Add visible instructions for every chart interaction

Add visible instructions anywhere a chart supports interaction. For example, state how to hover or select with a mouse, and list the keyboard actions used to move between visuals, enter a chart or filter, and make a selection.

Visible interaction instructions make hidden controls discoverable across input modes. They reduce guesswork about how to enter an interactive chart, move among controls, and complete selections.

Mechanism: When interaction instructions are shown in the interface, users do not have to infer whether a chart is interactive or guess which keys or pointer actions are supported.

Evidence: Chartability marks missing interaction cues or instructions as a critical operability failure and requires any interactive chart to explain its controls, including keyboard controls (Elavsky et al., 2022). WCAG guidance requires labels or instructions for interactive controls, and the cited accessible dashboard example provides explicit key instructions for navigation, entry, and selection (W3C, n.d.; SF COVID-19 Data and Reports – Dashboard Accessibility Information, n.d.).

Notes: Do not rely on the assumption that good visual design makes interaction self-evident.

• User Goal: Operate an interactive chart or dashboard control.
• Task: Enter a chart, navigate between visuals, or select or filter options.
• Chart Setting: The chart has interactive behavior such as hover, selection, filtering, or keyboard navigation.
• Audience: People using keyboard input, including screen reader users, and people who benefit from explicit instructions.
• Success Criterion: A user can discover that interaction exists and identify the required keys or pointer actions before trial and error.

Break it when: The chart is fully static and exposes no interactive behavior. Why: The requirement is scoped to charts that have interactive capabilities.

Sacrifice: The chart must carry extra explanatory text. Risk: Partial instructions can still leave keyboard interaction undiscoverable. Mitigation: Document every supported interaction mode, including keyboard controls.

Mistake: Assuming users will infer interactive behavior from the design and omitting visible instructions. Why it fails: Hover, keyboard, or selection behavior remains hidden to users who do not explore the chart the same way.

Failure Sign: The chart responds to hover, focus, tab, arrow keys, Enter, or Space, but no visible text explains those actions. Quick Check: Look for instructions before interacting. If you cannot tell how to enter, move, or select with the keyboard, the chart fails. Stronger Test: Use only the keyboard to navigate the visualization and verify that every working key action is named in the instructions.

• Add a visible instruction block that states the chart is interactive and where interaction applies.
• List each supported keyboard action, including how to move, enter, and select.
• Name the matching pointer action when the chart supports hover or mouse selection.
• If interaction spans several visuals or filters, explain how users move between them before they operate the chart.