Surprised at vs. Surprised by vs. Surprised to (Surprised + Infinitive)
How to use idioms with the participle "surprised" correctlyThis is an entry on my list of Common Errors in English Usage. Visit the main page for direct links to additional entries.
The past participle surprised can be used with infinitives (verb forms beginning with to):
surprised to discover that he had left
One can be surprised by many things:
surprised by the attention she received
surprised by the sudden change in direction
In addition, one can be surprised at a person (or a person’s behavior, attitude, etc.) for not meeting your expectations. Usually this connotes an attitude of disappointment:
surprised at your disrespectful attitude
surprised at his sudden reluctance to help
Note that in the last two examples above, surprised by would also be acceptable, but it would not convey the connotation of disappointment as clearly; it would convey only the fact of the surprise.
Related Resources
Common Errors in English Usage: Errors in diction and idiom commonly made by native speakers of English
List of Common Errors in English Usage (PDF): Printable version of the complete list
Common Grammar Errors: A list of common errors in grammar (topics like subject-verb agreement and parallelism) as distinct from usage
List of Common Errors in English Usage: PDF version
© 2006, 2008, and 2019 C. Brantley Collins, Jr.