|Some computers have the option to press a key during BIOS enumeration such as F1, F8, etc. to choose the boot device.|
For example, if I press F8 key on my Asus M/B computer, I get to the screen where I am asked to choose the boot device, whereas F8 key is normally supposed to present the Windows boot options, such as Safe Mode, Command Prompt, etc..
In some Acer notebooks, a BIOS option should be enabled first before you can use that option, such as disk-to-disk recovery or D2D Recovery, etc.
Therefore, I suggest you to look into the Sony Vaio manual or Sony support forums on the web.