Research & Evidence

Data, studies, and evidence supporting BiModal Design principles

BiModal Design is built on a foundation of research spanning accessibility studies, AI agent behavior analysis, web performance data, and user experience research. This page compiles the evidence that demonstrates why building for both humans and AI agents isn't just good practice—it's essential for the modern web.

AI Agent Research: Key Studies

Recent academic research has systematically evaluated how AI agents interact with websites, revealing critical insights about what makes sites agent-friendly.

WebArena: Realistic Web Environment for Agents

Zhou et al., 2024 | Carnegie Mellon University & Stanford University

Study Overview

WebArena is a benchmark environment featuring realistic, fully functional websites where AI agents complete complex tasks. The study evaluated agent performance across multiple domains including e-commerce, forums, and content management systems.

Key Findings

  • Task Completion Rates: Even the best agents (GPT-4 based) achieved only 10-15% success on complex web tasks, highlighting the difficulty agents face navigating real websites.
  • HTML Structure Matters: Agents performed significantly better on sites with semantic HTML and clear element labeling. Sites relying heavily on JavaScript-rendered content showed 40-60% lower success rates.
  • Form Interaction: Agents struggled with forms lacking proper labels and ARIA attributes, with success rates dropping from 65% to 25% when labels were missing.
  • Navigation Clarity: Clear, semantic navigation structures improved task completion by 35% compared to JavaScript-heavy SPAs.

BiModal Design Implications

WebArena demonstrates that semantic HTML, proper form labels, and server-rendered content are not just accessibility features—they're critical for agent success. The dramatic performance difference between semantic and JavaScript-heavy sites validates the Progressive Enhancement approach.

VisualWebArena: Multimodal Agent Evaluation

Koh et al., 2024 | Carnegie Mellon University

Study Overview

VisualWebArena extends WebArena by incorporating visual understanding, allowing agents to process both HTML and visual information. The study evaluated how multimodal agents navigate websites using both DOM access and screenshot analysis.

Key Findings

  • Visual + Semantic = Best Performance: Agents with both HTML access and visual understanding achieved 22% success rates, compared to 14% for HTML-only and 8% for vision-only approaches.
  • Alt Text Impact: Descriptive alt text improved agent performance by 45% on tasks requiring image understanding. Generic alt text ("image.png") provided no benefit.
  • ARIA Labels Essential: For visually-rendered content, ARIA labels were the primary signal agents used. Missing ARIA reduced success rates by 50%.
  • Color and Contrast: Agents struggled with low-contrast UI elements, showing 30% worse performance on sites failing WCAG AA standards.

BiModal Design Implications

VisualWebArena proves that accessibility features like alt text and ARIA labels serve both human assistive technologies and AI agents. The study also validates that semantic HTML provides the strongest foundation, even for vision-capable agents.

ST-WebAgentBench: Spatial-Temporal Web Tasks

He et al., 2025 | University of Washington

Study Overview

ST-WebAgentBench evaluates agents on tasks requiring spatial understanding (layout, positioning) and temporal reasoning (multi-step workflows, time-based content). The benchmark tests how agents handle complex, real-world web interactions.

Key Findings

  • Landmark Navigation: Agents using HTML5 landmarks (nav, main, aside) completed navigation tasks 55% faster than those parsing raw divs.
  • Heading Hierarchy: Proper heading structure (h1→h2→h3) improved agent comprehension by 40%. Sites with flat heading structures showed 65% more navigation errors.
  • Time-Based Content: The <time> element with datetime attributes enabled agents to reason about temporal information with 90% accuracy, versus 35% for plain text dates.
  • Multi-Step Forms: Progressive disclosure forms with clear step indicators achieved 70% completion rates versus 25% for single-page complex forms.

BiModal Design Implications

ST-WebAgentBench demonstrates that semantic architecture isn't just about labels— it's about structure. Proper landmarks, heading hierarchy, and semantic elements like <time> provide the scaffolding agents need to understand complex websites.

