The uncanny valley is a concept in aesthetic design that is as follows; As an object is given more and more human features, people develop an affinity to that character (consider Pixar's Cars or the object characters in Banjo Kazooie). As the characters become even more human they are stylized humanoid characters and people connect with them even more (Mario, Megaman etc). However before perfect photo-realism graphics are achieved there is a significant drop and people are repelled by the likeness. As the theory goes, humans are extremely good at identifying faces and if there is a slight difference, it stands out and destroys the entire illusion. This concept is illustrated perfectly in Figure 1. It should also be noted that this is only amplified by movement in animation and video games. When considering an aesthetic, a developing studio should think hard about which side of the uncanny valley they want their game to sit on.
LA Noire used MotionScan technology to scan in the faces of real actors to play the parts of the characters in the game. During cut scenes this resulted in amazingly realistic graphics for 2011. However when focused on during the interrogation scenes and particularly when combined with stiff unnatural body movement, the game lands perfectly in the uncanny valley. These animations pull the player completely from the immersive experience and can even creep them out at times.
The facial animations in this game were advanced for the time, but the character models look clunky and unnatural in certain scenes. This results in awkward scenes that look forced or unnatural. Rather than looking as though the characters are kissing, it seems as if they simply smashing thier faces together, and a scene that's supposed to be serious in tone comes off as awkward parody.