Uncanny valley

Uncanny valley

Many people, whilst not afraid or phobic, find waxworks and Victorian dolls make them uneasy or unsettled.  The uncanny nature of mannequins and puppets is used to great effect in tales of ventriloquists’ dummies that come to life.  Given the long history of such stories it might be a surprise to find out that research into this is comparatively recent.

It was whilst working on robotics in 1970, and specifically the way the humans interact with robots, that professor Masahiro Mori developed the idea of the “uncanny valley”.  This states that as robots and figures become more and more realistic looking so our comfort with them increases, but with one important exception.  At a critical point the increasing realism suddenly provokes disquiet and revulsion – the “uncanny valley” shown in the graph – just before full realism and comfort are attained.




To take an example from Mori’s field of research a robot that has a human shape but clearly isn’t human (such as C3-PO in Star Wars) is much more easily accepted than something which looks almost human but isn’t – such as a doll, a waxwork, or even a CGI effect in a film.  When the film “The Polar Express” was released several reviewers described it as eerie and disconcerting.  The film famously used computer animated characters modelled on Tom Hanks, and the rendering of their faces left them looking to many people as “dead-eyed”, and the Polar Express more resembling “a zombie train

The exact psychological reasons for the uncanny valley reaction are still subject to debate, but like many other fears it seems to be rooted in human evolution.  At its most basic level one theory is that a human appearance that isn’t matched by natural human movement may be an indicator of disease or a poor choice of mate.  Akin to this is the idea that the mismatch between appearance and movement triggers an inbuilt warning about lures and predation.

Whatever the original evolutionary advantage, our brains now respond negatively to conflicting perceptual cues.  For instance if a robotic figure is seen to move robotically then the observer will experience no discomfort.  If a human looking figure were seen to move in the same way it would be experienced as eerie or disconcerting.  The seat of this appears to be in the brain’s visual cortex that processes bodily movement and is linked to mirror neurons in the motor cortex.  When the appearance and the movement don’t match as we expect them to then our brain flags up the discrepancy and the possible danger.

Click here to find out more about other fears based in human evolution.