Figure 2. Relationship between locomotor activity levels of A. azarai monkeys free-ranging in their natural habitat and luminance levels.
Intermediate light intensities positively mask (increase) locomotor activity in A. azarai. Each point represents the average normalized activity (± SE) of 9 animals for the range of luminances between one log-unit below and the luminance indicated in the x-axis (for instance, the point corresponding to 10−2 lux includes the average activity recorded under luminances >10−3 and ≤10−2 lux). Luminances corresponding approximately to full-moonlit nights, as well dawn and dusk are indicated. The curve represents a 3rd degree equation best fitted to the points that generated each average shown.