Planning. Short-term memory. Attention. At first glance, these three frontal lobe functions can seem like diverse activities that just happen to be packed into the same brain region. But on closer inspection it turns out that they are facets of the same basic phenomenon of 'restraint'. Planning restrains our brains from wandering from a chosen path of activity. Short-term memory retrains sensory cortex from moving on to different imagery. Attention constrains the kind of sensory data admitted to sensory cortex.