Although the behavior described in the preceding paragraph conforms to the idea that newsletter advisers naively extrapolate trends, the situation is more complex. Advisers responded differenfly to that same 1 percent increase in the S&P 500 had it occurred during the preceding twenty-six weeks, as opposed to the preceding four weeks. Now the chickens register a 0.4 percent increase, which is even larger than the 0.3 percent increase in bulls. Clarke and Statman refer to this phenomenon as nervous bullishness. There is heuristic diversity. Unlike the response to a four-week increase, where the migration in sentiment is from bears to bulls, the response to a twenty-six increase is a migration from bears to an even combination of bulls and chickens.