The Fourth Hemisphere: Marketing for AI

The Fourth Hemisphere: Marketing for AI

Your buyers ask AI before they ask you. We shape what it says.

ChatGPT, Claude, Gemini, Copilot, Perplexity, Google AI Mode, and Google AI Overviews now sit between your company and the people deciding whether to buy from it, invest in it, or cover it. The Fourth Hemisphere: Marketing for AI is Third Hemisphere's practice for that layer. Your existing marketing strategy is our starting input. We assess every area of it for AI visibility, measure how the seven engines represent your brand, and then direct the work across your in-house team and the agencies you already retain.

Why a fourth hemisphere

The human brain has two hemispheres, and Third Hemisphere has always been the third: the capability that gives a company higher-level language, intelligence, influence, and reach. AI is the fourth. Buyers, investors, journalists, and regulators now ask it what to think before they form their own view, and most companies have never checked what it says about them.

The audit comes first, and it costs you nothing

We run your category's real buyer questions through the engines your buyers use before we meet, then present what we found on the call: where you are named, who is named instead, your CRISP score, and the breaks behind it. Nothing is asked of you up front beyond a company website. Your marketing plan comes into it after we have spoken, when there is something concrete to work on.

Then we read your plan against what the engines do

Once the audit has landed, you share the marketing plan you already run, from positioning and SEO to content, paid media, PR, partnerships, and sales enablement. We assess every area against one question: does this earn accurate, prominent representation when an AI engine answers for your category? Each area returns a rating, the specific gap, and the change that closes it. Anything confidential can wait until after the first call.

We direct, your suppliers deliver

Third Hemisphere sits as the strategy layer across that plan. We set the AI-visibility standard, decide what moves first, and brief whoever executes, including the SEO, digital, web, or content agencies you already retain. Your suppliers keep doing what they do well, under one strategy governing how the whole picture reads to an engine.

Marketing with AI, and to AI

We market with AI: audit tooling, AI-assisted research, and reputation monitoring across the seven engines. And we market to AI: earned media the engines cite, structured content they can retrieve, and entity consistency they can trust. Fifty real buyer questions across ChatGPT, Claude, Gemini, Copilot, Perplexity, Google AI Mode, and Google AI Overviews score your brand with our CRISP methodology across Consensus, Reputation, Influence, Source, and Presence, then a 6 to 12 month programme moves the score, with quarterly re-audits proving the shift.

  • Your marketing strategy assessed area by area for AI optimisation
  • The Fourth Hemisphere Audit: 50 buyer questions across five AI engines
  • CRISP scoring across Consensus, Reputation, Influence, Source, and Presence
  • A strategy layer that sets the AI standard across every channel you run
  • Direction and management of your SEO, digital, web, and content agencies
  • Earned media programmes built for AI-engine citation
  • Structured, AI-ready content and entity consistency work
  • Quarterly re-audits that measure movement in the answers themselves

Our Marketing for AI Approach

  1. Strategy Intake You hand us the marketing strategy you are already running, together with the agencies and suppliers delivering it. That plan becomes the input to the audit, so every finding lands against work you have already committed to.
  2. Engine Audit We ask the seven engines, ChatGPT, Claude, Gemini, Copilot, Perplexity, Google AI Mode, and Google AI Overviews, 50 real questions your buyers ask, and record every answer, citation, and omission.
  3. CRISP Score Each answer is scored across Consensus, Reputation, Influence, Source, and Presence, producing a single benchmark for how strongly and accurately your brand appears in AI-generated answers.
  4. Strategy-Wide AI Assessment We rate every area of your strategy for AI optimisation: positioning, website and technical setup, SEO, content, paid media, PR, social and executive profiles, partnerships, listings, and sales enablement. Each area returns its gap and the change that closes it.
  5. Direction & Delivery We sit as the strategy layer across the plan, sequencing the work by commercial impact and briefing whoever executes it, including your in-house team and any SEO, digital, web, or content agency you already retain.
  6. Re-audit & Monitoring Quarterly re-audits track the CRISP score and the answers themselves, so you can see representation improving engine by engine, question by question, and hold every supplier to the same standard.

