The paintings depict isolated figures enclosed in spaces that are undefined , overwhelmingly claustrophobic , reductive and eerie . Coming early in Bacon 's career , they are uneven in quality , but show a clear progression especially in how they utilise and present ideas he was still clearly developing and coming to terms with . Head I ( actually begun in the winter of 1948 ) and Head II show formless pieces of flesh that broadly resemble human heads ; they have half @-@ open eyes and a pharynx , though it is positioned much higher than would be expected in a human . Heads III , IV and V show fully formed busts recognisable as men , and are characterised by a haunted atmosphere . These two broad ideas coalesce in Head VI , which is as physiologically tortured as the first two paintings , and as spectral as the middle three . In Head VI the figure has developed and is now shown wearing vestments , the first indication in Bacon 's work of the influence of Velázquez , while the focus has become the open mouth and the study of the human scream .