1) Mention 2) Observation 3) Perception 4) Perception after the fact 5) Reference 6) Reference to things past 
• (n.) The act, or the faculty, of looking back on things past.
(from the article `mind, philosophy of`) ...some states of mind cannot be introspected, but it does not follow that none can be introspected; they might still be private for all that. Ryle, ...
The act or process of surveying and reviewing the past. ... Origin: retro-+ L. Specto, pp. Spectatus, to look at ... (05 Mar 2000) ... 
Re`tro·spec'tion noun The act, or the faculty, of looking back on things past. 
Type: Term Pronunciation: ret′rō-spek′shŭn Definitions: 1. The act or process of surveying and reviewing the past.
Act of talking about events that took place at a point in the past.
[n] - reference to things past 2. [n] - memory for experiences that are past
noun memory for experiences that are past; `some psychologists tried to contrast retrospection and introspection`