Kemp Simon
University of Canterbury, Department of Psychology, Private Bag 4800, Christchurch, New Zealand.
Behav Processes. 2005 May 31;69(2):131-2; author reply 159-63. doi: 10.1016/j.beproc.2005.02.011.
Sometimes, an organism can use a simple optimisation heuristic. It does not need to calculate optimality functions, but can instead proceed by evaluating gradients in its environment and following a path that leads towards a local maximum or minimum.