If John's wage increases from $10 to $12 per hour,his opportunity cost of leisure has decreased or increased,depending on what he does with an hour of leisure.

Substitution Effect

Changes in what consumers purchase, brought about by alterations in the relative costs of goods, persuading consumers to opt for alternatives over their usual choices.

Income Effect

The correlation between income changes in an economy or for individuals and their effect on the quantity of goods and services demanded.