It has often been noted that some aspects of dyslexia and autism are just different points on the same spectrum. This includes problems reading facial emotions and has even been suggested as an early diagnostic tool for autistic children.
A recent study [PDF of full text] in the Journal of Vision has been comparing how we recognise faces and how we read words. Myomancy has covered the question of how we read (The Psychology of Reading) before and the basic debate is do we recognise the word as a whole unit or do we identify the individual letters and work out what they spell? The same same question applies to the face; do we employ a holistic approach or do we identify individual features. The study examines the impact of crowding, e.g. how close the letters / features are together and it demonstrated that facial and word recognition skill worked in very similar ways. This may give us a reason why poor reading skills often go hand in hand with poor social skills.