Describe human diversity factors
Understanding function and its aspects
We’ve come to see inclusive design as a set of perspectives and practices that champion human diversity. Take a moment to consider how you've benefited from solutions that were originally designed for someone with different abilities. Take note of your own permanent, temporary, or situational disabilities that prevent you from interacting with society. Observe how people with different circumstances are excluded from participating in something you can do without barriers. Being inclusive starts with changing our perception.
The goal of our inclusive design practice is to recognize the barriers before we implement them, and to create forms that facilitate the function of human diversity. Designers need to understand and discuss the aspects of function that can lead to barriers in interaction. It can be challenging to communicate the aspects of function learned from the people you’re working with when designing. By categorizing and describing human diversity factors, we can use a framework that outlines the cognitive, mobility, vision, hearing, speech, and sensory demands of the technology we all use daily. This framework illustrates the barriers a person may face when they experience a mismatched interaction between their level of abilities and the design of a product.
Before diving into the framework, we need to understand that barriers to accessibility can co-occur. This means that disabilities don’t often happen in isolation.
Conditions like a stroke can impact a person in various ways. They may have impaired coordination, and a degree of paralysis. Also, they might be affected cognitively and experience aphasia, and difficulties with processing and memory. A stroke can also cause blind spots or visual field loss. Conversely, a stroke may only impact one of these areas, and may resolve itself in a short period of time. Designing for co-occurring barriers can empower people to achieve more.
Here are some examples of multiple types of disabilities occurring simultaneously.
Cerebral palsy: this can affect a person in various ways, from mild to profound degrees of severity. While one person might be able to walk on their own, another may need to use a wheelchair for mobility. Coordination, fine motor skills, vision, and cognitive functions may also be affected. Someone with cerebral palsy may also have difficulty with producing clear speech or speech that’s loud enough for a speaker device to detect. In mild forms of cerebral palsy, a person might only experience one or two minor effects of the condition.
Autism: the symptoms of autism vary widely. Some people with autism are verbal and can communicate well, while others are non-verbal. Some can be hypersensitive to sensory stimuli; others may not detect even very intense sensory stimuli. On the other end of the spectrum, another person with autism might not have any sensory deficits.
Cataracts: these cause a clouding or loss of transparency in the eye, which might lead to overall decreased acuity or spots in the visual field. In some cases, cataracts can cause color blindness. Cataracts not only affect vision, but might also affect someone’s coordination and accuracy, because they're having trouble seeing what they’re interacting with. Symptoms can also include double or blurred vision, and sensitivity to light and screen glare.
Multiple conditions: a person with cataracts may also, for example, have arthritis that limits their mobility.
Let’s take a deeper look at the human diversity factors that makes up the framework.
What is cognition? It’s our ability to engage in problem solving, reasoning, decision-making, comprehension, application of knowledge, and attention to a task. Cognition involves: attention, awareness, focus, memory, judgment, processing (speed), processing (comprehension), problem solving, and reasoning. A person’s cognition can affect the way they learn—whether this is learning how to use a new device or learning new information in a classroom.
Many aspects of cognition are affected by another. If a person has difficulty with attention, or problems focusing after an interruption, this may lead to issues with comprehension. Similarly, if a person has trouble understanding information, it might be difficult to commit the information to memory. This could influence a person’s confidence and motivation in learning something new. Cognition is essential in every task we perform.
What is mobility? It’s our ability to move and use body parts effectively for desired tasks. It's influenced by strength, coordination, and physical anatomy. Mobility involves: grasp, fine motor skills, coordination, control (voluntary versus involuntary movement), speed, muscle tone, endurance, and posture.
Many aspects of mobility can affect the way in which someone interacts with the world around them. Our anatomy and muscles give us mobility, and they rely on signals from the brain. Mobility ranges from being able to perform gross movements with the arms and legs—like walking or reaching for things—to fine movements such as writing with a pen, typing on a keyboard, or using a touchscreen with a single pointer finger. When it’s hard to use big or small muscles in a coordinated, smooth, and intentional manner, it might be difficult to navigate an experience.
Mobility can be influenced by situational, temporary, progressive, or permanent conditions.
