FIGURE 4.

Contrast variation but not full field stimulation have wavelength-dependent effects on swimming parameters. (A) Schematic of the modified paradigm used. Briefly, the animal is presented with a split field stimulus as in the figures above, but now the contrast between the two sides decreases if the fish turns toward the lighter side (higher irradiance) and increases if the turn is toward the darker side (lower irradiance). (B) Contrast of each stimulus (UV, blue and red, colored as before) over time, averaged over two trials per experiment and 14 TLAB fish (the lines are mean ± SEM). The units are the logarithm of the total cone excitation difference between the two sides. (C) Modulation of (i) bout frequency, (ii) duration, (iii) peak speed, (iv) turn angle, (v) preference index, and (vi) number of bouts by stimulus contrast (points are averages across 14 animals ± SEM). (D–G) Dependency of bout displacement (D), speed (E), latency (F), and duration (G) on full field stimulation (points are mean ± SEM, N = 23, stars represent a p-value < 0.05 on a paired bootstrap test against the first power level).