The article published by Pie in 2005 presents a model for the interaction between predators and prey. More specifically, Pie has created a model designed to show how a predator makes selection between prey that is acceptable to attack and that which is not, as well as separating the prey from the background environment. The model is theoretical, and provides a rough basis that can be used to interpret field findings.

The model proposed by Pie (2005) shows three parabolic curves with overlapping edges. The amount these overlap are determined by the predators sense organs and the natural overlap between safe prey and background noise or unsafe prey. Using this model, arbitrary cut-off points are designated by the animal which allow it to select prey. These cutoff points naturally include prey that should not be attacked, referred to as acceptance error, and prey that is allowed to escape when it could safely be attacked, known as rejection error. Those animals that fall into the background noise are well-camouflaged, while those safe prey that appear to fall into the dangerous category either mimic dangerous prey or produce startle displays.

The use of this model is that it provides a basic understanding of how the predator selects its prey. It relates to the class on signal evolution only slightly, with more of an emphasis on signal information. The predator has to use this model to decide if the thing it is viewing is acceptable prey, or if it is actually a piece of bark or an animal that releases some form of toxin. In order to do this, it must interpret the information it receives from its prey and make a decision, which leaves the prey a rejection error margin which it can exploit to avoid attack.

Pie, R.M. (2005). Signal evolution in prey recognition systems. Behavioral Processes, 68(1): 47-50.