There are a few options here, and it's all dependent on making sure you're using a synaptics touch device.

In trusty 14.04 there is a natural scrolling feature available if the system detects you are on a synaptics device:

You may need to blacklist the i2c module

echo "blacklist i2c_hid" | sudo tee -a /etc/modprobe.d/blacklist.conf

The final option, if all else fails, is by adding a PPA to add the Natural Scrolling application:

Add ‘ppa:zedtux/naturalscrolling‘ to your Software Sources, update, then install the ‘naturalscrolling’ package from the Ubuntu Software Centre.