Normal selling pressure

According to the AmericanBulls.com website, sometimes when a stock decreases it can be either normal selling pressure or the start of a downward trend. The trick is determining which is which. From what I've seen, when a stock decreases on high volume, it's usually a trend. Low volume increases/decreases are usually short lived during periods of volatility. Consecutive days of low volume movements are usually a trend when the movements are in the same direction of the 20 day SMA.

Picks at end of day 9/5/2007:
ACCL, ACCELRYS INC (Google Yahoo Earnings Chart)
BBG, BILL BARRETT CORP (Google Yahoo Earnings Chart)
CESI, CATALYTICA ENERGY (Google Yahoo Earnings Chart)
GMXR, GMX RESOURCES INC (Google Yahoo Earnings Chart)
IHS, IHS INC (Google Yahoo Earnings Chart)
NMHC, NATL MED HEALTH C (Google Yahoo Earnings Chart)
PLAB, PHOTRONICS INC (Google Yahoo Earnings Chart)
RCKY, ROCKY BRANDS INC (Google Yahoo Earnings Chart)
TIV, TRI-VALLEY CORP (Google Yahoo Earnings Chart)

Of these ACCL and GMXR are particularly interesting.