The Fourth Hemisphere: Marketing for AI

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

ChatGPT, Claude, Gemini, Copilot, and Perplexity 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 five major 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 PACT 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 five major 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, and Perplexity score your brand with our PACT methodology across Presence, Authority, Consensus, and Truth, 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
PACT scoring across Presence, Authority, Consensus, and Truth
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

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.
Engine Audit We ask the five major AI engines, ChatGPT, Claude, Gemini, Copilot, and Perplexity, 50 real questions your buyers ask, and record every answer, citation, and omission.
PACT Score Each answer is scored across Presence, Authority, Consensus, and Truth, producing a single benchmark for how strongly and accurately your brand appears in AI-generated answers.
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.
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.
Re-audit & Monitoring Quarterly re-audits track the PACT 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.

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, and Perplexity. It combines authoritative structured content, entity consistency, and earned media that AI engines cite.

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 PACT methodology?

PACT scores how a brand appears across AI engines on four dimensions: Presence (do you appear at all), Authority (are you positioned as credible), Consensus (do the engines agree about you), and Truth (is what they say accurate). The audit produces a benchmark score and a question-level record behind it.

What does The Fourth Hemisphere Audit involve?

We ask the five major AI engines 50 real questions your buyers ask, record every answer and citation, and score the results with the PACT 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.