egl-10 and eat-16 have opposite effects on the frequency of spontaneous reversals. N2 is the wild-type control, egl-10 is egl-10(md176) and eat-16 is eat-16(ad702). For each genetic background, ≥50 animals were tested in at least three independent assays. Numbers of spontaneous inversions per minute are represented. Each bar represents the mean ± SEM. *Difference from N2, P < 0.01; **difference from egl-10(md176), P < 0.01.