@article {308904,
	title = {Symbol addition by monkeys provides evidence for normalized quantity coding.},
	journal = {Proc Natl Acad Sci U S A},
	volume = {111},
	year = {2014},
	note = {http://www.pnas.org/content/early/2014/04/17/1404208111},
	month = {2014 May 6},
	pages = {6822-7},
	abstract = {<p>Weber{\textquoteright}s law can be explained either by a compressive scaling of sensory response with stimulus magnitude or by a proportional scaling of response variability. These two mechanisms can be distinguished by asking how quantities are added or subtracted. We trained Rhesus monkeys to associate 26 distinct symbols with 0-25 drops of reward, and then tested how they combine, or add, symbolically represented reward magnitude. We found that they could combine symbolically represented magnitudes, and they transferred this ability to a novel symbol set, indicating that they were performing a calculation, not just memorizing the value of each combination. The way they combined pairs of symbols indicated neither a linear nor a compressed scale, but rather a dynamically shifting, relative scaling.</p>},
	keywords = {Animals, Behavior, Animal, Choice Behavior, Learning, Macaca mulatta, Male, Mathematical Concepts, Models, Neurological, Models, Psychological, Reward},
	issn = {1091-6490},
	doi = {10.1073/pnas.1404208111},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/24753600},
	author = {Livingstone, Margaret S and Pettine, Warren W and Srihasam, Krishna and Moore, Brandon and Morocz, Istvan A and Lee, Daeyeol}
}
