How to turn off "show preview" on imessages

Hello. I have an iphone 5 with verizon. my software is up to date with ios 6.1.4. I would like to know how to prevent my text messages and immesages from showing on the screen of my phone.

i went to settings, imessaging, and looked for a "show preview" to turn off but i do not have that option in messages. i only have send read receipts, send as sms, sand and receive, mms messaging, group messaging, show subject field, and character count.

can someone please show me how to turn of the imessage and text message preview that pops up on the home screen of my phone. thansk.