In psychology, picture thinking is often confused with dyslexia, and it is true that people who 'think in pictures' often have difficulty with learning to read, but not all picture thinkers suffer from the normal symptoms associated with dyslexia. Some autistic's think in pictures.
Traits that most picture thinkers do share are:
Thinking with the meaning of language in terms of multidimensional scenarios of the ideas and concepts, as opposed to the sound of language.
Natural ability to 'quick read' whole sentences instead of word for word, but when asked to read out loud what they have read they often use other words than what is actually written.
Ability to remember exactly the location and relative position of objects they have placed somewhere.