When a new driver gets into a situation where she begins to tense up (this can happen when you experience an increase in traffic, or when you are getting onto a crowded freeway or merging into a crowded access or feeder road), she often will hold the steering wheel tighter.  The tighter grip actually may cause the vehicle to drift out of the center of the lane.  It’s easier to maintain the center of your intended path with a light grip on the steering wheel while you are targeting well ahead.

A firm grip is usually only needed in an emergency situation such as a blowout where a firm grip is needed because the directional forces acting on the vehicle are strongly pulling the vehicle away from the intended path.