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Accessibility & Inclusivity

Accessible charts and graphs

September 5, 2023 12:45 PM
Long Lecture
🇬🇧 English
Bratysława 2

About

In the current information age, data visualizations need accessibility just as any other content type. Whilst we rave over supplying images with alternative text and providing closed captions or audiodescriptions for multimedia, barely anyone seems to consider the accessibility of the ever growing mound of data visualizations in our everyday news feeds. Charts and graphs are a huge accessibility challenge, but obiding by a few simple rules can greatly improve the user experience of many special needs groups - especially the visually impaired and users with cognitive deficits - enhancing the experience for all of us at the same time.

Talk by

Photo of Dorota Orzeszek, Senior UX Researcher & Accessibility Specialist at Aplikacje Krytyczne sp. z o. o.
Dorota Orzeszek
Senior UX Researcher & Accessibility Specialist at Aplikacje Krytyczne sp. z o. o.

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From the recording

Talk in brief

At WaysConf 2023, Dorota Orzeszek delivers a practical overview of making charts and data visualizations accessible to users with visual and cognitive impairments. Although Web Content Accessibility Guidelines (WCAG) only mandate basic alternative text and raw data tables, conventional charts regularly fail users due to inadequate contrast, tiny legend keys, and high cognitive overhead. Orzeszek advocates for choosing simple chart types, replacing rainbow palettes with monochromatic scales or patterns, enlarging legend swatches, and placing labels directly on chart elements using connector lines. She also demonstrates how subtle spacing and thicker segment borders resolve adjacent color confusion. Finally, she emphasizes pairing complex visualizations with plain-text summaries and structured tables so that essential data insights remain accessible regardless of visual acuity or cognitive aging.

Key takeaways

  1. 01

    Simple Chart Selection

    Designers should choose the simplest chart format suitable for their dataset instead of choosing complex layouts for aesthetic appeal. Selecting straightforward formats like pie or bar charts minimizes cognitive effort for readers.

    Watch from 12:13
  2. 02

    Monochromatic Palette Prioritization

    Rainbow scales create misleading contrast changes and confuse colorblind viewers across different hue perceptions. Monochromatic palettes and patterned textures reliably communicate data intensity by adjusting lightness rather than color.

    Watch from 15:55
  3. 03

    Enhanced Legend Swatches

    Enlarging color swatches in map keys helps users with low vision distinguish adjacent categories easily. Including overall summary figures directly inside legends eliminates extra cognitive steps required to decode visual regions.

    Watch from 19:51
  4. 04

    Segment Borders and Spacing

    Adding explicit spacing or thicker borders between chart sections prevents neighboring colors from merging under glare or visual fatigue. This small design adjustment significantly clarifies boundary lines across pie slices and bar charts.

    Watch from 28:04
  5. 05

    Content-First Text Summaries

    Alternative text and written chart descriptions must highlight key variable names and data metrics rather than superficial visual styling. Combining clear text summaries with structured HTML data tables ensures full accessibility for screen reader users.

    Watch from 30:43
Read edited transcript highlights

These concise notes were edited from automatic captions and checked against the talk structure. They are not a verbatim transcript.

Broad Impact of Visual and Cognitive Impairments

Data visualization accessibility affects far more people than just those with total blindness. Visual impairments span a wide spectrum including color vision deficiencies, low vision, and temporary eye strain from daily screen use. Furthermore, cognitive changes associated with natural aging impact working memory, processing speed, and data interpretation skills for a significant portion of the population over age 65. Accessible chart design helps counterbalance these common challenges, ensuring that critical insights remain understandable to users across different age groups and ability levels.

Watch from 3:55

Practical Pitfalls of Rainbow Scales

Rainbow color scales remain popular across maps and complex charts, but they present major accessibility barriers. Because rainbow schemes place darker shades at the ends and lighter shades in the center, they create non-intuitive contrast variations that confuse colorblind individuals. Color vision deficiencies vary widely, meaning two colorblind users might perceive blue or green hues in entirely different ways. Replacing rainbow scales with monochromatic palettes relies on varying lightness rather than hue, making intensity levels far easier to distinguish for low-vision and colorblind audiences.

Watch from 13:20

Reducing Cognitive Steps with Smart Legends

Standard map keys and chart legends often feature tiny color swatches that are difficult for low-vision users to identify. Increasing the surface area of color swatches makes hue identification drastically easier. Additionally, embedding total values or percentages directly alongside legend labels significantly reduces cognitive friction. Rather than forcing users to repeatedly cross-reference colors between the legend and the main graphic, displaying key metrics in the key allows readers to absorb essential data points in fewer steps.

Watch from 17:53

Utilizing Spacing and Thicker Borders

Chart elements frequently blend together when adjacent colors lack sufficient contrast or when screens are viewed under harsh lighting conditions. UX designers can resolve this issue by applying subtle spacing between pie slices or column bars, as well as adding distinct segment borders. Separating adjacent chart regions clearly defines where one data variable ends and another begins. Maintaining a contrast ratio of at least three to one between neighboring colors further improves legibility for users experiencing eye fatigue.

Watch from 26:40

Prioritizing Raw Data in Alternative Text

Writing alternative text for data visualizations requires focusing on underlying facts rather than visual styling. Screen reader users gain little value from descriptions mentioning bar shapes or 3D effects; instead, alternative text should directly convey key variable names and their corresponding values. Supplementing graphics with structured HTML data tables provides a complete, accessible reference. When paired with a clear two-sentence summary in the main body text, the visual chart itself becomes secondary, ensuring full comprehension for all readers.

Watch from 30:03

Relying on Tables for Precise Estimates

When answering an audience query regarding monochromatic color scales, Orzeszek highlights that while monochrome palettes work well for rough visual estimates, they cannot convey high-precision data across many adjacent regions. In scenarios requiring exact figure comparisons, supplementary data tables serve as the ultimate accessible source of truth. Designers should view complex graphics as decorative visual aids while embedding detailed data tables and interactive tooltips to support users requiring exact metrics or screen reader compatibility.

Watch from 35:51
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