What is vision? It’s our ability to see and understand visual information from our environment that guides thought and movement. Vision limitations include: blindness (sightlessness), low vision (partially sighted), decreased acuity, visual field loss, color blindness, and photophobia (light sensitivity).
Vision is complex. It involves both the presence of sight and the brain’s ability to process the information the eyes see. Vision allows us to make decisions about the environment around us. We use our sight to guide movements—for example, to catch a ball or tie our shoes. It tells us things like how far away an object is—whether it’s an oncoming car or a tab on a screen. Vision guides us to complete many types of tasks. For example, inserting a USB into a port or knowing where to put our fingers on a keyboard. Vision can be affected in many ways. Differences in vision can range from being completely absent or blurry for some people, to perfectly clear for others.
Vision is influenced by both physical and neurological factors.
There are many conditions and disabilities that can affect a person’s vision. By creating effective solutions that optimize sensory information, we can make it easier to access an environment that might not otherwise be available.
What is hearing? It’s our ability to receive and understand audio from our environment to guide thought and movement. Hearing loss includes these types: mild, moderate/severe, profound, and asymmetrical.
Receiving and interpreting sound is another way in which we inform our decisions and actions. For someone with hearing loss, exclusion occurs when information is conveyed only through sound. The degree of hearing loss varies across a wide spectrum, constantly causing different types of barriers. As a result, solutions to these barriers must also be varied and allow the user to choose what’s most appropriate for them. For example, someone with moderate hearing loss may benefit from using their Bluetooth-enabled hearing aids as a means of listening to video content instead of only having the option of reading closed captioning.
Users should be able to enhance their experiences to match their needs, without having to resort to solutions that fall short or surpass them.
Voice, speech and communication
What is voice, speech, and communication? It’s our ability to communicate information to effectively interact with our environment. Voice, speech, and communication limitations include: aphasia (receptive), aphasia (expressive), speech quality, social participation, and non-verbal.
Our ability to communicate (verbally or non-verbally) is essential in expressing wants and needs, forming relationships, conveying information to others, and interacting with our environment. Our ability to produce speech is determined by a complex sequence of physical and cognitive demands. Cognitive disabilities may cause difficulty with communication. Some disabilities don’t affect a person cognitively. However, they may cause difficulties with strength and coordination of mouth movement. This could affect the ability to produce speech that's clear enough or loud enough to be understood. A person with hearing loss may also choose to communicate through non-verbal means.
Sensation and perception
What is sensation and perception? It’s our ability to detect stimuli that affect our senses—such as touch, pain, vestibular sound, or sight—and the ways in which our body understands and reacts to them. Sensation limitations include: vestibular, chronic pain, skin integrity, sensation (hypersensitive and hyposensitive), and proprioception.
Sensation is our ability to detect senses like touch, pain, vision, or the movement and positioning of our body. Perception is the way in which the brain processes and communicates these senses to the rest of the body. Some people might have difficulty detecting sensation at all due to skin integrity or anatomical factors. Others can detect sensation—however, the way their brain processes sensory input might not be perceived accurately. For example, some people are more sensitive to vestibular input, such as spinning or motion, than others. Two people may be spinning for the same amount of time and at the same speed, but only one of them feels sick.
This principle can be applied to things like perception of pain, or perception of touch in general. Someone who is hyper responsive to touch might be annoyed by certain fabrics or textures of objects. In contrast, someone who is under responsive to touch may not realize their skin is becoming irritated from brushing up against the edge of their keyboard. The ability to sense stimuli is different than the way the body interprets it.
Regardless, a variance in either of these two processes might result in exclusion or discomfort during product experience.
The human diversity factors outlined above, and their aspects, help provide a framework to support designers’ education and exploration into inclusive design. Using this structure can help guide and educate while creating awareness of key insights and information. It’s also vital to re-iterate that these barriers can, and often do, co-occur. Ultimately, these factors are meant to be used as a resource to identify potential barriers a person might encounter. It’s also important to remember this list is not complete and will continue to grow and adapt over time. Exploring, understanding, defining additional factors, then weaving these details together to better understand people with disabilities, can lead to improved and more comprehensive design outcomes.