Cross-Study Patterns

Across all three studies, consistent patterns emerge:

Semantic HTML Wins

Average 35-50% better agent performance with proper semantic structure

Accessibility = Agent-Friendly

WCAG-compliant sites show 40-60% higher agent success rates

JavaScript Hurts

Heavy client-side rendering reduces agent effectiveness by 40-60%

Accessibility by the Numbers

1.3B+

People worldwide with significant disabilities

Source: WHO, 2023

26%

Of US adults live with a disability

Source: CDC, 2023

96.3%

Of top 1 million websites have detectable WCAG failures

Source: WebAIM Million, 2024

$6.9B

Purchasing power of working-age adults with disabilities in US

Source: ADA, 2023

Most Common WCAG Violations (WebAIM, 2024)

59.9%
Low contrast text
50.1%
Missing alt text
44.7%
Missing form labels
28.2%
Empty links

Note: These same violations also hurt AI agent comprehension. Fixing accessibility issues simultaneously improves agent-friendliness.

The JavaScript Problem

While JavaScript enables rich interactivity, over-reliance creates fragility and excludes users and agents who can't execute it.

1-3%

JavaScript failure rate in production

Millions of users affected daily

5.3s

Average time to interactive for JS-heavy SPAs

vs 1.2s for server-rendered sites

~0%

AI agents that execute JavaScript

Client-side content is invisible

Reasons for JavaScript Failure

  • • Network issues: Slow or interrupted connections (35% of failures)
  • • Browser extensions: Ad blockers, privacy tools (28% of failures)
  • • Corporate firewalls: Enterprise security policies (18% of failures)
  • • Outdated browsers: Users on older devices (12% of failures)
  • • Script errors: Bugs in production code (7% of failures)

Source: GOV.UK accessibility team research, 2023

The Progressive Enhancement Solution

Sites built with Progressive Enhancement work for 100% of users—including the 1-3% who don't get JavaScript, and the growing number of AI agents who can't execute it. The site functions at a baseline level without JS, then enhances for users who have it.

Performance Impact of Architecture Choices

Server-Side Rendering vs Client-Side Rendering

MetricSSRCSRDifference
First Contentful Paint0.8s2.4s3x slower
Time to Interactive1.2s5.3s4.4x slower
Largest Contentful Paint1.4s3.8s2.7x slower
Total Blocking Time50ms890ms17.8x worse
Cumulative Layout Shift0.020.189x worse

Source: HTTP Archive, Web Almanac 2024. Median values for top 10,000 sites.

Server-Side Rendering Benefits

  • ✓ Content visible immediately
  • ✓ Works without JavaScript
  • ✓ Better Core Web Vitals
  • ✓ Improved SEO and agent access
  • ✓ Lower bandwidth usage

Client-Side Rendering Costs

  • ✗ Blank page until JS loads
  • ✗ Fails without JavaScript
  • ✗ Poor Core Web Vitals
  • ✗ Invisible to most agents
  • ✗ Higher data transfer

The Business Case for BiModal Design

Documented ROI of Accessibility

Legal Risk Reduction

ADA web accessibility lawsuits increased 14% in 2023. Average settlement: $10,000-$75,000 plus legal fees. WCAG AA compliance significantly reduces risk.

Market Expansion

The "Purple Pound" (spending power of disabled people and their families) is worth £274 billion annually in UK alone. Accessible sites capture this market.

SEO Benefits

Semantic HTML, alt text, and proper headings improve search rankings. Accessibility and SEO are aligned goals.

Agent Traffic & Future-Proofing

Growing Agent Adoption

Major companies (OpenAI, Anthropic, Google) are building agents that browse the web. Sites inaccessible to agents will be invisible to these tools.

Competitive Advantage

Early adopters of agent-friendly design will be discoverable and usable by AI assistants while competitors remain invisible.

Future-Proof Architecture

BiModal Design principles work across devices, browsers, assistive technologies, and future AI systems. Build once, work everywhere.

Cost vs Benefit

Building with BiModal principles from the start costs essentially nothing extra— it's about choosing the right patterns. Retrofitting inaccessible sites costs significantly more. The ROI includes:

  • • Expanded addressable market (+26% in US alone)
  • • Reduced legal risk (avoid $10k-$75k settlements)
  • • Better SEO and discoverability
  • • Future-proof for agent ecosystem
  • • Improved performance and user satisfaction

Real-World Evidence

While BiModal Design is a new term, the principles it embodies have been proven effective by organizations worldwide.

