Figure 3.

Relative preferences of chicks to colours on the (a) orange to blue and (b) red to green axes for newly hatched (solid line) and 9-day-old (dotted line) birds. Newly hatched chicks (experiment 1) are substantially more sensitive to chromatic contrast (or saturation) than the older subjects (experiment 2). Data plotted are for the total number of pecks in experiment 1 and the mean number of pecks per pair of chicks for experiment 2. The responses to grey were not measurable in experiment 1. Further details and statistics are given in the text.