Here's how you can enable or disable the parallax effect (perspective zoom) in iOS 7.1. Turning it off might help prevent motion sickness while using your iOS 7.1 device.
1. Go to Settings.
2. Go to Wallpapers & Brightness.
3. Tap on your wallpaper.
4. Tap the "Perspective Zoom" button at the bottom of your wallpaper.
5. Setting Perspective Zoom to on will give you the parallax effect on your lock screen and home screen.
6. Turning it off will remove the parallax effect on both screens.
Additional resources for iOS