Hemi-Neglect is a very interesting phenomenon, in which an affected person neglect one half of things. It is strange, and you can not imagine how it is. See photo below.

Hemi-Neglect; a half side of a clock is drown, but the other half is missing.

Etiology: It is caused by a lesion of temporo-parietal lobe, which must be non-dominant side.(*)

This also happens to your meal. When the patient eats his or her meal, he does NOT recognize a half of the dish, that is why the half will be left over...

(*)Dominant side causes Gerstmann syndrome; which also has an interesting feature such as Left-Right disorientation and finger agnosia, which means you can not tell Left or Right and you can not tell which finger it is eg. index finger, respectively.