Mock viva practice: how to rehearse your thesis defence

What is a mock viva?

A mock viva is a practice run of the PhD viva voce examination. It simulates the experience of being questioned on your thesis before the real examination takes place. The format varies — it might be a formal session arranged by your department, an informal conversation with your supervisor, or an independent practice session.

What all mock vivas share is the attempt to reproduce the core challenge of the real viva: defending your research in a spoken conversation with someone who has read your work and is asking critical questions about it.

Why spoken practice matters

Most PhD viva preparation is reading-based — going back through the thesis, reviewing notes, preparing answers in your head. This is necessary, but it is not sufficient. The viva is a spoken examination, and the distance between knowing something and being able to explain it clearly under questioning is larger than most candidates expect.

When you speak your answers out loud, several things happen:

• You discover where your reasoning is not yet crisp. Ideas that feel clear in your head often become vague when you try to articulate them precisely.
• You build vocabulary for explaining your work. The first few times you explain your methodology are often clumsy. The tenth time is much better.
• You practise responding to follow-up questions, which requires the kind of in-the-moment flexibility that reading alone cannot develop.
• You familiarise yourself with the experience of being questioned — reducing the novelty of the format on the day itself.

How to prepare for a mock viva

Before a mock viva session — whether formal or informal — a few things are worth preparing:

• Know your thesis. Re-read it before the session. Know where your key arguments are, where your methodology is explained, what your findings are, and what you claim to contribute.
• Prepare your contribution statement. Be able to state precisely what your thesis adds to the field — clearly and without hedging. This often comes up first.
• Know your limitations. Be ready to acknowledge them precisely and explain their scope. This is not a weakness — it is a sign of intellectual honesty.
• Identify the decisions you'll be asked to justify. Every significant methodological or analytical choice is a potential question. Think through the reasoning for each one.

How to use feedback from a mock viva

Feedback from a practice session is most useful when it is specific and actionable. After a session, it is worth asking:

• Which answers were vague or unclear? What would a more precise version look like?
• Where did follow-up questions catch me out? What do I need to think through more carefully?
• Were there areas I was stronger than I expected? That confidence is real — trust it.
• What would I want to practise again before the real viva?

Multiple practice sessions — even short ones — are more useful than a single long session. Each run gives you new information about where your preparation needs work.

How Defensia provides additional private rehearsal

Formal mock vivas are excellent preparation, but they are difficult to arrange more than once or twice. Defensia is designed to give you supplementary spoken practice time — private, available on demand, and grounded in your specific thesis.

When you upload your thesis, Defensia indexes your work. The AI examiner draws on that index to ask questions about your specific methodology, your specific findings, and your specific arguments. You answer out loud, the examiner responds with follow-up questions, and after the session you receive structured feedback across five categories.

This gives you the kind of repeated spoken practice that is difficult to arrange otherwise — between formal sessions, in the evenings, in the final days before the viva.

Defensia is not a replacement for a formal mock with your supervisor or examiners. It is designed to complement those sessions with additional rehearsal time that is otherwise hard to find.