Affect, effect, influence, and impact can be confusing because they often overlap in meaning. They all often translate as “ vaikuttaa” or “vaikutus” in Finnish but they have subtle differences in use in English. These words can be verbs or nouns all refering to something causing a change, but the strength and context of the change vary. This is tricky but lets look at how to handle them correctly.

Verb Use: No preposition added

• Influence: Used for a neutral or positive change, often softer and involving people. Example: We want to influence decision making.
• Affect: Typically refers to a negative or neutral change. Would not be used in a positive situation. Example: The strike affected public transport.
• Impact: Implies a strong effect. Sometimes considered too strong to be used as a verb (especially in UK English). Example: The proposals will impact the paper industry.
• Effect: This word as a verb does not mean “vaikuttaa” – it means implement or carry out. Example: It took a year to effect the reforms.

Noun Use: Influence, Impact, and Effect + preposition “on”

• Influence: Can be positive, neutral, or negative. Example: The manager had a great influence on the process.
• Effect: Also positive, neutral or negative, referring to the result of an action. Example: The weather will have an effect on festival ticket sales.
• Impact: Stronger than "effect," often referring to a significant change. Example: The motorway had a notable impact on local residents.
• There is no noun from the verb “effect” meaning implementation: Instead we would talk about the implementation or execution. Example: The implementation of the new law was complex.

Now try this quiz to test your knowledge: