Fig 3. Values of sensitivity to food ratio and bias (a and log c, respectively, in Equation 1) prior to each successive food plus magazine light or magazine-light-only presentation across the seven components as the proportion of magazine lights to total events was increased.

Food (F) and magazine light (ML) refer to food plus magazine light and magazine-light-only presentations, respectively: Thus, in Condition 2, for example, we arranged 10 food deliveries and two magazine-light deliveries per component (10 F + 2 ML). The data used were numbers of responses between food presentations averaged across the 6 pigeons in Conditions 1 to 5. The lower-right graph shows mean sensitivity and bias values across Conditions 1 to 5, and mean values for each condition, for comparison purposes.