This is a simple modification of a script by Cristo, that pre-sets the radio-button (bubble) selections to a logical default. I just added the appropriate URL match to make it only run on Webs Image Filter HITs. I prefer not to need to enable/disable different scripts for different HITs when they aren't specific enough. Note: the intent is to allow you to focus more on looking at the images rather than on doing as much unnecessary tabbing or clicking.
The requester changed their account's display name from 'Webs Image Filter' to 'Vistaprint Digital Image Filter' in Nov 2015.
See also: my MTG thread post
For many more MTurk-related userscripts, see the Turking Scripts set