The Sunk Cost Bias: Why a Longer Onboarding Can Convert Better Than a One-Click Signup

Spending ten minutes setting up an account, then wanting to quit, triggers a discomfort out of proportion with the time actually lost. This reflex has a name: the sunk cost fallacy. It pushes people to keep going with a commitment because of what they've already invested — time, money, effort — rather than what continuing actually delivers. On a landing page, this bias isn't just a psychology curiosity: it explains why a longer onboarding flow, counterintuitively, sometimes retains better than a one-click signup.

What the research says about sunk cost

The phenomenon was formalized by Hal Arkes and Catherine Blumer in a foundational study published in 1985 in Organizational Behavior and Human Decision Processes. Their experiments show that participants who had already invested money or time in an option kept favoring it even when an objectively better alternative appeared, simply out of a refusal to "waste" what had already been committed (study on Google Scholar). A more recent study by Raghuram Iyengar, Young-Hoon Park and Qi Yu, published in 2022 in the Journal of Marketing Research, applies the mechanism to paid subscription programs: it shows that customers who paid an upfront membership fee increase their purchases to justify that spend, and that two-thirds of this effect is not explained by real economic benefit but by this psychological justification reflex (study on Google Scholar).

Three places where this bias acts in your funnel

1. The multi-step form

A visitor who has already answered three questions in a multi-step form hesitates more to close the tab than a visitor facing a single, still-blank block: abandoning would mean losing the effort already put in. This is one of the mechanisms that make a multi-step form outperform one long single-block form, alongside the Zeigarnik effect (the tension of an unfinished task) that we cover in our article on the Zeigarnik effect. A progress bar makes that investment visible step by step, reinforcing the effect with every screen completed.

2. The free trial with an initial setup

A free trial that requires connecting data, inviting colleagues, or customizing a dashboard before it delivers value deliberately creates an early investment cost. Once that setup is done, abandoning costs more psychologically than continuing, even against a cheaper competing offer. This is a different mechanism from the endowment effect (which plays on a sense of ownership): here, it's not what the user owns that matters, but what they spent to get it. The two combine well in SaaS onboarding, a topic we dig into in our comparison of free trial vs. freemium.

3. The upfront-paid subscription

The Iyengar et al. study confirms it: an upfront financial commitment (an annual subscription rather than monthly, a bundle rather than a one-off purchase) pushes people to use the service more to "get their money's worth" out of the spend already made. That's an additional argument, alongside price anchoring, for foregrounding an annual price on a sales page — a trade-off we detail in monthly vs. annual pricing.

Where persuasion stops and dark patterns begin

Exploiting this bias has a clear ethical limit. Artificially lengthening a flow to trap a visitor — hiding a cancel button, adding steps with no real value just to manufacture a sense of investment — crosses into dark pattern territory, with a real risk of brand damage and, in Europe, legal exposure under GDPR and the Digital Services Act. The difference lies in the real value of each step: onboarding that genuinely personalizes the product serves the user as much as conversion; onboarding that exists only to retain serves conversion alone, and it shows quickly.

Designing an onboarding that invests without trapping

• Only ask for information the product actually uses to personalize the experience — every unnecessary field erodes trust without building commitment.
• Show progress at every step, with a progress bar or a step counter, to make the investment visible without forcing it.
• Deliver a concrete first result before asking for payment — a filled-in dashboard, a personalized recommendation — so the initial investment has a tangible payoff.
• Always leave an exit path as simple as the entry path: one-click cancellation builds trust and, paradoxically, reduces the anxiety that keeps some visitors from ever committing in the first place.

How to check the effect on your own funnel

The sunk cost bias isn't something you assume, it's something you measure. Before restructuring a form or an onboarding flow on this intuition alone, compare the drop-off rate at each step rather than the overall abandonment rate: a funnel where drop-off falls sharply after the second or third step, compared to abandonment before the very first answer, is a signal consistent with the effect described by Arkes and Blumer. A behavioral analysis tool or simple per-step event tracking in your analytics is enough to make the point objective, in line with what we cover on measuring form abandonment.

An A/B test remains the most rigorous way to settle the question: pit a version that asks for a personalization detail at the very first step against a version that defers it to the end of the flow, then compare not just the final conversion rate but also 30-day retention across each variant's users. The sunk cost bias predicts a gap that widens after conversion, not just at signup — exactly what the Iyengar, Park and Yu study on upfront-paid subscriptions suggests. Our A/B testing guide covers how to size that kind of test correctly.

The case of LanderKit templates

The SaaS Waitlist template (see the demo) is built for exactly this case: a waitlist with an enriched form, a queue position, and a share button that create an initial investment even before the product launches. The Coach & Consultant template (demo) applies the same principle to a discovery call: the more a booking flow asks a prospect to detail their needs upfront, the more engaged they show up on the day. In both cases, the mechanism stays in service of better qualification, never a trap on the way out.