Completion Bias
Completion Bias

Definition
Completion bias is the tendency of people to feel compelled to complete a task once they have started it. We are more motivated to tackle tasks that we are confident that we can complete because we get a certain amount of satisfaction from finishing them.
A common strategy used in conversion rate optimisation which utilises completion bias is to insert the first 2 or 3 fields of a sign-up form onto a landing page. When a user clicks on the landing page CTA their data is then automatically transferred to the main registration form. This has the advantage that the registration process begins earlier in the user journey, and this encourages customers to make a small, but significant commitment, to continuing and finishing registration.
Resources:
Conversion marketing – Glossary of Conversion Marketing.
Over 300 solutions reviewed – Digital Marketing toolbox.