realize and notice

Many students of English have trouble with these two verbs, using one where the other would be more appropriate. While they are similar in meaning, they are not identical, as we can see in the definitions and examples below, adapted from the Longman Dictionary of Contemporary English, 3rd edition.

notice: to see, hear, or feel something
• He spilled the tea, but Mrs. Whitley did not notice.
• You may notice a numb feeling in your fingers.
• He was too tired even to notice how tired and hungry he was.
• Did you notice him leaving the party early?

realize 1: to know and understand the importance of something

• Do you realize that you are an hour late?
• I realize how much she means to you.
• None of us realized the danger we were in.

realize 2: to start to know something that you had not noticed before

• I suddenly realized that he was crying.
• Later, we realized that we had met before in Paris.
• I realized then how hungry I was.
• Tim didn't realize his mistake until the next day.

The definitions of realize include the word "know", while the definition of notice includes "see,hear or feel". In other words, realizing is a cognitive event, something which involves thinking about a situation. Noticing is more of a physical event in which something comes to our attention through our senses. It is possible to notice something without realizing that it is important.

Pay attention to the contrast in these two sentences:

• Did you notice what time it was when you came in? (That is, did you happen to see the clock?)

• Did you realize what time it was when you came in? (That is, did you understand that you were late?)