Inflation has reached its lowest point in 2 1/2 years. The unemployment rate has stayed below 4% for the longest stretch since the 1960s. And the U.S. economy has repeatedly defied predictions of a coming recession. Yet according to a raft of polls and surveys, most Americans hold a glum view of the economy. The disparity has led to befuddlement, exasperation and curiosity on social media and in opinion columns. Many factors lie behind the disconnect, but economists increasingly point to one in particular: The lingering financial and psychological effects of the worst bout of inflation in four decades.