Fig. 6. Results of visual impairment experiment. Each dot represents the angular
difference between an individual turtle's mean heading on Day 2
versus Day 1. Loggerheads in all three treatment groups maintained
similar headings on Day 1 and Day 2. (A) No treatment; mean angle=356°,
r=0.61, P<0.01 V-test, 95% confidence interval
±51°; (B) Goggles with no lenses; mean angle=9°, r=0.58,
P<0.01 V-test, 95% confidence interval ±51°; (C)
Goggles containing frosted lenses; mean angle=335°, r=0.60,
P<0.01 V-test, 95% confidence interval ±48°. The
expected direction in all cases was 0°. See text for statistical
comparison of distributions.