Sentence:  Psychical blindness is a condition in which there is a total absence of visual memory-images , a condition in which , for example , one is unable to remember something just <WSD>seen</WSD> or to conjure up a memory-picture of the visible appearance of a well-known friend in his absence . 
Meaning of the word marked with <WSD> tags:  perceive by sight or have the power to perceive by sight