In the United States during the late 1980s, most Democrats wrongly believed that inflation had risen under Republican president Ronald Reagan. In 2010, most Republicans wrongly believed that taxes had increased under Democratic president Barack Obama. These incorrect beliefs best illustrate the impact of:

in-group bias

Explanation:

In-group bias, also known as in-group favoritism can be described as the tendency of people to favor those that belong to the same group with them, which can be reflected in the way they evaluate issues, and even when allocating resources.

In the scenario cited in the question above, the impact of in-group bias is illustrated, as Democrats in their evaluation of the regime of a government, tend to favor the president that belongs to their party, while, the Republicans favor their own party members, as each group wrongly evaluate each other.

explanation:

with the profits from the european sales, merchants purchased europe's manufactured  goods, including tools and weapons. then the merchants shipped those manufactured  goods, along with the  american  sugar and rum, to west africa where they were bartered for  slaves.