Who this is for

  • CEOs and boards who have never checked what AI engines say when buyers ask about their category
  • Marketing leaders whose category shortlists are now generated by ChatGPT, Claude, Gemini, Copilot, Perplexity, Google AI Mode, and Google AI Overviews
  • Companies running an SEO or digital agency already, who need one strategy layer governing that work for AI
  • CMOs with a strategy in market who want every area of it assessed and prioritised for AI visibility
  • Companies that have rebranded, merged, or renamed and need AI engines to represent the new identity
  • Established brands with strong media coverage that has not translated into AI-engine presence
  • In-house teams and agencies that need leadership education and capability on AI visibility

What this delivers

Your Whole Strategy, Assessed for AI

The audit reads the plan you are already running and rates every area of it for AI visibility, from your technical setup and SEO through to PR, listings, and sales enablement. You get an AI optimisation plan mapped onto work you have already committed to.

One Strategy Layer Over Every Supplier

We set the AI standard, sequence the work, and brief the specialists who deliver it, including the SEO, digital, web, and content agencies you already retain. Each supplier gets clear specifications and a review cycle, under a single strategy.

You See What the Engines Say

The audit replaces guesswork with evidence: a CRISP score, a question-by-question record of where you appear, and the specific competitor holding your slot in AI-generated shortlists.

Earned Media the Engines Cite

AI engines weight authoritative, independent sources. Our earned media programmes place your story in the publications the engines draw on, so coverage works twice: with readers and with the layer that answers for them.

Accuracy You Can Defend

When AI answers misstate your products, your leadership, or your record, the commercial cost is invisible until you measure it. We correct the record at the source level and keep monitoring it.

What is marketing for AI?

Marketing for AI is the practice of making a company discoverable and accurately represented in answers generated by AI engines such as ChatGPT, Gemini, Claude, Copilot, Perplexity, Google AI Mode, and Google AI Overviews. It combines authoritative structured content, entity consistency, and earned media that AI engines cite. The market also calls this work generative engine optimisation (GEO) and answer engine optimisation (AEO).

How is this different from SEO?

Search optimisation targets ranked links. The Fourth Hemisphere targets the answer itself: what AI engines say, recommend, and cite when asked about your category. It also operates at a different altitude. We take your whole marketing strategy as the input and assess every area of it for AI visibility, then sit as the strategy layer directing the specialists who deliver each part, including your SEO agency.

Do we need to replace our SEO or digital agency?

No. Your existing agencies keep delivering the work they do well. Third Hemisphere sits above them as the strategy layer, setting the AI visibility standard, sequencing priorities, writing the specifications each supplier works to, and reviewing output against the standard. Where you have no supplier for an area the audit flags, we can deliver it or help you appoint someone.

Why does the audit need our marketing strategy?

Because AI representation is produced by everything you already do: your website structure, your content, your earned coverage, your listings, your partnerships, and how consistently your entity data appears across all of them. Reading the strategy lets us rate each of those areas, show which one is holding your score down, and prioritise by commercial impact rather than by channel convenience.

What is the CRISP methodology?

CRISP scores how a brand appears across AI engines on five factors: Consensus (do the engines agree about you), Reputation (do they recommend you, or merely list you), Influence (does anyone but you carry your account of yourself), Source (does your own content hold up as the record), and Presence (do they reach you at all when a buyer describes the need). The audit produces a benchmark score out of 100 and a question-level record behind it. CRISP replaced PACT, a four-dimension model, in September 2026.

What does The Fourth Hemisphere Audit involve?

We ask the seven engines 50 real questions your buyers ask, record every answer and citation, and score the results with the CRISP methodology. You receive the score, the evidence behind it, and a prioritised plan for improving the answers.

What does it cost?

The audit is a fixed-fee engagement, and programmes are scoped from the audit's findings. Book a discovery call and we will confirm pricing for your category and markets.

How long before AI-engine answers change?

Engines refresh their retrieval sources continuously but reweight authority over months, so programmes run 6 to 12 months with quarterly re-audits. Some corrections, such as fixing inaccurate entity data, can move answers faster than building presence from zero.

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