Why do we tend to pay attention to one thing at a time in our visual field?

Mark the four statements that are true. 1. the democrats blamed the republicans for the stock market crash of 1929. 2. the democrats won the presidency in the 1990's but lost control of the congress. 3. the democratic party is the oldest political party in the united states. 4. the anti-federalists were one of the first two american political parties; they wanted a strong central government. 5. the "era of good feelings" was a period from 1816-1824 where there was only one political party: the democrat-republicans.