You've been dreaming about that summer break on the sun lounger, book in one hand and drink in the other, for months. Now the dash to the airport gate, train station or hours-long drive is all that stands in your way.

But what does the book you've just shoved in your suitcase say about you?

"It's definitely not a random choice," says Edgar Dubourg, a cognitive scientist at the École Normale Supérieure in Paris. "Your reading list is basically a map of your personality.

"When you pick a thriller or romance or horror or science fiction you're not escaping your psychology, in a way, you're really feeling very intuitive and very old parts of your brain.

"Fiction isn't inventing new emotions in you. It's pressing on those pre-existing motivations like instincts."

Studies have shown that our book choices can subconsciously reveal important parts of our personality - including what gives us pleasure and what makes us feel emotion.

Research by Dr Valerie van Mulukom, a senior lecturer in psychology at Oxford Brookes University, suggests that our inner anxieties (or what she calls existential insecurities) determine which book we pick from the shelf.

During her study, she used how often someone might engage with a certain genre to match it up with one of the following four clusters:

But what do they mean? And how do they match up with our own anxieties?