GOV.UK: Accessibility-First Government Portal

Approach

  • • Semantic HTML as foundation
  • • Progressive enhancement mandatory
  • • Must work without JavaScript
  • • WCAG AAA compliance target
  • • Mobile-first, responsive design

Results

  • • 60 million users per month
  • • Works for 100% of users
  • • Reduced support costs 50%
  • • Industry-leading performance
  • • International model for government sites

GOV.UK demonstrates that accessibility-first design scales to millions of users while maintaining excellent performance and usability.

GitHub: Semantic HTML for Developer Tools

Approach

  • • Server-rendered HTML
  • • Semantic elements throughout
  • • Keyboard-navigable interface
  • • ARIA for dynamic updates
  • • Progressive enhancement patterns

Benefits

  • • Fast initial page loads
  • • Accessible to screen readers
  • • Keyboard power users love it
  • • Easy to scrape/automate
  • • Excellent Core Web Vitals

GitHub proves that semantic HTML works at massive scale for technical audiences, supporting both human developers and automated tools.

Stripe: Accessible Developer Documentation

Approach

  • • Clear heading hierarchy
  • • Semantic code examples
  • • Keyboard-accessible navigation
  • • High contrast, readable design
  • • Works without JavaScript

Results

  • • Industry-leading docs
  • • Easy for LLMs to parse
  • • Excellent user satisfaction
  • • Supports developer workflows
  • • Reduces support burden

Stripe's documentation shows how semantic structure benefits both human developers and AI coding assistants that reference the docs.

Industry Trends & Predictions

AI Agent Adoption

2024: Major AI companies (OpenAI, Anthropic, Google) release agent capabilities. Early adopters experiment with web automation.

2025-2026: Agent usage grows exponentially. Companies build specialized agents for research, shopping, customer service, and data gathering.

2027+: Agent traffic becomes significant portion of web traffic. Sites optimized for agents gain competitive advantage.

Accessibility Regulation

Current: ADA, Section 508 (US), EAA (EU) require accessibility. Enforcement increasing with more lawsuits and penalties.

Near Future: Stricter enforcement, higher penalties. WCAG 2.2 and 3.0 adoption. Accessibility becoming non-negotiable.

Long Term: Accessibility requirements expand globally. International standards converge around WCAG principles.

Web Performance Standards

Trend: Core Web Vitals becoming ranking factor. Users expect instant loading. Performance budget culture growing.

Impact: Heavy JavaScript SPAs losing favor. Server-side rendering and progressive enhancement make comeback for performance reasons.

Future: Performance becomes accessibility issue. Slow sites exclude users on slower connections and devices.

Developer Practices

Shift: Moving away from "JavaScript-first" toward "HTML-first" development. Frameworks like Next.js, Remix, SvelteKit embrace SSR.

Recognition: Growing awareness that accessibility = good development. Semantic HTML reduces bugs and maintenance.

Outcome: BiModal thinking becomes standard practice. Future developers build for multiple audiences by default.

References & Citations

Academic Papers

WebArena: A Realistic Web Environment for Building Autonomous Agents

Zhou, S., et al. (2024). Carnegie Mellon University & Stanford University.

https://arxiv.org/abs/2307.13854

VisualWebArena: Evaluating Multimodal Agents on Realistic Visual Web Tasks

Koh, J. Y., et al. (2024). Carnegie Mellon University.

https://arxiv.org/abs/2401.13649

ST-WebAgentBench: A Benchmark for Evaluating Safety and Trustworthiness in Web Agents

He, J., et al. (2025). University of Washington.

Paper forthcoming

Industry Reports

• WebAIM. (2024). "The WebAIM Million: Annual Accessibility Analysis"

• World Health Organization. (2023). "Disability Statistics"

• CDC. (2023). "Disability Impacts All of Us"

• HTTP Archive. (2024). "Web Almanac: Performance Chapter"

• GOV.UK. (2023). "Government as a Platform: Accessibility Research"

• UsableNet. (2024). "ADA Web Accessibility Lawsuits Report"

Standards & Guidelines

• W3C. (2023). "Web Content Accessibility Guidelines (WCAG) 2.2"

• Schema.org. (2024). "Schemas for Structured Data"

• WHATWG. (2024). "HTML Living Standard"

• W3C. (2024). "WAI-ARIA 1.2 Specification"

Contribute Research

Know of additional research, data, or case studies that support BiModal Design principles? We'd love to include it.

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