Incorrect spelling, explanation: over time, the English language standardized shown as the correct past participle of show. Language rules are often influenced by historical development, and forms like showed never became part of acceptable usage. Adding -ed to shown would result in showned, which incorrectly tries to mark the past tense twice. Since shown already indicates that the action has occurred, adding another -ed serves no purpose and breaks grammatical conventions.

Correct spelling, explanation: the -n ending in the past participle of show (shown) follows a pattern seen in many strong verbs inherited from Proto-Germanic, where past participles often took on a distinct suffix. These -n endings became standardized in Middle and Modern English as markers for past participles in certain irregular verbs. The form showned is not correct in English because it does not follow the established grammatical rules for the verb show or other similar irregular verbs.

Definition of shown:
Verb (past participle), to make it possible for something to be seen:
The teacher has shown us how to solve the problem step by step.
The results have shown that the new strategy is effective.

Collocations with shown:
Some of the most commonly used collocations include:
1. To have shown appreciation: to express gratitude or recognition.
She has shown appreciation for all the help her team provided.
2. To have shown a preference: to express or indicate a liking for something.
He has shown a preference for working in the mornings rather than afternoons.
3. To have shown concern: to demonstrate care or worry about something.
The community has shown concern over the rising pollution levels.
4. To have shown leadership: to demonstrate qualities of a leader.
The manager has shown leadership by guiding the team through difficult times.