteristics of Children as Related to Death and Injury for Consumer Product Safety Design : May 1975, 241 Pp; Abstr in Government Reports Announcements (Report No PB-242 221/0GA) — Documents.” 2017.

Siegel, Andrea C., and Roger V. Burton. 1999. “Effects of Baby Walkers on Motor and Mental Development in Human Infants.” Journal of Developmental & Behavioral Pediatrics 20 (5): 355–360.

Siegler, Robert S., Judy S. DeLoache, and Nancy Eisenberg. 2003. How Children Develop. Macmillan.

Snyder, Richard G., and others. 1977. “Anthropometry of Infants, Children, and Youths to Age 18 for Product Safety Design. Final Report.” http://eric.ed.gov/?id=ED153998.

“Why Baby Walkers Are Banned In Canada.” 2017. The Huffington Post.